A mysterious, spider-like structure lurking on Jupiter's fourth-largest moon, Europa, may finally have a proper explanation nearly 30 years after it was discovered. The arachnid imposter has also been given a demonic new name.

In March 1998, NASA's Galileo spacecraft — which studied Jupiter and its major moons between 1995 and 2003 — made a close flyby of Europa, a frozen ocean moon often considered one of the most likely places for extraterrestrial life to exist in the solar system. During this flyby, the probe mapped out a roughly 13.7-mile-wide (22 kilometers) impact structure, dubbed Manannán Crater, on the moon's icy surface, and found something strange lurking within it.

Hidden inside a deep pit near the crater's center was a sprawling dendritic shape. The researchers initially believed the dark feature was caused by the extreme gravitational force exerted on Europa by Jupiter, which is responsible for carving multiple fracture lines across the water world's surface. Other experts have since proposed that it was created by eruptions from hydrothermal vents on the floor of Europa's subsurface ocean. However, neither of these explanations fully explain this unusual shape.

But in a new study, published Dec. 2 in The Planetary Science Journal, researchers proposed an alternative explanation: that the Jovian spider formed in a similar way to how dark dendritic patterns on Earth, known as "lake stars," typically do. These features form when snow falls on frozen lakes and water seeps up through tiny holes in the ice.

With this in mind, the researchers used a similar technique to partially recreate the Manannán Crater's mysterious shape in the lab. The study team also finally named Europa's arachnid-like asterisk Damhán Alla, meaning "spider" or "wall demon" in Irish. (Manannán is a Celtic god from Irish mythology, which partly inspired the new name.)

"Lake stars are really beautiful, and they are pretty common on snow or slush-covered frozen lakes and ponds," study lead-author Lauren Mc Keown, a planetary scientist at the University of Central Florida, said in a statement. "It is wonderful to think that they may give us a glimpse into processes occurring on Europa and maybe even other icy ocean worlds in our solar system."

However, rather than water rising through tiny holes, as happens when lake stars form on Earth, Damhán Alla was likely birthed by an asteroid impact — which created a small crack in Europa's icy shell that enabled salty water to seep upward and paint the spider-like pattern on the surface. (This asteroid impact likely happened after the Manannán Crater was already formed.)

The researchers also noted similarities between Damhán Alla and the infamous "spiders on Mars," which are dusty deposits on the Martian surface that look like swarming spiders when viewed from above. These fake arachnids, known as araneiform terrain, form when submerged carbon dioxide ice sublimates, or turns directly into a gas. Mc Keown's team has previously recreated these features on Earth too.

The similarities in shape between Damhán Alla and the spiders on Mars are due to how "fluid flows through porous surfaces," Mc Keown said. In theory, similar spider features could also form on other frozen ocean worlds, such as Saturn's moon Enceladus, Jupiter's other moon Ganymede and the dwarf planet Ceres, which resides in the asteroid belt beyond Mars.

Mc Keown is now setting up a new laboratory, which will focus on studying how these various spider-like features may form on different solar system moons. She hopes to be able to provide valuable insight that could help inform NASA's Europa Clipper mission, which launched in October 2024 and will arrive to extensively study Jupiter's watery moon in 2030.

"The significance of our research is really exciting," Mc Keown said. "Surface features like these can tell us a lot about what's happening beneath the ice. If we see more of them with Europa Clipper, they could point to local brine pools below the surface," she added.

And these pools could be a good place to start looking for signs of extraterrestrial life.

Tiny tropical spiders in the Philippines and the Peruvian Amazon build giant, arachnid-like decoys in their webs to scare off predators, new research shows.

The outsize fake spiders are made of silk; plant debris; and dead, disembodied prey. Some decoys look rudimentary, but others accurately imitate the shape of a spider, according to a study published Nov. 6 in the journal Ecology and Evolution.

The builders of these decoy spiders are the orb weavers Cyclosa inca and Cyclosa longicauda, which measure just 0.1 inch (2.5 millimeters) long. Their spiderwebs are classic wheel shapes made of silk, but inside them lie important clues about spider survival strategies in a world filled with predators.

"They don't just decorate their webs — they meticulously arrange detritus, prey carcasses and silk into a structure that's not only larger than their own body, but clearly resembles the silhouette of a bigger, menacing spider," study lead author George Olah, a conservation geneticist at the Australian National University, said in a statement.

Unlike other orb weavers that build silken tubes to hide inside in their webs, the two Cyclosa spiders invest their time, energy and resources into crafting these decoys. This means the fakes are more than a quirky biological observation, study co-author Lawrence Reeves, an assistant professor at the University of Florida's Medical Entomology Laboratory, said in the statement.

"It illustrates a fundamental evolutionary trade-off in the spider world," Reeves said.

Researchers have known about Cyclosa spiders' strange antics for some time, but the new study is the first time the decoy-building behavior has been formally documented and interpreted.

The spiders turn their webs into "theaters of deception" to stave off would-be attackers, Olah said.

The decoys likely intimidate birds, lizards and other natural predators, prompting them to stay away. They may also provide camouflage for the small Cyclosa spiders, which have the same coloration as their creations and can therefore hide among the plant matter and prey remains.

The decoys may be as effective in defending Cyclosa spiders against predators as the retreats other orb weavers build, explaining why the spiders invest their energy into making them, according to the study. When predators approach the webs, Cyclosa spiders concealed within the decoys shake their abdomen to create vibrations in the fake spiders that make them seem alive.

The spiders do this day and night, the researchers wrote in the study. "When further approached, the spider jumped off from the web to the ground," they noted of a handful of observations in the Peruvian Amazon in 2022, adding that arachnids returned to their webs once the perceived threat was gone.

The decoys may also provide safe places for Cyclosa spiders to lay their eggs, Juan Carlos Yatto, a nature guide in Peru's Tambopata National Reserve who worked with the study's authors, said in a video. The spiders move the contents of their webs to new locations by building a single thread, along which they transport their eggs and all the debris and body parts used for their decoy. In this scenario, the disassembled decoy can camouflage the eggs during relocation, Yatto said.

Other benefits of building decoys could be that they attract prey and strengthen spiderwebs against adverse weather, the researchers wrote in the study. Further research is needed to understand these different advantages, Olah said.

Cyclosa spiders and their strangely decorated webs are featured in the documentary series "The Secret Lives of Animals."

Spider quiz: Test your web of knowledge

Researchers have discovered more than 111,000 spiders thriving in what appears to be the world's biggest spiderweb, deep inside a pitch-black cave on the Albanian-Greek border.

The "extraordinary" colony consists of a colossal web in a permanently dark zone of the cavern, according to a study published Oct. 17 in the journal Subterranean Biology. The web stretches 1,140 square feet (106 square meters) along the wall of a narrow, low-ceilinged passage near the entrance of the cave. It is a patchwork of thousands of individual, funnel-shaped webs, the researchers noted.

This is the first evidence of colonial behavior in two common spider species and likely represents the largest spiderweb in the world, said study lead author István Urák, an associate professor of biology at Sapientia Hungarian University of Transylvania in Romania.

"The natural world still holds countless surprises for us," Urák told Live Science in an email. "If I were to attempt to put into words all the emotions that surged through me [when I saw the web], I would highlight admiration, respect, and gratitude. You have to experience it to truly know what it feels like."

The spider megacity is located in Sulfur Cave, a cavern that was hollowed out by sulfuric acid formed from the oxidation of hydrogen sulfide in groundwater. While the researchers revealed tantalizing new information about Sulfur Cave's spider colony, they weren't the first to see the giant web. Cavers with the Czech Speleological Society discovered it in 2022 during an expedition in the Vromoner Canyon. A team of scientists then visited the cave in 2024, plucking specimens from the web that Urák analyzed before going on his own expedition to Sulfur Cave.

This analysis revealed that two spider species live in the colony: Tegenaria domestica, known as the barn funnel weaver or domestic house spider, and Prinerigone vagans. On their visit to the cave, Urák and his colleagues estimated there were about 69,000 T. domestica and more than 42,000 P. vagans specimens. DNA analyses for the new research also confirmed that these are the dominant species in the colony, Urák said.

Sulfur Cave's spider colony is one of the largest ever documented, and the species involved weren't previously known to assemble and cooperate in this way, Urák said. T. domestica and P. vagans are widespread near human dwellings, but the colony is "a unique case of two species cohabiting within the same web structure in these huge numbers," he said.

Scientists would normally expect barn funnel weavers to prey on P. vagans, but the lack of light in the cave may impair the spiders' vision, according to the study.

The spiders instead eat non-biting midges, which in turn feast on white microbial biofilms — slimy secretions that protect microorganisms against threats in their environment — from sulfur-oxidizing bacteria in the cave. A sulfur-rich stream fed by natural springs flows through Sulfur Cave, filling the cavern with hydrogen sulfide and helping microbes, midges and their predators survive, the researchers wrote in the study.

The spiders' sulfur-rich diet influences their microbiomes, causing them to be significantly less diverse than the microbiomes of spiders from the same two species outside the cave, gut content analyses revealed. Molecular data also showed that the spiders inside the cave were genetically different from their relatives living outside, suggesting the cave-dwellers have adapted to their dingy surroundings.

"Often, we think we know a species completely, that we understand everything about it, yet unexpected discoveries can still occur," Urák said. "Some species exhibit remarkable genetic plasticity, which typically becomes apparent only under extreme conditions. Such conditions can elicit behaviors that are not observed under 'normal' circumstances."

It's important to preserve the colony, despite challenges that might arise from the location of the cave between two countries, Urák said. In the meantime, the researchers are working on another study that will reveal further clues about Sulfur Cave's inhabitants, he added.

This gilt-copper nose ornament, discovered at the archaeological site of Loma Negra in northern Peru, depicts the important Moche deity Ai Apaec, also known as the Decapitator. The ornament is inlaid with accents of turquoise and black stones for his pupils.

In Moche mythology, Ai Apaec was the supreme creator, a deity who had the power to subdue and restore order. In art from the time, he is commonly depicted with a human face, jaguar fangs, and a spider-like body, along with a ceremonial knife called a tumi in one hand and a decapitated human head in the other to represent his power to subdue.

The Moche, also known as the Mochicas, lived on the coast of northern Peru from A.D. 200 to 900, prior to the rise of the Inca Empire. This piece of jewelry was found at Loma Negra, a rich Moche site near the Ecuadorian border. Hundreds of gold, silver and copper artifacts were looted from tombs at Loma Negra in the late 1960s, but many of them, including this ornament, were eventually donated to the Metropolitan Museum of Art in New York City.

The Decapitator ornament measures 2.8 by 3.9 inches (7 by 10 centimeters) and was made out of a sheet of gilded copper. Semiprecious stones accentuate the Decapitator's eyes, earrings and belt. Ai Apaec also wears a large, silver nose ornament. The tiny figurine was likely attached to a piece of silver so that someone could wear it as a nose ornament. But because most of the Loma Negra artifacts were looted from graves, it is unclear whether this ornament was associated with a specific person.

Archaeologists have found that the Moche practiced human sacrifice to honor their gods. This ritual was performed for political reasons, such as the killing of captured enemies, but recent research has shown that family members were also sometimes sacrificed to their high-status relatives.

The Decapitator is closely associated with spiders in Moche iconography, but experts are unsure exactly why. According to The Met, "perhaps the manner in which spiders trap their prey in a web and liquefy their internal organs was considered analogous to the Moche practice of prisoner capture and sacrifice by bloodletting."

For more stunning archaeological discoveries, check out our Astonishing Artifacts archives.

Nocturnal spiders have been filmed capturing fireflies and keeping them in their webs to attract more prey, even intermittently checking on them over the course of an hour, according to a new study.

When fireflies were kept on the webs, sheet web spiders attracted significantly more prey than without the bioluminescent beetles, leading researchers to think the spiders are purposefully using the fireflies as bait to increase hunting success.

"Our findings highlight a previously undocumented interaction where firefly signals, intended for sexual communication, are also beneficial to spiders," study lead author I-Min Tso, a researcher at Tunghai University who studies spider behavior, said in a statement.

"This study sheds new light on the ways that nocturnal sit-and-wait predators can rise to the challenges of attracting prey and provides a unique perspective on the complexity of predator-prey interactions," Tso added.

The researchers had noticed sheet web spiders (Psechrus clavis) — which build their sheet-like webs close to the ground — had accumulated a number of winter fireflies (Diaphanes lampyroides), and thought these glowing bugs may have been used as a visual lure. To find out, the team developed a series of field experiments, placing LED lights resembling fireflies and sheet spider webs, and left other webs empty as controls.

Related: Diving bell spider: The only aquatic arachnid that creates a web underwater to live in

The findings, published Thursday (Aug. 28) in the Journal of Animal Ecology, revealed the LED webs attracted three times more prey than the empty webs. When just looking at the number of fireflies caught, the LED webs snared 10 times more than the non-LED webs.

Sheet web spiders, found in subtropical forests of East Asia, normally sit in the dark, waiting for prey to approach. Footage captured by the researchers shows that if another insect, such as a moth, is caught, the spiders eat it immediately. But the fireflies were left for up to an hour before being consumed, which is about the same amount of time that a female firefly emits a glow in a fixed location, the authors wrote in the study.

Most of the captured fireflies were male, which the authors say may indicate males mistook the stationary glow for potential mates.

The researchers think the spiders — unlike other sit-and-wait predators that have developed their own bioluminescence, like anglerfish — have worked out how to exploit fireflies' sexual cues to their advantage.

"Handling prey in different ways suggests that the spider can use some kind of cue to distinguish between the prey species they capture and determine an appropriate response," Tso said. "We speculate that it is probably the bioluminescent signals of the fireflies that are used to identify fireflies enabling spiders to adjust their prey handling behavior accordingly."

Spider quiz: Test your web of knowledge

Scientists have had to create an entirely new spider genus after four new tarantula species were found to have such long genitalia that they couldn't fit into any pre-existing category.

The team believe the males have evolved this impressive appendage to keep themselves as far away as possible from aggressive females, which are known to eat their partners during mating.

Male tarantulas' genitals are typically 1.5 to two times the length of their head and thorax put together. But the newfound spiders' palps — specialized appendages to transfer sperm during mating — are four times as long as their upper bodies and almost half as long as their longest legs, according to a new study.

"The males of these spiders have the longest palps amongst all known tarantulas," study lead author Alireza Zamani, an arachnologist at the University of Turku in Finland, said in a statement. "Based on both morphological and molecular data, they are so distinct from their closest relatives that we had to establish an entirely new genus to classify them, and we named it Satyrex."

The name Satyrex is a combination of the words "satyr" and "rex." In Greek mythology, a satyr is a male nature spirit with the upper body of a human and the lower body of a goat or horse, and "rex" is the Latin word for king. According to the statement, satyrs are often depicted as having exceptionally large genitalia.

The newfound tarantulas live in burrows and cool spaces between rocks on the Arabian Peninsula and the Horn of Africa. Zamani and his colleagues first encountered Satyrex arabicus in Saudi Arabia, photographed Satyrex ferox in Yemen and Oman, and described Satyrex somalicus and Satyrex speciosus in Somaliland. They published their findings July 22 in the journal ZooKeys.

Related: We now know why tarantulas are hairy — to stop army ants eating them alive

Of the four newfound species, S. ferox stands out as the largest and fiercest, hence its name. Both males and females have leg spans of about 5.5 inches (14 centimeters), and males' palps stretch an incredible 2 inches (5 cm) long, possibly to provide a safety buffer against cannibalistic females during mating.

"We have tentatively suggested that the long palps might allow the male to keep a safer distance during mating and help him avoid being attacked and devoured by the highly aggressive female," Zamani said.

The species is also highly defensive. "At the slightest disturbance, it raises its front legs in a threat posture and produces a loud hissing sound by rubbing specialized hairs on the basal segments of the front legs against each other," Zamani explained.

Molecular and phylogenetic analyses, where scientists reconstruct the evolutionary history of a species through genetics, revealed that a tarantula previously assigned to the genus Monocentropus is in fact more closely related to Satyrex spiders, too. Researchers first described Monocentropus longimanus from Yemen in 1903, but the spider has now been reclassified as Satyrex longimanus.

"The much longer palps of S. longimanus and the four newly described species were among the primary characters that led us to establish a new genus for these spiders, rather than place them in Monocentropus," Zamani said. "At least in tarantula taxonomy, it seems that size really does matter."

Spider quiz: Test your web of knowledge

Filmmakers have captured first-of-its-kind, spine-chilling footage of young spiders cannibalizing their mothers and other elderly relatives en masse.

In the video, more than 1,000 young African social spiders (Stegodyphus dumicola) creep out of their nest in search of their next meal. The youngsters appear to play a macabre game of "statues" as they move, before suddenly freezing then moving again in unison.

The young spiders first attack and devour an insect caught in the giant web that holds their nest, tearing at its body while the insect is still alive. But when this source of food runs out, the spiders turn to one of the moms of the nest, whose condition is deteriorating fast after producing so many young.

"The demands of parenthood are finally taking their toll," British biologist and broadcaster Sir David Attenborough says in his narration of the clip, which is from a new five-part series from the BBC called "Parenthood."

Related: Starving cannibalistic spiders won't hunt their siblings, but they'll quickly dine on their corpses

But the dying spider mom has a departing gift: Trembling, she waits for her offspring and their cousins to swarm and cannibalize her. "Her's is the ultimate sacrifice, born out of a need to ensure the survival of the next generation," Attenborough says.

Scientists think African social spider moms tremble on purpose while waiting for their gruesome deaths. The vibrations they create may be similar to those made by insects that get caught in the web, so young spiders don't hesitate to attack their moms.

However, after eating the spider mom, the spiderlings still aren't satiated. They move on to their other surviving relatives, "eating every adult in the colony one by one until the next generation is all that is left," Attenborough says.

The clip is the first time TV cameras have captured this stomach-churning behavior, according to The Guardian. Attenborough was both "delighted and horrified" when he saw the footage, Jeff Wilson, the producer and director of "Parenthood," told the newspaper.

"When you step away from it and from the horror of it, it sort of makes sense," Wilson said.

Name: Sparklemuffin peacock spider (Maratus jactatus)

Where it lives: Wondul Range National Park, Queensland, Australia

What it eats: Small insects and arthropods

Why it's awesome: These colorful critters don't just dress to the nines to woo their mate. Males also do a sexy shimmy to dazzle the ladies.

Measuring no bigger than 0.2 inches (0.5 centimeters), the sparklemuffin peacock spider is, arguably, one of the cutest spiders around. These jumping spiders were discovered as a new species in 2015.

Females are a dull brownish gray but — like their namesake, the peacock — male sparklemuffins pull out all the stops in the outfit department. With their striking red and blue backs, they look similar to kicking peacock spiders (Maratus calcitrans) and fingers peacock spiders (Maratus digitatus).

But they have a secret up their sleeve that makes them unique: a small flap on the side of their abdomen that they can extend to show off iridescent blue scales.

In case their gaudy garb isn't enough to impress, the males also know how to bust a move. Their Latin name (jactatus) means "rocking" or "jolting" because of the thrusting dance they perform for prospective mates.

Related: Surprisingly-bad acting is key to jumping spider's survival

During courtship, males unfold their fan — a flap on their abdomen used in courtship — and tilt it to one side. At the same time, they lift up their third leg on the same side, lower it slowly then whip it back up, like someone teasing a dog by dangling its toy just out of reach. This jerking motion makes their whole body waggle around, creating vibrations that the female can sense through the ground.

"When [the male] got within a few centimeters of the female, he exploded into a firework of activity," entomologist Jürgen Otto, who wrote the paper describing the species and runs the website Peacock Spider, previously told Live Science.

The species was discovered by a graduate student called Madeline Girard who nicknamed it "sparklemuffin." She discovered another species at the same time and gave it the moniker “Skeletorus” because of its striking black and white markings that look like a Halloween skeleton costume.

Otto believes there could still be many more species of peacock spider out there. "Despite the large number of species we have discovered just in the last few years, I can't help feeling that we may have just scratched the surface of this most exciting group of spiders," he said, "and that nature has quite a few more surprises in store."

Editor's note: This story was updated at 12:40 p.m. ET to correct a measurement conversation.

The biggest male funnel-web spider ever recorded — a deadly behemoth measuring 3.6 inches (9.2 centimeters) from foot to foot — has been handed into a zoo in Australia. The spider is so large, its fangs could pierce and deliver their lethal venom through a human fingernail, zoo keepers said.

Sydney funnel-web spiders (Atrax robustus) are some of the most venomous spiders in the world. If untreated, a single bite can kill a small child within 15 minutes and an adult within three days.

A member of the public caught and donated the giant arachnid to the Australian Reptile Park in Somersby, New South Wales. The zoo encourages donations to support its spider venom program, which produces life-saving antivenom against Sydney funnel-web spider and other spider bites.

Emma Teni, the spider keeper at the Australian Reptile Park, named the giant spider "Hemsworth" after the Australian actors Luke, Chris and Liam Hemsworth. Before Hemsworth, the record for the biggest male funnel-web spider belonged to a 3.1-inch (7.9 cm) arachnid called Hercules.

"We're used to having pretty big funnel-web spiders donated to the park, but receiving a male funnel-web this big is like hitting the jackpot," Teni said in a statement shared with Live Science.

Related: Drug inspired by spider venom aims to reverse heart attack damage

Male funnel-web spiders are typically smaller than females, but they are more dangerous due to a chemical in their venom called atracotoxin that affects the nervous system of humans and monkeys (it doesn't affect other mammals). Females lack this chemical, which likely explains why males are responsible for all 13 recorded deaths from funnel-web spider bites and most of the medically serious bite cases, according to the Australian Museum.

There have been no reported deaths from funnel-web spider bites since the introduction of an antivenom in 1981. The Australian Reptile Park is the only facility in Australia that milks funnel-web spiders for raw venom, and the resulting antivenom saves up to 300 lives per year, according to the statement.

The Australian Reptile Park has designated spider drop-off points dotted around Sydney, the Central Coast and Newcastle. Staff collect the spiders and milk them weekly before sending off the venom to a laboratory that makes the antivenom, according to the statement.

But milking spiders is a tedious process. "It takes about 150 to 200 milkings to create one vial of antivenom," Teni said in a video interview. "We can only milk the male funnel-web spiders, because of the presence of the atracotoxin in their venom."

Therefore, Hemsworth is a very welcome addition to the park's spider stock. "Because Hemsworth is so big, his fangs are massive and he produces so much venom," Teni said. When keepers first saw Hemsworth, "we thought for sure he had to be a female because of his size," she said, "but upon closer inspection, he's a boy."

There are an estimated 50,000 species of spider living on Earth, from behemoths like the giant huntsman and goliath birdeater, down to the tiniest, the dwarf orb weaver and Patu digua. In this extract from "The Lives of Spiders: A Natural History of the World's Spiders" (Princeton University Press, 2024), author Ximena Nelson looks at the three species with unusual diets — plants, blood and pill bugs.

Vegetarian spider

Scientific name: Bagheera kiplingi

Family: Salticidae

Body length: 1∕5–¼ in (5–6 mm)

Notable anatomy: Males have iridescent green markings on cephalothorax and abdomen

Memorable feature: Primarily vegetarian

A spider is an unlikely vegetarian, but Bagheera kiplingi almost fits the bill. Supplementing its diet with nectar, ant larvae, and nectar-feeding flies, this jumping spider feeds almost entirely on Beltian bodies, the detachable fat and protein-rich leaf tips of Vachellia acacia shrubs.

Bagheera is so dependent on Beltian bodies that it is an obligate resident of Vachellia plants, where it lives in areas that are not well patrolled by the resident Pseudomyrmex ants. There is such host specificity to the plant that the spider’s geographic range is limited by the presence of Vachellia.

Plant mutualisms

Ants can be helpful to plants because they tend to be aggressive and keep herbivorous insects away. Consequently, many plants make an effort to lure ants as bodyguards and keep them around by producing accessible nectar through extrafloral nectaries. This continuous source of food is irresistible to ants, but often is also exploited by spiders, especially wandering spiders that roam to hunt their prey.

This includes many species of jumping spiders, where nectarivory may be a common tactic to obtain a meal with less risk of injury than hunting. Nectarivory can increase spider longevity and reproductive output. Importantly, for the tiny spiderlings, nectar may provide much-needed energy that allows them to hunt prey inevitably larger than themselves. In addition to extrafloral nectar, Vachellia species produce nutritious Beltian bodies to keep Pseudomyrmex ants nearby.

Related: We now know why tarantulas are hairy — to stop army ants eating them alive

The defense put up by the ants is formidable, and few animals can encroach it. Bagheera exploits the mutualism by harvesting the Beltian bodies and extrafloral nectar produced by the acacia without providing defense to the plant. Being able to see ants from a distance, Bagheera largely seems to avoid encounters with them — unless craftily stealing a larva being carried by one.

An unusual diet

Depending on location, plant-derived food accounts for between 60 and 90% of Bagheera’s diet, making this the only near-herbivorous spider known and a rather extreme outlier in a group known for its predatory behavior. As spiders cannot ingest solids, the Beltian bodies must be enzymatically broken down prior to being consumed, which can happen in a matter of minutes. Although this may be an easily available source of food, the spiders appear to need a lot of it to get by: They feed on many Beltian bodies in a single feeding bout, and about 30 Beltian bodies are required to provide the nutrition of a single insect prey.

Vampire spider

Scientific name: Evarcha culicivora

Family: Salticidae

Body length: 1∕8–2∕5 in (3–10 mm)

Notable anatomy: Males have bright-red band under forward–facing eyes

Memorable feature: Specializes in hunting the vectors of Anopheles (malaria) mosquitoes

Living in the Lake Victoria region of Africa, Evarcha culicivora is possibly the pickiest animal on Earth. The media-named "vampire spider" does not feed directly on human blood, but does so indirectly by preying on blood-fed female mosquitoes. In fact, Evarcha actively chooses Anopheles mosquitoes, which are attracted to feed on human blood and are hence vectors of malaria.

By feeding on blood-fed female Anopheles at a time of day when the mosquitoes tend to rest after a blood meal, sexually mature spiders attain a "perfume" that makes them alluring to the opposite sex. This suggests that, unusually, their prey preference may be at least partly driven by sexual selection. As a coup, E. culicivora may play a small role in mitigating the transmission of malaria by preventing mosquitoes carrying the parasite from biting and infecting another person.

An affinity for blood

The vampire spider has an approximate hierarchy of preferences, with blood-fed female Anopheles at the top, followed by other kinds of local blood-fed female mosquitoes, then non-blood-fed female Anopheles, male Anopheles, and finally the most common prey type in its habitat: midges. Juveniles even have an Anopheles-specific method of hunting, which they don’t use for other prey. Odors associated with humans may attract the spiders to houses, where they are likely to encounter the Anopheles, but it is their visual decision-making that we understand best.

Anopheles has a specific resting posture, and Evarcha uses this to differentiate it from other mosquitoes. The spider judges how "fat" the abdomen appears as an indication that it is full of blood. To determine sex, it also looks at how feathered the antennae are, as female mosquitoes have barer antennae.

Paradoxical plants

Aside from houses, a popular hunting spot is on Lantana camara shrubs, where mosquitoes sometimes rest and eat nectar. The spiders also feed on Lantana’s nectar, which gives them a nutrition boost that allows them to hunt prey many times their size. Paradoxically, Evarcha’s prey preference is no longer expressed when the spider is exposed to the dominant volatile compound of Lantana, β-caryophyllene. This is because the plant odors reduce the time Evarcha spends visually assessing its prey. The fact that the spider is prone to identification errors of its preferred prey illustrates a trade-off in Evarcha’s ability to process information when faced with a diversity of stimuli involving multiple sensory modalities.

Woodlice-eating spiders

Scientific name: Dysdera crocata

Family: Dysderidae Females

Body length: Females c. ½–c. 3∕5 in (11–15 mm), males c. 2∕5 in (9–10 mm)

Notable anatomy: Has very noticeable and broad chelicerae

Memorable feature: Specializes in hunting woodlice

Woodlice are terrestrial crustaceans (isopods) with a thick carapace, which they use as a shield when they roll into a ball or cling to a surface to avoid attack. Despite being slow-moving, many species have noxious secretions, making them formidable foes. Some spiders in the genus Dysdera, the most famous being Dysdera crocata, are among the few predators to hunt them.

Pincer, fork and key

Species that specialize in catching woodlice have specially adapted chelicerae. Unlike nonspecialist Dysdera species, these specialists use one of three main tactics to grasp prey: the pincer, the fork, and the key. Each strategy is associated with a particular mouthpart morphology.

Species with elongated chelicerae, like D. crocata, use the pincer approach, rapidly penetrating the unprotected underside of a woodlouse with one chelicera before it can roll up and defend itself, while simply holding the armored side to keep the prey in place. If the woodlouse manages to roll into a ball or cling hard, the spider patiently waits, unmoving and ready, until it gets another chance to attack.

The fork tactic is used by species that have chelicerae with a concave upper surface. Here, attacks consist of quicky grabbing the woodlouse with its first pair of legs, slipping the chelicerae under the isopod, and rapidly biting the underside of the woodlouse before it has time to adopt a defensive posture. The key tactic requires flattened chelicerae. Like fitting a key into a lock, the spiders slide one chelicera between the armored segments of the carapace of the woodlouse, inserting its fang to bite — voilà!

Woodlice gradient

Of the Dysdera species that largely consume woodlice, there is variation in how much they rely on these prey. However, it is likely that all need to eat at least some woodlice to grow and develop quickly, suggesting a metabolic need for this food source. Furthermore, there is a correlation between the level of modification of the chelicerae and woodlouse specialization, with those that are almost obligate specialists having the most strongly reshaped mouthparts. This is matched by behavior, with species with less modified mouthparts exhibiting markedly less prey preference, and by their ability to extract key nutrients from their prey.

Adapted from THE LIVES OF SPIDERS: A NATURAL HISTORY OF THE WORLD’S SPIDERS. Copyright © 2024 by Ximena Nelson. Reprinted by permission of Princeton University Press.

Tarantulas are hairy so that the army ants cleaning their homes don't eat them alive, a new study suggests.

The study, published Aug. 6 in the Journal of Natural History, proposes several new ideas about tarantula relationships with other species, including their surprisingly passive but still occasionally violent interactions with predatory ants.

Predatory ants, or army ants, are known to hunt spiders alive, but when these ants were observed scavenging for food in South American tarantula burrows, the ants tended to ignore adult tarantulas as well as tarantula offspring. In the rare instances when the ants did attack, the tarantulas' stiff hairs offered adequate protection.

"The dense hair covering the tarantula's body makes it difficult for the ants to bite or sting the spider," study lead author Alireza Zamani, an arachnologist at the University of Turku in Finland, said in a statement. "Therefore, we believe that the hairiness may have evolved as a defence mechanism."

Related: Deadly male funnel-web spider 'Hercules' breaks record as biggest ever discovered

Zamani and his colleagues explored the complex relationships between tarantulas and other animals by reviewing previous scientific studies and gathering new observations from the field and social media.

The researchers found that army ants help fossorial tarantulas — those that live in burrows — by removing old food from their burrows. However, the spiders still needed protection in case the ants got bitey. This hair-defense hypothesis is supported by previous studies that suggested burrowing tarantulas cover their egg sacs in hairs to help stop ants from getting at them.

Furthermore, the team discovered that less hairy — and therefore potentially more vulnerable — arboreal tarantulas, including Avicularia hirschii in Peru, have developed different defense strategies against ants. For example, in one observation, the researchers watched A. hirschii hang from the tip of a leaf to escape ants on the hunt for prey, according to the statement.

While tarantula-ant relationships can get strained, the researchers found that tarantulas enjoy friendlier interactions with amphibians, which sometimes live in their burrows. The study described more than 60 partnerships between tarantulas and amphibians across 10 different countries, as well as relationships with snakes and other spiders.

"Apparently, the frogs and toads that live within the retreats of tarantulas benefit from the shelter and protection against their predators," Zamani said. "In turn, they feed on insects that could be harmful to the spider, its eggs, and its juveniles. It seems that tarantulas might not be as scary and threatening as their reputation suggests."

Researchers have discovered how the brain of the largest animal group evolved after finding the remains of a microscopic, worm-like creature that lived half a billion years ago. 

The creature died while still in its early development, or larval stage, and belongs to a new species named Youti yuanshi, which combines the standard Chinese words "yòutǐ," meaning "larva," and "yuánshǐ," meaning "primitive," according to a new study published Wednesday (July 31) in the journal Nature. 

Y. yuanshi inhabited the Cambrian seas and helped give rise to living arthropods like insects, spiders and crabs. Despite being about the size of a grain of sand, the fossil is exceptionally well-preserved, revealing never-before-seen details that help explain how arthropods developed complex brains. 

"When I used to daydream about the one fossil I'd most like to discover, I'd always be thinking of an arthropod larva, because developmental data are just so central to understanding their evolution," study lead author Martin Smith, an associate professor in paleontology at Durham University in the U.K., said in a statement. "But larvae are so tiny and fragile, the chances of finding one fossilised are practically zero — or so I thought!" 

Related: Stunning 3D images show anatomy of 500 million-year-old Cambrian trilobites entombed in volcanic ash

A team of researchers recovered the fossil from the Yu'anshan rock formation in the Yunnan Province of China. They scanned the fossil with X-rays to create virtual 3D images of its internal structures. The images revealed a brain and primitive circulatory system, including traces of nerves serving the larva's simple legs and eyes, according to the study.

"I already knew that this simple worm-like fossil was something special, but when I saw the amazing structures preserved under its skin, my jaw just dropped — how could these intricate features have avoided decay and still be here to see half a billion years later?" Smith said. 

While researchers aren't sure how the animal became such an exceptional fossil, at some point soon after death, its soft tissues were replaced with phosphate and preserved in rock. Smith told Live Science that there must have been higher levels of phosphorus in the water that provided the raw materials for the creature's cells to be converted into phosphate minerals. 

The exceptional preservation allowed researchers to see more of an early arthropod's anatomy than they normally would. This included signs that arthropod brains were becoming more sophisticated during Y. yuanshi's time. For example, the larva had an ancestral brain region that would become the nub of a more specialized arthropod head with antennae and various other appendages, according to the statement. These specialized heads meant the creatures could adopt a variety of lifestyles, including becoming sophisticated predators. 

"As the arthropod brain has developed, that's allowed arthropods to exhibit much more complicated behaviors and even more complicated morphologies," Smith said. 

This "led to their rapid rise in diversity, which they've maintained to the modern day," he added. 

In the animal kingdom, organisms can be named after anything — an odd behavior, a strange sound and even a funny appearance. The naming system requires all creatures  to have two terms; a name that indicates the genus and species. 

Although limited by certain rules, taxonomists have found a way to show off their sense of humor. From the irregular to painfully pun-full, here are some of the best named animal species.

Aha ha

Meet the wasp whose stinger isn't the only thing that will leave you in stitches — the Aha ha wasp.

In the 1970s, wasp lover and entomologist Howard Ensign Evans spent years collecting wasp specimens to send to his friends for examination and study. After his travels in Australia, Evans sent two specimens to Arnold Menke, a fellow entomologist at the systematic entomology laboratory for the Agricultural Research Center.

Upon opening the parcel, Menke looked at the wasps and exclaimed "Aha! A new species!" to which his colleague, Eric Grissell, responded in disbelief, "ha!". In fact, Menke was right, it was a new genus of wasp belonging to the family, Sphecidae, which are thread-waisted wasps that have skinny waists and paralyze their prey.

Gorilla gorilla

A name so nice, you say it twice. The name of the western gorilla is a tautonym, a scientific name where the genus and species are both the same word.

The western gorilla (gorilla gorilla) is one of two species of gorilla in the world. There are two subspecies. One is the western lowland gorilla (Gorilla gorilla gorilla) while the other is the cross river gorilla (Gorilla gorilla diehli).

The name was inspired by antiquity. Around 2,500 years ago, a Carthaginian admiral called Hanno set sail along the west coast of Africa. He visited a small island where he reported meeting "savage hairy people," which his interpreters called "gorillai," according to reports. 

We cannot be sure what language his interpreters spoke or if the account is actually true. Despite this, American naturalist Thomas S. Savage used the term in the first scientific description of the species - Troglodytes gorilla, now known as the western gorilla.

Boops boop

Much like the western gorilla, the name of this big-eyed species of seabream is a tautonym — Boops boops. In Greek, the name translates to "ox-eyed," and is inspired by the fact that it has large, round eyes relative to its small size.
 

Agra vation

Not many names capture attention like the caribid beetle, Agra vation. Its scientific name hints at both frustration and intrigue.

Conservation biologist Terry L. Erwin created this clever pun based on the difficulties of collecting beetles from the genus Agra.

These beetles are nocturnal, have slender heads and are found high in the rainforest canopy. Erwin devised a technique called "canopy fogging" to collect these species — using thermal foggers and biodegradable insecticide to collect mass quantities of specimens that were difficult to reach.

Before he died in 2020, Erwin was responsible for describing 438 species of Carabidae beetles, with names such as Agra cadabra and Agra katewinslettae (after the famous English actress who starred in the movie "Titanic").

Parastratiosphecomyia stratiosphecomyioides

The southeast asian soldier fly has the longest scientific name of any animal — Parastratiosphecomyia stratiosphecomyioides.

In ancient Greek, its genus translates to "near soldier wasp-fly" and the species translates to "wasp-fly like." The name comes from its resemblance to a thread-waisted wasp — the club-shaped abdomen, long antennae and darkened wings all make it look like a wasp even though it has no stinger. In evolutionary biology, this is known as mimicry.

Hotwheels sysyphus

Meet Hotwheels sysyphus, the spider with a name as unique as its anatomy. Believe it or not, its name is in honor of its distinct genitalia. 

A male specimen of this species was discovered in the southwest of China. Scientists that examined the spider found that the male sported a long and coiled embolus (a tubular organ that inseminates the female) and that it resembled a Hot Wheels track.

The species name, sysyphus, is derived from a figure in Greek mythology. In the tale, the king of Corinth, Sisyphus, is punished by Zeus to endlessly push a rock uphill, only to have it roll back down again. The spider's circular genitalia is reminiscent of Sisyphus' cyclic punishment, ergo its species name.

Boselaphus tragocamelus

Boselaphus tragocamelus is a species with perhaps the best mashup of names from other animals:  'Bos' is Latin for ox, 'elaphos', is Greek for deer, 'tragos', is Greek for a male goat, and 'kamelos', is Greek for camel.

B. tragocamelus is actually a large bovid found in India and Nepal. It is one of the largest living antelopes in the world — males can reach a towering height of 6.8 feet (2.1 meters).

This species was first described in 1766 by German zoologist Peter Simon Pallas, who said its appearance was similar to a bunch of other animals, according to an article in the American society of mammalogists. The oddball sports a humped back like a camel, a horned and slender head like a goat or deer and a body shape similar to a cow. 

Gelae baen

Gelae baen, gelae donut and gelae rol are small, round fungus beetles pronounced like the english word "jelly" and whimsically named after sweet treats. The genus, Gelae, is derived from the Latin word "gelatus," which means "jellied" or "congealed." It's an homage to the beetles' diet of fungal slime molds.

Han solo

Other species have been named after characters from films, including the extinct trilobite Han solo, named after the famous "Star Wars" pilot.

In 2005, biologist Samuel Turvey described a trilobite found in  China's Hunan province. According to the study, the genus name Han was given to honor the Han people of China. The fossil was suspected to be the last surviving member of the family, Diplagnostidae, which gave rise to the species name solo. 

Later on, Turvey revealed that his friends dared him to pick that name as they believed most of the characters' names in the franchise sound like scientific names.

Scrotum humanum

One of the first dinosaurs ever described was almost named after human testicles.

In 1763, the lower end of a femur was found and described as Scrotum humanum because of its resemblance to human testicles, according to a 2014 article in the journal Science Vision.

It was first discovered nearly a century earlier in the Taynton Limestone Formation in Oxfordshire, England. Eventually, the curator of the Ashmolean Museum, Robert Plot, published an illustration of the fossil in the "Natural History of Oxfordshire." The fossil fragment's large size led him to believe it belonged to a Roman war elephant or a giant human.

In 1763, physician Richard Brookes dubbed it "Scrotum humanum" and republished the new name in his book, "The Natural History of Waters, Earths, Stones, Fossils and Minerals etc."

It was until 1824 that geologist William Buckland discovered that the fossil was part of an extinct reptile. He determined it may have once been part of a Megalosaurus, based on similarities to other giant fossil bones he had found. 

Although the name S. humanum is not used today, in 1970 paleontologist Beverley Halstead argued that because it was published first and it followed the naming convention, it should still be accepted.

Irritator challengeri 

The not-so-subtle name of this dinosaur is a reflection of paleontologists' frustration when they discovered someone had tampered with their fossil. 

Paleontologists identified Irritator challengeri based on a partly crushed skull found in the Santana Formation in Brazil. The skull was excavated and sold illegally in 1996 by commercial diggers. The scientists who described the species relied on CT scans to piece together the original skull shape.

The scans revealed the fossil was heavily damaged during collection and that it had an artificially constructed snout and a crack in the center of the skull that had been filled with car body filler.

Sphenacodon ferox and Sphenacodon ferocior 

The genus Sphenacodon contains two species of early reptilian predators in the ultimate showdown for the best name: Sphenacodon ferox versus Sphenacodon ferocior, otherwise known as "fierce" and "more fierce," respectively.

In 1878, Yale paleontologist Othniel Charles Marsh described the first species in the genus Sphenacodon from a section of a lower jaw found in northern New Mexico. In Greek, "sphenacodon" translates to "wedge-point tooth," based on the large, sharp teeth that were in the jaw. Because of these fearsome teeth, Marsh assigned it the species name "ferox," which means "fierce" in Latin.

In 1937, Alfred Sherwood Romer, a specialist in vertebrate evolution, described another species from a skull and a number of vertebrae found near Jemez Canyon in New Mexico. He described this species as morphologically similar to S. ferox but with a body size up to 40% larger and longer spines.

Preseucoila imallshookupis 

Entomologist Matthew Buffington named the genus of this wasp species, Preseucoela, by combining Elvis Presley's last name with the suffix "-eucoela" — a word French naturalist Jean-Jacques Kieffer used to describe parasitic neotropical wasps, according to the 2004 study where the species was described. The species name is an homage to The King's famous 1956 song "All Shook Up."

Ampulex dementor

Ampulex dementor is a species of wasp in the family Ampulicidae. These cockroach wasps turn their prey into submissive zombies, according to a 2010 study in the journal Communicative and Integrative Biology. 

The species name "dementor" comes from the fictional "dementors" from the "Harry Potter" series. Dementors are soul-sucking, dark creatures that feed on human happiness, leaving their victims in a vegetative state.

Like its namesake, A. dementor injects cockroach brains with a toxin that keeps the cockroach alive but in a zombie-like state. The wasp then deposits its eggs into the cockroach's body. Once hatched, the young wasp larvae burst out and feed on the remains of the cockroach.

Sollasina cthulhu 

Sollasina cthulhu is a 430 million-year-old relative of living sea cucumbers. This tentacled critter lived on the bottom of the seafloor, crawling around on its 42 tubed feet to scavenge for food.

Because of its appearance, the species was named after a fictional deep-sea character from the fantasy short story "The Call of Cthulhu," by H. P. Lovecraft. The Cthulhu was a tentacle-headed monster that slumbered in a city at the bottom of the Pacific Ocean. 

Scientists first named the species in a 2019 study in the journal Proceedings of the Royal Society B. Researchers described a perfectly preserved fossil specimen found in the Herefordshire Lagerstätte formation in the United Kingdom. A 3D reconstruction of the fossil helped pin down the creature as a distinct species.

Ajnabia odysseus

Ajnabia odysseus is the first duck-billed dinosaur to be found in Africa. It is a hadrosaur that lived during the Late Cretaceous period, around 66 million years ago.

At that time, the world was split into two main supercontinents: Laurasia (North America, Asia and Europe) in the Northern Hemisphere and Gondwana (South America, Africa, Antarctica and Australia) in the Southern Hemisphere.

Until the discovery of A. odysseus, scientists thought hadrosaurids lived only on the isolated supercontinent of Laurasia, because it was surrounded by deep waters, according to a 2010 article in the Zoological Journal of the Linnean Society.

The African fossil challenged the understanding of the dinosaur family's dispersal, as it showed that a hadrosaur had crossed miles of ocean to reach Gondwana, according to the 2021 study describing the species.

This long journey led the researchers to name the species after the ancient Greek hero Odysseus, who famously embarked on a 10-year voyage home from Troy.

Geophilus persephone

Geophilus persephone is a cave-dwelling centipede that spends its entire life in complete darkness. 

G. persephone was discovered in underground caves in France in the 1990s. It is named after the queen of the underworld in Greek mythology, in which Persephone was abducted by her uncle, Hades, god of the underworld, who abducted her as his bride.. 

This species has a slender body, no eyes, and only 29 legs. It was the first soil centipede to be described as a troglobite, a species strictly bound to underground habitats.

Geophilus hadesi

In 2015, scientists described another underground species of soil centipede: Geophilus hadesi. It has adapted to cave life, thriving in complete darkness and high humidity.

G. hadesi is the deepest-dwelling centipede in the world, found at a record 3,609 feet (1,100 m).

Hydra viridissima

Hydra is a genus of small freshwater animals with tubelike bodies and tentacles. They grow up to 0.4 inch (10 millimeters) long and eat worms, fish larvae and small crustaceans.

They can regrow lost limbs and even grow a whole new organism from small tissue fragments. Their bodies are made mainly of stem cells, allowing these creatures to constantly replace old cells and seemingly live forever.

The genus takes its name from the monster in Greek mythology. The serpent-like beast had many heads and was bred to kill Hercules; when one head was cut off, two heads would grow back in its place. 

This species is named viridissima, which in Latin means "the greenest." It's bright green appearance comes from its symbiotic relationship with an algae called Chlorella, that lives within its body.

Hoopoe

The Eurasian hoopoe is a bird with a bold appearance and a unique call. 

Its Latin name is an onomatopoeia created from the "oop-oop-oop" sound of its call, according to the Helm Dictionary of Scientific Bird Names. 

Giant, invasive Jorō spiders have spread across several U.S. states during the last decade. Now, scientists have discovered these palm-size critters are potentially much more tolerant to living in cities than other species and appear to thrive alongside major roads, which could help give them a foothold (or eight) in major cities along the Eastern Seaboard.

Jorō spiders (Trichonephila clavata) are a species of orb-weaving spiders — a group known for creating highly symmetrical, circular webs. Jorōs are easily recognizable thanks to the distinctive yellow bands that adorn their otherwise black legs. They also build unique webs that can be more than 6 feet (1.8 meters) across and appear golden when they reflect sunlight. 

Female Jorōs, which can grow to around 3 inches (7.6 centimeters) across — around double the size of males — also have blue stripes and red patches on their predominantly yellow abdomens. 

After mating in early autumn, female Jorōs lay large, web-bound clusters of up to 400 eggs before dying off at the start of winter, along with the males. When the eggs hatch in spring, the baby spiders create parachute-like webs that enable them to fly up to 100 miles (160 kilometers) away from where they were born. 

Jorō spiders are endemic to Asia, and until recently they were only found in Japan, Korea, Taiwan and China. However, in 2014, researchers spotted several Jorōs in the U.S. near Atlanta, Georgia. Experts believe these invasive individuals were accidentally brought to the U.S. inside a shipping container, according to a 2015 study. 

In the years since, Jorō spiders have quickly multiplied and spread in the U.S. thanks to their ability to widely disperse after birth. They are now found across Georgia, as well as in South Carolina, North Carolina and Tennessee. Additional sightings have also been reported in Alabama, Maryland, Oklahoma and West Virginia, and experts believe they could spread across the entire U.S. East Coast in the future.

Related: What is the deadliest spider in the world?

Since their arrival, researchers have noticed that Jorō webs are often located in close proximity to major highways. This is surprising because the vibrations caused by busy roads normally interfere with spiders' ability to hunt: When smaller critters get trapped in spider webs, they struggle to get free, which alerts the spiders to their presence, but busy roads can drown out these vibrations. Spiders are also very sensitive to vibrations in general.

In a new study published Feb. 13 in the journal Arthropoda, researchers investigated how vibrations impacted Jorō spiders. In the laboratory, the study team used tuning forks to simulate the vibrations given off by highways to see how it impacted the arachnids' ability to hunt simulated prey placed in their webs.

Across 350 trials, vibrated Jorōs attacked simulated prey 59% of the time, while non-vibrated Jorōs pounced on the dummy prey 65% of the time. The trials also showed that the "roadside" spiders were able to maintain a similar healthy body weight to the other spiders, indicating that the vibrations were not impacting them in the long term.

"The spiders seem to be able to make a living there," lead study author Andy Davis, an ecologist at the University of Georgia, said in a statement. They are surprisingly "urban tolerant," he added.

It is unclear what long-term effects Jorō spiders will have on the ecosystems they invade. Last year, researchers revealed that the spiders are unusually shy and non-aggressive toward other spiders. However, without a natural predator seeking them out, their numbers will likely continue to rise, which could help them outcompete other species for resources.  

But whatever their ecological effects, the new findings suggest these arachnid invaders aren't going anywhere anytime soon.

"I don't know how happy people are going to be about it, but I think the spiders are here to stay," study co-author Alexa Schultz, a third-year ecology student at the University of Georgia, said in the statement. And they could end up in places "where you wouldn’t imagine a spider to be," she added.

Discover the fascinating world of camouflage and masterful mimicry in this gallery of hidden animals. From elusive snow leopards to tiny mantises, these animals of all shapes and sizes can blend seamlessly into their environments. 

Walking leaves

Just a photo of leaves? Take a closer look …

Found across Asia, three leaf insects (Cryptophyllium westwoodii) cling to the wooden branches of a plant. 

Hidden beneath the sand

The venomous horned rattlesnake (Crotalus cerastes) is a master of disguise. Hidden deep within the sand, it waits patiently for its prey to come near before striking. It is sometimes called the sidewinder rattlesnake because it throws its body sideways across the ripples in the sand to move around very quickly.

Somewhere in this photo, a golden eye can be seen peeking out from beneath the sand.

Pygmy seahorse

Hippocampus bargibanti was the first pygmy seahorse described in the world. As the name suggests, pygmy seahorses are incredibly tiny, only growing to 0.8 inch (2 centimeters) in length. They seamlessly blend into the coral in the ocean. 

A family of mallard ducks

Time for a tricky one. Amid this rocky shore, a mother mallard (Anas platyrhynchos) and her three baby chicks are camouflaged perfectly against the terrain.

Almost mistaken as another group of rocks, they sit just left of the two big rocks in the center frame.

Color-changing antics

Chameleons are famous for their camouflage. Their ability to change color is controlled primarily by their top skin layer, which can change its structure to manipulate how light is reflected.

In this photo, a high-casqued chameleon (Trioceros hoehnelii) hides among the lichen- and moss-covered tree bark. 

Lurking in the coral

The most venomous fish in the world is the stonefish (Synanceia verrucosa), and it has a disturbing resemblance to coral-covered rocks in shallow waters.

Look closely, and you may be able to see a face emerge from the coral. 

Peering through the tall grass

A wildcat lurks through the tall grass in this photo. Can you spot it?

Bobcats (Lynx rufus) are quiet hunters that use their dull, dense coats to blend into their surroundings before they pounce at prey. 

Himalayan tahr

In the Himalayas and certain parts of New Zealand, large hoofed and goat-like Himalayan tahrs (Hemitragus jemlahicus) live on the mountain slopes and hillsides. 

Up high in the trees

Spotted coats help leopards (Panthera pardus) blend into tall grass or tree canopies.

Buried for protection

While they rest and digest their food, stingrays use their wings to bury themselves in the sand to hide from predators.

Look closely to spot a pointed tail protruding from the sand.

Wild waved sphinx moth

Hiding in plain sight, the waved sphinx moth (Ceratomia undulosa) rests on the bark of a tree.  

Amidst the rocky terrain

This photo was taken in France's Mercantour National Park after mountain goats were spotted moving across the mountainside. 

Hidden in the tundra

Another challenge: Spot the camouflaged hare, which is nearly invisible among the moss, lichen and rocks in the tundra.  

White-tailed deer

Behind the trees is a group of white-tailed deer (Odocoileus virginianus), which can be found throughout most of North America. 

Although their coats change color from reddish-brown to gray in the winter for camouflage, these deer depend on their excellent hearing and speed to escape large predators such as wolves, bears and mountain lions.

How many do you see?

Hidden woodland songbird

Rightly named a brown creeper (Certhia americana), this tiny, woodland songbird is a common-but-elusive critter in Central America. These birds spiral up and down large trees, looking for loose bark to nest behind. Their brown and speckled bodies make it difficult to find them when they are perched on a tree. 

Concealed in the moors

The mottled brown and tan plumage of this wild mallard helps it blend into its surroundings, providing perfect concealment amid the grass of the moors. 

Mimicking caterpillar

Many insects use camouflage to mimic objects or animals. Many species of caterpillar in the family Geometridae use camouflage to mimic twigs on plants. Some copy not only the shape, but also the color of a twig. 

Mysterious nightjar

Is it a snake? A lizard? No, it's a bird.

The common pauraque (Nyctidromus albicollis) is a type of nightjar. These medium-size birds have pointed wings and long tails and are active only at night.

During the day, this bird sleeps on the open ground, and its unique coloration allows it to remain hidden.

Cloaked stalking tiger

You may have been quick to spot the tiger prowling in the background of this photo, but if you were a deer, it would not have been that easy.

In the wild, tigers prey on many types of deer. Deer's vision is limited to colors on a spectrum between green and blue. This means they don't see the predator as orange, so the tiger would be green and thus hidden in the dried grass. 

Brightly colored crab spider

Camouflaged on the tops of flower heads, the goldenrod crab spider (Misumena vatia) waits, with its legs held out to its sides, for pollinating insects to ambush. These spiders' cryptic colors allow them to hide in white or yellow flowers. 

Devil scorpionfish

The devil scorpionfish (Scorpaenopsis diabolus) is a venomous and well-camouflaged marine fish found in the Indo-Pacific region. It possesses spines with toxic venom for defense and relies on its unique appearance to ambush prey.

This species is known for its intricate patterns and colors, making it a fascinating-yet-dangerous inhabitant of coral reefs.

Seamlessly hidden common sole

The common sole (Solea solea) is a flatfish that lives in the North Atlantic Ocean and Mediterranean Sea. Its upper side mimics the seafloor, blending in with the sand or gravel, while the underside is white to avoid detection from below while it swims. This adaptation helps the sole avoid predators and ambush prey effectively. 

Protection for new born chicks

The pied avocet (Recurvirostra avosetta) is a shorebird that boasts a striking black-and-white pattern and an upturned bill, which the bird uses to sift through sand to find small invertebrates in shallow pools at low tide. 

The chicks have silver-gray feathers, which provide effective camouflage in the avocet's marshy habitat. This plumage helps the bird blend in with its surroundings, offering protection from potential predators. As the chicks grow, their black-and-white coloring will gradually appear.

Amidst the rocky terrain

Let's zoom out for this one.

Known for its shifty nature and distinctive coat, the snow leopard (Panthera uncia) inhabits the steep, rugged terrain of Central and South Asia. The snow leopard has a thick coat, wide paws and a long tail that it uses for balance while climbing mountains.

The king of camouflage

Nestled against the coral sits an octopus, the king of camouflage. These alien-like creatures can not only change the color of their bodies but also mimic textures. 

An unwelcome tagalong

Be careful where you step!

At first glance, this photo may seem like a standard image taken during a hike — but the fallen leaves mask an unwelcome tagalong.

Viperidae is a family of snakes, commonly known as vipers, that are venomous, nocturnal and found all over the world. Some are very colorful. Others, like the one in this photo, are dark and marbled, allowing the snakes to blend into the scattered shadows on the forest floor. 

Insect or plant?

Stick insects are known for their mimicry of twigs or branches. Found in the tropics, these critters have elongated bodies and legs, making the insects tricky to spot among the plants. 

Perched high in the trees

The Eastern screech owl (Megascops asio), native to North America, is a small bird known for its trill-like calls. With a height of around 6 to 10 inches (16 to 25 cm), it comes in two colors: red and gray. These nocturnal hunters often inhabit wooded areas and are cavity nesters, using abandoned nests or tree hollows. 

Amongst the rocks and boulders

You have eagle eyes if you can spot the small bird in this photo.

Oenanthe melanura, commonly known as the blackstart, grows to a maximum height of 5.5 inches (14 cm). It is found in rocky habitats and arid landscapes across Southern Europe and North Africa, and often nests in rock crevices. 

The floral mimicry of an orchid mantis

Orchid mantises (Hymenopus coronatus) look and behave like flowers. This behavior involves swaying from side to side to resemble a flower blowing in the wind. They use this technique for both hunting and hiding. 

A stealthy stalker hidden in the tall grass

The fastest mammal in the world is also one of the best-camouflaged animals. The spots on cheetahs (Acinonyx jubatus) help camouflage their bodies by offsetting shadows against the tall grasses in their habitats. While camouflaged, they can stalk their prey without being seen and protect their cubs from predators. 

Eurasian bittern amongst the reeds

The Eurasian bittern (Botaurus stellaris) is a wading bird known for its elusiveness and camouflaged plumage. Found in wetlands across Europe and Asia, it is known for its booming calls during breeding season. 

Frosty disguise of an arctic hare

The Arctic hare (Lepus arcticus) is adapted to harsh Arctic climates. Known for its white fur in the winter and dark fur in the summer, it has large hind legs and padded feet that hold its weight above thick snow for running swiftly at up to 37 mph (60 km/h).

Mealy amazon parrots

How many can you see?

A group of southern mealy Amazon parrots (Amazona farinosa) is found high in a subtropical forest in Ecuador. 

Long-spinnered bark spider

Can you find the eight-legged trickster hidden in this photo?

This spider is known as a long-spinnered bark spider or two-tailed spider, part of the genus Hersilia. It is named after its large spinnerets, the silk-spinning organ on the back of its abdomen. 

The largest male specimen yet of the most venomous spider in the world has been found in Australia.

"Hercules," a funnel-web spider, is 3.1 inches (7.9 centimeters) from hairy foot to hairy foot, according to the Associated Press — about the same diameter as an Olympic gold medal.

The spider was found about 50 miles (80 kilometers) north of Sydney and taken to a local hospital. The hospital turned the giant arachnid over to the Australian Reptile Park, a zoo in New South Wales that runs a venom-milking program. Venom from spiders and snakes is used to produce antivenom for Australian hospitals.

"Male funnel-webs, once they reach maturity, their natural lifespan is only around one year," Emma Teni, a spider-keeper at the park, said in a video provided by the AP. "So we need to constantly have them handed in by the general public, because we need them for our lifesaving antivenom program."

The male Sydney funnel-web spider (Atrax robustus) has one of the most toxic-to-humans venoms of any spider, according to the Australian Museum. Male spider venom contains a neurotoxin that affects the nervous systems of primates, including humans. Females are also venomous, but their venom does not contain this neurotoxin, according to the museum. Only male bites have caused human deaths.

Since the Australian Reptile Park launched its spider antivenom program in 1981, no one has died from funnel-web spider bites, according to the park. Every week, park staff use glass pipettes to urge spiders to bite so they can suck up droplets of venom. The venom is then frozen and used by supplier CSL Seqirus to make antivenom that can be given to patients who have been bitten.

Related: Why does Australia have so many venomous animals?

Funnel-web spiders are burrowers. They get their names from the networks of "trip wires" they spin at the entrances to their burrows, which are often shaped like a funnel of silk, according to the Australian Museum. They like moist, vegetated areas and are often found in the forested Sydney suburbs. Humans are probably most likely to encounter deadly male spiders, which leave their burrows in the summer months to look for mates.

Hercules is bigger than the Australian Reptile Park's previous record-holding male funnel-web, a specimen nicknamed Colossus who lived at the park in 2018.

Female funnel-webs are typically larger than males, and the largest the park has ever held was "Megaspider," a female donated in 2021 with a leg span of 3.14 inches (8 cm).

Funnel-webs defend themselves aggressively when threatened, rearing up on their hind legs and showing off their 0.8-inch-long (2 cm) fangs. According to the Australian Museum, they are also capable of surviving up to 30 hours underwater by trapping air bubbles around the hairs on their abdomens. Spiders are sometimes found at the bottom of pools and presumed dead, only to recover and scurry away once they dry out.

Doctors can see thousands of patients a year, and sometimes, they encounter cases that completely flabbergast them or else turn out to be incredibly rare. When this happens, they'll often chronicle the cases in medical journals so that clinicians and members of the public alike can learn about the intriguing complexities of the human body, as well as keep an eye out for these often lesser-known conditions.

Here are some of the oddest medical cases that we covered in 2023.

Related: 10 bizarre medical case reports from 2022

1. Scuba dive triggers deadly blood syndrome

After scuba diving deep into an underwater cave, a man developed a deadly blood syndrome that caused fluid to leak out of his blood vessels. Doctors quickly recognized that the man had an extremely rare complication of decompression sickness, known as systemic capillary leak syndrome, and were able to give him prompt, life-saving treatment.

2. Rustling spider found in woman's ear

A woman in Taiwan got a nasty surprise when doctors discovered a 0.1-inch-long (0.25 centimeter) spider crawling in her left ear, alongside its hard, molted outer shell. For four days, she'd been hearing weird clicking and rustling noises coming from her ear — but she probably didn't suspect a hairy arachnid would be responsible for the disturbing sounds.

3. Man's tongue sprouts thick, green 'fur'

A moss-like growth developed on a man's tongue. The condition, appropriately known as hairy tongue, is caused by an overgrowth of the bumps on the tongue that are normally shed when they come into contact with rough objects, such as a toothbrush or solid, textured foods. About 13% of people experience hairy tongue at some point in their lives, and the hairs can be any color, depending on the types of food and bacteria that get trapped in them.

4. New species of bacteria identified after stray cat bite

Scientists discovered a new species of bacteria after a man was bitten multiple times by a stray cat. His hands and forearms turned red and swelled up, but the man fully recovered after a five-day course of antibiotics. In the lab, scientists determined that he'd been infected by a type of Globicatella bacteria, a small microbe that resembles Streptoccocus bacteria, best known for causing strep throat and scarlet fever.

 5. Fetus removed from 1-year-old's brain

Doctors surgically removed a fetus from a 1-year-old's brain in an extremely rare medical case. The fetus was the child's monochorionic diamniotic twin, meaning it had come from the same fertilized egg as the child and also shared the same placenta, but it had developed in a separate amniotic sac. During pregnancy, one fetus was enveloped by the other and died as a result, but its remnants remained in the remaining child's head even after birth.

6. Knife blade 'floats' to other side of man's belly

Doctors stitched up a man's knife stab wound but forgot one important thing: the 5.9-inch (15 cm) blade was still stuck in his belly. A day later the blade had "wandered" to the other side of the man's body, but miraculously, it did so without damaging any of his surrounding organs.

7. Python parasite invades woman's brain

A woman in Australia was infected with a parasitic worm called Ophidascaris robertsi that normally lives in pythons and has never been known to infect humans before. Doctors pulled the 3.15-inch-long (8 cm) red worm, which was still alive and wriggling, out of her brain. It's thought that the woman accidentally consumed O. robertsi eggs either from directly eating contaminated leafy greens or indirectly via her soiled hands or kitchen equipment.

8. Toddler's brown eyes turned blue after taking COVID-19 drug

After taking an antiviral drug called favipiravir to treat COVID-19, a 6-month-old boy's dark-brown eyes suddenly turned indigo blue. This shocking color change was believed to be a side effect of how the body processes the drug. The boy's eyes returned to their usual color after treatment was stopped. However, doctors said the potential long-term effects tied to this temporary change in eye color are still unknown.

9. Tooth extraction causes man's brain to bleed 

A man's trip to the dentist had to be followed by a visit to the emergency department after a tooth extraction indirectly triggered bleeding in his brain. Doctors theorize the bleeding was caused by a sudden increase in blood pressure after the man's procedure. In addition, the patient had an undiagnosed genetic condition that reduces the flow of blood through the brain, which could have contributed.

10. Painful rash from eating undercooked mushrooms

A man developed a painful, itchy rash all over his back after eating undercooked shiitake mushrooms. The rash, which appeared streaky and red as if the man had been whipped, was caused by an overblown inflammatory reaction to a carbohydrate called lentinan. The carb is normally broken down at high temperatures during cooking, but raw and undercooked shiitake mushrooms contain enough to trigger a reaction.

Ever wonder why some people build muscle more easily than others or why freckles come out in the sun? Send us your questions about how the human body works to community@livescience.com with the subject line "Health Desk Q," and you may see your question answered on the website!

Tarantulas are hair-covered beasties. But most spiders don't have such "furry" bodies. So why do tarantulas look so hairy? 

These hairs are more important than you might think.

"Unlike the very limited functions of human hairs, hairs on tarantulas (and other spiders) can do so very many different things," Jerome Rovner, former associate editor of the Journal of Arachnology by the American Arachnological Society, told Live Science in an email.

Sensing the world

Tarantulas are hairy for several reasons. Unlike mammal hair, which is made of keratin, tarantulas' hairs, called setae, are made of chitin, a derivative of glucose that also makes up the structure of a spider's exoskeleton. 

Some of these hairs act as sensory organs, helping tarantulas smell, taste, touch and detect vibrations from the world around them. These sensory hairs are found mainly on the spiders' legs and mouthparts and feed into sensory nerves located in the spider's "skin" or cuticle..

The most sensitive hairs, called trichobothria, detect even the smallest changes in air movement because of their "ball and socket" attachment to the membrane in the cuticle. These hairs help guide tarantulas in capturing or responding to escaping prey. In 1883, German zoologist Friedrich Dahl named these "hearing hairs" when he observed that they moved to the sound of a violin.

The chemically sensitive hairs used for smell and taste are blunt and hollow. They also play a role in reproduction and help the tarantula look for a mate. "Male tarantulas wander in search of a female's burrow. If they walk near such a burrow, their contact chemosensitive hairs are stimulated by the sex pheromone that is bound to silk lines near the burrow's entrance, thereby enabling the male to find the female," Rovner explained, adding that these hairs could possibly detect chemicals left by  nearby prey.

 Related: Why do spiders have 8 legs?

Tarantula hairs serve three other functions. First, they help tarantulas, which are cold-blooded, regulate their body temperature. 

"The hairs trap a layer of air against their body and appendage cuticle, creating a kind of insulation," Rovner said. "With a thick coat of hair, tarantulas can remain active throughout cool nights in tropical rainforests and deserts." 

The long hair also serves as a sort of waterproof coat that can "repel water if the tarantula is submerged by flooding," Rovner said. 

Finally, the undersurface of their leg hairs are "sticky." This helps tarantulas climb smooth vertical surfaces. These dense networks of bristles are called scopulae and also help with capturing prey.

Many tarantulas in the Western Hemisphere also have up to 1 million deadly sharp hairs on their abdomen that they use for defense. These barbed, or urticating hairs t "can embed in the skin, eyes, and mucosal membranes of predators, causing irritation," Rovner said. 

When threatened, tarantulas use their hind legs and rub against their abdomen to detach these urticating hairs, creating a mist of stinging spines that penetrate the predator so they can escape. 

When people are hit by urticating hairs, they can cause redness, stinging and itching —and even blindness if they strike the eyes. 

Tarantulas native to the Eastern Hemisphere, by contrast,  do not have urticating setae. Instead they have more potent venom and use an aggressive stance to warn predators before they bite.

A strange, yellow, spider-like creature with four near-black eyes and large bulbous claws has been pulled from the depths of the ocean off Antarctica.

The never-before-seen animal is a sea spider — a distant relative of horseshoe crabs and arachnids that live on the ocean floor, eat through a straw-like proboscis instead of a mouth and breathe through their legs.Scientists have discovered more than 1,000 species of sea spiders all over the world.

The newfound species, Austropallene halanychi, was pulled from the ocean floor in the Ross Sea, about 1,870 feet (570 meters) below the surface. In addition to all the other weird things about sea spiders, the new species has large claws that look like "boxing gloves," which it likely uses to grab hold of soft foods like anemones and worms, study co-author Andrew Mahon, a biologist at Central Michigan University, told Live Science. The study was published Nov. 28 in the journal ZooKeys.

A. halanychi's body is about 0.4 inches (1 centimeter) long, but its legs stretch nearly 1.2 inches (3 cm) long. That gives the species the spindly look typical of many sea spiders — though some species can grow much larger, reaching nearly 2 feet (60 cm) wide.

Related: Sea spiders can regrow their anuses, scientists discover

What's more, this new species is likely just a drop in the bucket when it comes to the undiscovered wildlife living at the bottom of the Southern Ocean — an ecosystem home to everything from brightly colored sea stars and otherworldly marine worms to sponges and cold-water coral.

"The benthic environment in Antarctica is an area of science that we need to keep exploring," Mahon said. "There's so much down there that every time we go, we find new things."

To learn more about this environment, researchers drop nets deep underwater to pick up whatever might be hanging around at the bottom. After pulling the nets up, they sort everything they caught and preserve each specimen before shipping them back to labs for further analysis.

But with so many potentially new species to describe, it can take time to go through all the samples. A. halanychi was first pulled up in 2013 by the Nathaniel B. Palmer, a U.S. research vessel. Recently, Mahon and his colleague Jessica Zehnpfennig took it out of storage and identified it as a species new to science by analyzing its body shape and genetics.

Yet researchers may also be running out of time to study the Antarctic seafloor. As the climate keeps changing, warmer waters may threaten the future of some of the species living in this isolated and unique ecosystem, Mahon said. One of the reasons that researchers keep studying the Antarctic seafloor, he said, is to help describe and protect this biodiversity before it’s too late.

Certain male spiders in South America usually give their partners a tasty snack before mating. But in stressful environmental conditions, males may "cheat" in their mating ritual by offering females a useless ball of silk instead of a nutritious meal, a new study has found.

The research shows how spiders may adapt their behavior to reflect changes in their environment.

When a male Paratrechalea ornata spider wants to mate, he'll snag an insect and prepare it for a female, said study co-author Maria Albo, a biologist at the University of the Republic in Uruguay.

Related: Female spiders play dead during sex so males don't have to worry about being eaten

The spider starts by wrapping the insect in silk over and over until it forms a nice, little ball with a juicy treat hidden inside. "And then they start to walk along the river, along the stones," Albo told Live Science.

If a female takes the bait, she'll grab onto the gift with her mouth and slowly digest the silk to reach the food inside. While that's happening, the male mounts the female and they mate.

But some P. ornata males try to mate without going through the hassle of giving a gift. Instead of packaging a piece of food, these males will wrap up something not so tasty, like a leaf or even the leftover bits of an insect they've already eaten.

Albo knew that some males offered "worthless" gifts, but in the new study, published July 27 in the journal BMC Biology, she and her colleagues compared the prevalence of worthless-gift giving in two distinct habitats in Uruguay. One, in southern Uruguay, has a relatively stable climate. The more northern habitat is more affected by El Niño and is a more variable and unpredictable — and, therefore, more stressful — climate for a spider. In addition, the southern habitat had vastly more prey than the northern one did.

The team collected spiders along the river and checked what was inside their silk balls. In the less-stressful, southern population, males carried worthless gifts just 38% of the time. But in the more-stressful, northern population, males had worthless gifts a whopping 96% of the time.

Albo offered a couple of theories that might explain this discrepancy. For one, spiders in the stressful habitat might have to be more focused on survival, because the amount of nearby food is lower. So, the stressed-out males may be more tempted to keep the food to themselves instead of giving it away to females.

In addition, spiders in the stressful habitat were smaller, perhaps as a result of having less food around. So smaller-bodied females may not need any extra food to stay healthy. But larger females in the less-stressful habitat may need the extra food the males provide to produce healthy offspring.

These kinds of gifts given before mating, known as "nuptial gifts," occur in many different animals. In many scorpionfly species, males offer females either a dead insect or a ball of saliva to eat while they mate. Male great gray shrikes (Lanius excubitor) — a species of small, carnivorous bird — often offer their potential mates a dead mouse or lizard. And katydids have combined mating and feeding — as they copulate, the males will also provide the females with a "spermatophylax," a gelatinous ball of nutrients that the females will eat after they've finished mating.

Two new species of blind and colorless daddy longlegs spider have been discovered — one in the dry western region of Australia, and one on the lush tropical island of Réunion.

Both of the species live in underground habitats, which likely led to their colorless bodies and blindness. And researchers believe that both of these subterranean spiders could tell us an interesting story about the way species evolve and move over time.

This study "really highlights why it is that biodiversity discovery matters and how it is that you can find really unusual species in some of the strangest places that you look," Prashant Sharma, a biologist at the University of Wisconsin-Madison who was not involved in the new research, told Live Science.

Spiders in the Pholcidae family are found all over the world and are notable for their long, spindly legs,  which earned them the common nickname "daddy longlegs." Because they tend to live in dark places, such as basements, they're also often called "cellar spiders." The researchers published descriptions of these two new Pholcid species on July 24 in the journal Subterranean Biology.

Related: Are daddy longlegs really the venomous spiders in the world?

These daddy longleg spiders should not be confused with harvestmen, another type of arachnid often referred to as daddy longlegs. Unlike these Pholcid spiders, which look like regular spiders with two distinct body sections, harvestmen often look like they have a single, round body section hoisted aloft by their wire-thin legs.

The first new Pholcid spider was discovered in mining boreholes of the Pilabra, a dry and rocky habitat in a remote corner of Western Australia. The species belongs to the genus Belisana, which — prior to this study — was thought to only live hundreds of miles away, in Asia and the more vegetated northeast region of Australia.

Because this spider lives so far away from other members of its genus, the researchers think that Belisana spiders may have once been much more widespread in Australia. They speculate that the genus may have lived all across the continent about 60 million years ago, when it was covered by forests. But as western and central Australia grew drier, many of the Belisana spiders living there could have died out — except for this newfound species, Belisana coblynau, which had by then adapted to live in underground environments that hadn't changed as drastically as the surface ecosystem.

The other new species described in the paper was also found underground, but this time in a lava tube — a tunnel formed by molten lava — on Réunion, a French island off the coast of Madagascar in the Indian Ocean.

This spider is in the genus Buitinga, with its closest relatives living on the African mainland. But no Buitinga spiders are known to live on Madagascar, despite the fact that Madagascar is closer to the African mainland and much larger than Réunion. Complicating the mystery, daddy longleg spiders don't "balloon," a process in which baby spiders weave parachutes out of silk to let the wind blow them around — and a great way to travel from island to island.

Because of this, the researchers speculate that these Réunion Buitinga spiders likely ended up on the island due to a single, one-off event, like a log carrying a group of spiders across the sea or a storm carrying the spiders off the mainland in hearty gusts of wind.

Cave-dwelling animal species, including spiders, often lose their eyesight and their color as they adapt to underground habitats, Sharma said. Maintaining eyesight and producing body pigmentation requires a lot of energy, he added, and in a dark environment where there's little or no light, like a lava tube or a mining borehole, animals are often better suited putting their energy elsewhere.

For example, some animals that live underground evolve a keen sense of smell, Sharma said, which can help them get a sense of what’s happening in the dark around them.

Throughout history, tales of giant spiders have gripped the human imagination — from Arachne, the half-woman, half-spider figure in Greek mythology to J'ba Fofi, the rumored monkey-size spider of the Congolese rainforest and Shelob, the monstrous arachnid who keeps Frodo the hobbit on his toes in "The Lord of the Rings." 

But are there real-life spiders that inspired these stories and myths? What, in fact, is the biggest spider in the world?

While none are quite as enormous as those fictional beasts, the real world contains giant spiders galore. Just take giant huntsman spiders (Heteropoda maxima), which are the world's largest spiders by leg span. Measuring 11.8 inches (30 centimeters) across, these arachnids can reach the size of a dinner plate. 

But another spider species is so large it's closer to the size of a puppy. "If we're talking about the largest species of tarantula, that would be a species called Theraphosa blondi," said Ray Hale, a wildlife lecturer, arachnologist and vice chairman of the British Tarantula Society. "That is, the goliath bird-eating spider."

Related: What is the deadliest spider in the world?

How big is it?

Most spiders can be split into two broad groups, Hale told Live Science: araneomorphs (also known as 'true spiders', a group that includes 90% of spiders on earth) and mygalomorphs. Tarantulas are mygalomorphs, a group that's considered more primitive than true spiders. This means that they have evolved less since ancient times, and have therefore maintained certain features that true spiders have since shed — such as downward-pointed fangs, and their large size. 

This is why tarantulas feature the biggest spiders on Earth, including the West African Hercules baboon spiders (Hysterocrates hercules) — hefty creatures whose legs stretch to about 8 inches (20 cm); and face-size tarantulas Poecilotheria rajaei, which can also reach 8 inches in diameter and are native to Sri Lanka. Even larger are Brazilian salmon pink bird-eaters (Lasiodora parahybana), whose legs can reach 11 inches (28 cm).

But none of these beat goliath bird-eaters, which live in dense rainforest in northern South America. While these spiders have slightly shorter legs than their huntsman cousins, stretching to 11 inches — their weight gives them the edge. 

At 6.17 ounces (175 grams), and with bodies measuring 5.1 inches (13 cm), they are double the weight of their salmon pink relatives, making them the largest spiders in the world by mass. In 2014, an entomologist roaming the jungles of Guyana came across a goliath birdeater that was so big, it rustled the undergrowth and was equivalent in size to a young puppy — though a bit less cuddly, perhaps.

What does it eat?

The goliath bird-eater's name is a bit of a misnomer. "Yes, it is a big spider. Does it eat birds? Not really," said Hale. There are different theories on where the name came from. It was possibly inspired by a 19th-century engraving that showed these arachnids feasting on birds, while Hale said the name came from the accounts of 16th-century explorers to South America who put two-and-two together when they discovered some chicks that had fallen into the silk-lined burrows of this ground-nesting tarantula. 

But Hale noted that while the nocturnal hunters might opportunistically pounce on vulnerable birds — and the occasional mouse — the bulk of their diet is made up of crickets, lizards and frogs. The spiders are near-blind, so they use extremely delicate bristles on their legs and abdomen to sense slight vibrations that guide them to their food. Their prey meet the sharp end of the tarantulas' 1 inch-long (2.5 cm) fangs, which inject a lethal amount of neurotoxic venom, followed by digestive juices that liquefy prey's tissues so that the spiders can slurp it up. 

Goliath bird-eaters have their own predators, including snakes, wasps and humans — who report that the spiders have a delicious prawn-like flavor when roasted in banana leaves. 

Is this spider harmful to humans?

Goliath bird-eaters are more likely to scurry away from a human than attack. And while there's nothing nice about receiving a nip from their needle-like fangs — an experience that's been compared to a wasp sting — their venom isn't potent enough to harm us. "You're not going to die from it. They're not dangerous," Hale said. 

They do, however, have a secret weapon to ward off unwanted attention: By rubbing their hind legs against their abdomens, they release a flurry of hook-shaped bristles called "urticating hairs" that, once airborne, can become lodged in the skin and eyes and cause enough irritation to drive a predator away. That only happens after these spiders have delivered a warning: Threatened tarantulas will rub their front legs together to produce a high-pitched hissing sound that warns uninvited animals away. Called "stridulation," it's loud enough to be heard from up to 15 feet (4.6 meters) away.

And if that's not enough, these spiders can live for an extraordinarily long time. Along with their huge size, female goliath bird-eaters can live for up to 25 years, Hale said. Alongside the other wonders of their biology, this strikingly long lifespan is perhaps another reason that these behemoths deserve our respect and admiration, more than our fear.

There seems to be no ideal number of legs. Humans have two, dogs have four, insects have six and millipedes can have over 1,000. So what made spiders settle for eight legs? 

"I think the best answer and the simplest answer is that spiders have eight legs because their parents did," Thomas Hegna, an assistant professor of invertebrate paleontology at the State University of New York at Fredonia, told Live Science. "But then that gets into sort of a regress, and somewhere this all had to start."

If we follow the succession of eight-legged spider parents back to about 500 million years ago, during the middle Cambrian Period, we arrive at the root of the chelicerate lineage, the group of arthropods that contains spiders. If we go even further back, to 541 million years ago, we find the ocean-dwelling lobopods, the ancestors of all arthropods. 

The name "lobopod" doesn't refer to a single species but rather a large variety of species with rather simple bodies. Basically, they were wormlike creatures with segmented bodies. Each segment featured roughly identical pairs of short, stubby legs, and this pattern continued along the lengths of their bodies. 

Related: What is the deadliest spider in the world?

As the lobopods evolved, they began specializing their legs and fusing body segments. The early chelicerates seem to have fused their small body segments into two big ones: the head and the abdomen. Scientists aren't sure why, but the head kept the legs, and the abdomen lost them. By the time spiders appeared 315 million years ago, they inherited a body plan that was likely already 150 million years old.

It's unclear which environmental pressures, if any, caused chelicerates to settle on their eight-legged arrangement. However, we know a great deal about where their legs came from — and it's weird.

"Those legs are actually part of their mouth," Nipam Patel, a developmental biologist and director of the Marine Biological Laboratory, which is affiliated with the University of Chicago, told Live Science. 

Because spiders, insects, crustaceans and millipedes all evolved from an ancestor that likely had a segmented body with a set of appendages on each segment, these species are just highly modified riffs on that basic plan. According to Patel, all arthropod appendages — including legs, antennae and even mandibles (the jaws) — can be traced back to a stubby lobopod appendage. 

Take a mantis shrimp. It swims with a bunch of little legs on a segmented abdomen. On the cephalothorax (a fused head and thorax) are its walking legs, and then near its mouth are little appendages that not only make up its jaws but also sweep food into its mouth to help it eat. 

Compare that to an insect, whose abdomen doesn't have appendages. But it has six legs on its thorax, while its head and mouth are basically set up like the mantis shrimp's.

Then, there are spiders.

"If you look at a spider embryo, it looks exactly like an insect embryo," Patel said. "Except it only grows the legs on its head. But instead of using those as mouthparts, it uses them to walk."

The reason spiders walk with appendages from their faces goes back to lobopods and the original chelicerate body plan. While modern arthropods are spoiled for specialized appendages, the lobopods were wormlike creatures with many sets of roughly similar appendages. 

Related: What is the largest arachnid to ever live? 

"Initially, all of the legs were the same," Heather Bruce, a research associate at the Marine Biological Laboratory, told Live Science. "But then the first appendages became differentiated for being a sensory appendage, like for sensing and grabbing food."

From that point, the spider's chelicerate ancestors began to diverge from the other groups. In the ancestors of insects and crustaceans, the lobopod's multitasking front appendages lost their grabbing and feeding ability and became specialized sensory structures called antennae. But for chelicerates, those same appendages lost their sensory capabilities and became fangs. 

Meanwhile, chelicerates' second leg pair evolved into a set of grabby appendages called pedipalps; the following four sets of legs remained in their role as walking legs, and all appendages after that were lost. 

Well, not all of them. "Spinnerets evolved from spider legs," Bruce said. "There are really cool fossils in amber of a species that looks to be an ancestor of both spiders and scorpions, so it has some intermediate traits between the two. And on that fossil, there are very clear legs hanging off of the abdomen."

Spiders are common critters. And, as almost all of Earth's 43,000 known spider species are venomous, it is likely that most people have encountered a venomous spider at one point or another. 

So that's the bad news. The good news, however, is that of these, only 25 species are known to have killed or caused serious harm to humans. But which spider is the deadliest?

The deadliest spiders — or at least those most frequently cited as having caused death or serious injury to humans — are funnel-web spiders (Atrax), redback and black widow spiders (Latrodectus), banana and wandering spiders (Phoneutria) and recluse spiders (Loxosceles). 

But even these deadly spiders, with potent venom and fangs primed for piercing skin, are not particularly dangerous to humans. The American Association of Poison Control Centers (AAPCC) tracked only one death caused by a spider bite in the U.S. in 2021. Australia, home to some of the most venomous spiders in the world, hasn't reported a single spider bite death since the 1980s. 

"It is incredibly rare to have a deadly spider encounter," said Rick Vetter, a retired research associate with the Department of Entomology at University of California, Riverside, whose research focused on medically important spiders. "Considering all the bad things that could happen to you, if spiders are your biggest concern, then you are living the good life."

Related: Are daddy longlegs really the most venomous spiders in the world?

Funnel-web spiders top the list of deadliest spiders, if only for their storied venom. Native to Australia, these spiders boast venom that's so potent their bite can kill within minutes. "The deadliest is probably the funnel-web spider and its relatives. The Sydney funnel web spider (Atrax robustus) can kill a toddler in about 5 minutes and a 5-year-old in about 2 hours," Vetter told Live Science. Although no one has died from these spiders since the advent of antivenom in the 1980s, it is difficult to imagine a toddler receiving treatment soon enough to recover from a funnel-web bite.

Phoneutria spiders, the most common of which are often referred to as banana spiders or wandering spiders, are native to Brazil and have the most neurologically active venom of any spider. But they rank a bit lower on the list of the world's deadliest spiders because their venom works relatively slowly, leaving ample time for treatment. And Loxosceles spiders, the most familiar of which is the brown recluse (L. reclusa) found in the U.S., may be one the most common causes of spider-related injuries, with painful bites that can cause body aches and fever and take months to fully resolve. But they are very rarely deadly. 

The only arachnid genus that gives the funnel-web a real run for its money as the deadliest spider is Latrodectus, which includes the Australian redback (Latrodectus hasselti) and the more familiar black widow spider in the U.S. These spiders have a slight edge because they bite humans more frequently than funnel-web spiders, with comparably potent venom. "The most venomous species (Sydney funnel-web spiders, Brazilian wandering spiders) don't kill or impact that many people," Linda Rayor, a behavioral ecologist at Cornell University who focuses on spiders, told Live Science in an email. "It is the more widely-distributed black widows that are going to be the stars of your story."

It's important to note that, while AAPCC's annual reports carve out a section for spider bite statistics, it isn't easy to get a real handle on spider bite mortality or morbidity. 

"A number of human deaths each year are attributed to spiders," Rod Crawford, curator of arachnids at the Burke Museum at the University of Washington in Seattle, told Live Science in an email. "However, from a scientific viewpoint, almost none of these attributions are evidence-based." 

Related: 11 deadliest spiders

It is exceedingly rare, Crawford explained, for a victim to see a spider on their skin, feel a bite, capture that same spider, and then bring the offending spider to a physician (let alone a spider specialist) for analysis. "Practically all of the 'spider bites' you hear about, including those reported to poison centers originate from the belief that if you didn't see what bit you, it was a spider," Crawford said. 

Rayor echoed this sentiment. "I have spent a surprising amount of time trying to track down the human mortality rate from spiders and it is miniscule," she said. "This isn't reliably reported, but it is clear that not that many people get killed by spiders."

Keeping in mind the flawed nature of spider bite statistics, The Australian Museum claims that about 2,000 people are bitten by redback spiders each year, and that the antivenom to treat funnel-web spider bites has been given to about 100 patients since 1980. AAPCC's annual report tracked about 3,500 spider bites in the U.S. in 2021, with about 40 "major" clinical outcomes. Nine of those serious outcomes were attributed to black widows; 29 major outcomes and the only death that year were attributed to brown recluses. There were no spider bite deaths in AAPCC's 2020 report, which tracked seven "major" black widow bites and 23 "major" brown recluse bites.

This means that the deadliest spiders are, in fact, not very deadly. "True human spider bites of any kind — dangerous or harmless — are vanishingly rare," Crawford said. "Take me as an example: Over a long career I have handled tens of thousands of live spiders with my bare hands. Only 3 actual bites resulted; none of the 3 had any significant effect. So when people tell me spiders crawl into their beds at night and bite them while they are asleep, I just roll my eyes."

Vetter agreed. "In reality, spiders are way down the list of things to be concerned about."

Spiders have a keen sense of sight, but once they begin to starve they also start to go blind.

Biologists made the startling discovery while studying the eyes of bold jumping spiders (Phidippus audax) in the lab. They found that when they decreased the diets of these tiny hunters, the spiders' vision decreased too, according to a study published in the May issue of the journal Vision Research.

"We started looking at their eyes and noticed dark spots that suggested degeneration," study co-author Elke Buschbeck, a professor in the department of biological sciences at the University of Cincinnati, told Live Science. "We were really surprised and not expecting that."

Jumping spiders have high-resolution color vision, which they see with their principal, forward-facing eyes. (They also have side eyes for black-and-white vision.) Buschbeck thinks that studying these spiders could provide insight into the role nutrition plays in human eye diseases such as macular degeneration.

The spiders’ degenerating eyesight was initially spotted by one of Buschbeck’s undergraduate students, Miranda Brafford, who was examining the eyes of several of the wild-caught spiders using the lab's custom-built ophthalmoscope — a device designed to take fluorescent images of the retinas of animals with teensy eyes, such as spiders and insects. Brafford, who is a co-author of the study, noticed that some of the spiders had developed spots on their photoreceptors, which are cells that convert light into signals that are sent from the eyes to the brain. The spots suggested that the spiders' eyesight had degenerated. They then used electron microscopy to examine thin cross sections of the photoreceptors to confirm that the cells were indeed dying, according to an April 20 statement.

Related: Female spiders play dead during sex so males don't have to worry about being eaten

To test their theory that poor nutrition was the culprit, the team divided the spiders into two groups: One was fed a normal diet of crickets and bee pollen while the other received half portions.

"The condition of the eyes of the spiders with less nutrition was much worse," Buschbeck said. "We could tell just by looking at them with the ophthalmoscope that some of their photoreceptors had died." 

The researchers think that this shift in vision could be because photoreceptors require a lot of energy in the form of nutrients to function optimally, and if they don't receive a sufficient energy supply "the system fails," according to the statement.

While humans aren't spiders, "the photoreceptor mechanism is very similar" between the two species. So something similar could be at play in people with macular degeneration, though more research would be needed to show that, Buschbeck said.

"In both cases, it has something to do with energy metabolism and those photoreceptor cells, which are extremely energetically costly," Buschbeck said. "It's not easy for an organism to keep up with their energy needs [when nutritionally deprived]."

Deadly spiders that can survive underwater for over 24 hours are turning up in people's swimming pools in Australia after parts of the country were hit by heavy rain and floods over the past week. 

These swimming pool interlopers include funnel-web spiders, which are members of the Araneida family, with around 40 known species. The Sydney funnel-web spider (Atrax robustus) is one of the most deadly spider species, with males being responsible for most fatalities, likely because it evolved more potent venom to protect itself while wandering around looking for females to mate with. While no deaths have been recorded since antivenom became available in the 1980s, if untreated a bite can kill a child in as little as 15 minutes. 

Heavy rain and thunderstorms have hit parts of New South Wales since March 23, with a severe weather warning still in place for northern parts of the state. Sam Herrmann, a reptile keeper from Australian Reptile Park, told 9news that the rain has set funnel-web spiders "on the move."

"They're often seeking shelter, so the lip under the pool creates a great environment for them to hide and stay dry," he said. "However, sometimes they can accidentally fall into the pool."

Related: 11 deadliest spiders

Dan Smith, from the southern Sydney suburb Engadine, spotted one of these deadly spiders in his pool in the same spot he had found a trapdoor spider just a few days earlier. 

"It was quite an awakening event," he told 9news. "It was very active, very fiery." 

Vasilios Basil Haddad, from Sydney, also found a "nasty" male funnel-web spider in his empty pool and posted a video of it to Facebook. 

Meanwhile Lynda Smith, who lives on the northern New South Wales coast, found four eastern mouse spiders (Missulena bradleyi) in her pool. This species is similar in appearance to funnel-web spiders, with bulbous heads, powerful jaws and a venom of similar potency to their better-known counterparts. According to 7NEWS, she posted a warning about the presence of spiders to Facebook. "Please always check your pools before jumping in especially after rain," she wrote, adding they are "not to be messed with."

Funnel-web and mouse spiders are able to survive underwater by trapping an air bubble to the hairs on their underside, Helen Smith, the arachnology collection manager at the Australian Museum, told 7NEWS. She said spiders breathe differently than humans do, so it takes them much longer to drown. Most spiders have a dual respiratory system made up of a trachea and an organ called a book lung, which consist of a series of plates stacked up that allow for the diffusion of oxygen. The trachea carries oxygen to the tissues, while book lungs oxygenate hemolymph — the spider equivalent of blood. 

"They can survive for several hours and sometimes a thoroughly dead-looking spider can suddenly twitch or come back to life slowly," she said, adding they can also bite underwater. "But to bite they need to grip onto something — so don't poke them."

Smith captured the funnel-web spider in his pool and contacted expert Scott Johnson, who offered to take it to the Australian Reptile Park, which has the facilities to milk it to make antivenom. 

Herrmann told 9news that if people find spiders in their pools, they should scoop them out with a net. "If you so happen to get bitten, seek medical attention immediately," he said.

Black widow spiders in the U.S. are being killed off by an unexpected rival: their invasive relatives, but the motivation behind the highly aggressive attacks is not yet clear, a new study finds. 

The perpetrators, brown widow spiders (Latrodectus geometricus), likely originated in Africa or South America but have since spread to every continent on Earth apart from Antarctica. Brown widows are from the same genus as black widows, of which there are five species, including three that are native to North America: southern black widows (Latrodectus mactans), western black widows (Latrodectus hesperus) and northern black widows (Latrodectus variolus). But unlike black widows, which can all inflict extremely painful and occasionally lethal bites on humans, brown widow bites rarely cause significant harm to people, likely because they inject less venom into their bites despite having venom that is "drop-for-drop" just as toxic, according to the Center for Invasive Species Research (CISR) at the University of California, Riverside. 

In the U.S., brown widow spiders were first spotted in 1935 in Florida, and have subsequently spread across the southern states and into California, according to CISR. Since the invasive species was introduced, southern and western black widow numbers have plummeted, particularly in Florida, where southern black widows have gone "locally extinct" in certain areas.

However, scientists are unsure exactly why this is happening: Other spider species have not been affected by the brown widow's arrival, and there does not appear to be any competition for resources that would force the two widow species to fight one another.

Related: False widow spider preys on baby bat in never-before-seen encounter

In a new study, published Monday (March 13) in the journal Annals of the Entomological Society of America, researchers put solitary brown widows into laboratory tanks with one of three individuals from another spider species — a southern black widow, a red house spider (Nesticodes rufipes) or a triangulate cobweb spider (Steatoda triangulosa), which all overlap with brown widows in the wild — to see how the brown widow reacted to cohabiting with each of the species. 

When paired with the non-widow spiders, the brown widows peacefully cohabited with their tankmates in 50% to 80% of the tests. The rest of the time, one spider would kill and eat the other, but there was little difference between which species would end up victorious.

But when adult brown widows were paired with adult black widows, the invasive species killed and consumed the black widows 40% of the time, the pair peacefully cohabitated together 30% of the time, and in the remaining trials the black widows ended up victorious — but only after defending themselves from an initial brown widow attack. However, when sub-adult individuals of both species were mixed, the brown widows killed and ate their counterparts 80% of the time. Overall, brown widows were six times more likely to kill black widows than the other two spider species. 

In separate experiments, the team also showed that brown widows produce more offspring than black widows and that those offspring begin to reach maturity faster than black widows. This could explain why sub-adult individuals were so adept at killing younger black widows, which in turn would explain why black widow populations are collapsing in areas where brown widows have invaded, the researchers wrote. However, the researchers were surprised at the stark behavioral differences between brown and black widows.

Related: 11 deadliest spiders

"Brown widows are boldly aggressive and will immediately investigate a neighbor and attack if there is no resistance from the neighbor," study co-author Deby Cassill, an ecologist at the University of South Florida (USF), said in a statement. "But the black widows are extremely shy, counterattacking only to defend themselves against an aggressive spider."

The researchers are unsure why the closely related species react so differently to one another and plan to study brown and black widows in other parts of the world, such as Africa, to see if the same trends apply.

"I would love to see if their [brown widows'] behavior and displacement of black widows is something that they have adapted here in North America, or if this behavior is something they exhibit naturally even in areas where they have coevolved with black widows for much longer periods of time," study lead author Louis Coticchio, a doctoral student of conservation biology at USF, said in the statement.

The brown recluse spider is the most common and widespread of the brown spiders, but it is usually found only in the South and Central United States. It is a small species, with a violin-shaped body that can grow up to 0.5 inches (1.2 centimeters) long. It's bite, however, can pack a powerful, venomous punch. 

Brown recluse bites can cause necrotic (rotting) skin lesions and lead to serious reactions or even death in some people, especially children, according to MedlinePlus, a service of the National Library of Medicine. 

But about 90% of brown recluse bites are not medically significant, and they "heal very nicely, often without medical intervention and treatment," Rick Vetter, a retired research associate of entomology at the University of California, Riverside, wrote on the university's entomology department's website. 

After seeking emergency help, people with less severe bites will usually see their wounds heal quickly after they clean it and apply the RICE method — rest, ice, compression and elevation — to the affected area, he said. 

Where do brown recluse spiders live?

Brown recluse spiders (Loxosceles reclusa) are native to a region comprising Kansas, Oklahoma, Texas, Louisiana, Arkansas, Missouri, Mississippi, Alabama and parts of Georgia, Tennessee, Kentucky, Ohio, Indiana, Illinois, Iowa and Nebraska, according to Vetter. If you do not live in those areas, "it is HIGHLY UNLIKELY that you have a recluse spider," according to Vetter. "It is POSSIBLE but incredibly unlikely."

Appearance: How to identify a brown recluse spider

The brown recluse is part of the Loxosceles genus of spiders. Members of this group have violin-shaped markings on the top of their cephalothorax (fused head and thorax, where the legs are attached) and may be informally referred to as fiddleback or violin spiders, according to Oklahoma State University.

The brown recluse's violin markings can vary in intensity depending on the age of the spider, with mature spiders typically having dark brown violin shapes. The neck of the violin shape points toward the spider's rear, or bulbous abdomen. However, the violin shape is easy to misinterpret, so it is best to look at the eyes when determining whether a spider is a brown recluse.

The recluse's eyes are one of its most distinctive physical characteristics. "They have six eyes, instead of eight like most spiders," entomologist Christy Bills, the entomology collections manager at the Natural History Museum of Utah, told Live Science. Other types of spiders have eight eyes arranged in rows of four. Recluses, however, have six equal-size eyes arranged in three pairs, called dyads, in a semicircle around the front of the cephalothorax.

Another distinguishing characteristic of the brown recluse spider is its uniformly colored abdomen (though the shade of brown varies from spider to spider) covered in fine hairs, which give it a velvety appearance. Their long, thin legs are also covered in fine hairs, not spines like some non-recluse spiders, Bills said. According to the Integrated Pest Management Program at The University of California, Berkeley, the genus name Loxosceles means "slanted legs," and refers to the fact that recluse spiders hold their legs in a slanting position when at rest.

The brown recluse's body (not including its legs) is typically between 0.25 and 0.5 inches (0.6 and 1.2 cm) long, according to Oklahoma State University.

In short, brown recluses have all five of these features, according to the Integrated Pest Management Program:

1. Six eyes in dyads (pairs)
2. Uniformly colored abdomen with fine hairs
3. No spines on the legs
4. Uniformly colored legs (no patterns, such as stripes or spots)
5. Body isn't more than 3/8-inch (1 cm) in length

Classification/taxonomy

According to the Integrated Taxonomic Information System (ITIS), the taxonomy of brown recluse spiders is:

• Kingdom: Animalia
• Subkingdom: Bilateria
• Infrakingdom: Protostomia
• Superphylum: Ecdysozoa
• Phylum: Arthropoda
• Subphylum: Chelicerata
• Class: Euchelicerata
• Subclass: Arachnida
• Order: Araneae
• Family: Sicariidae
• Genus & species: Loxosceles reclusa

Brown recluse behavior and mating

The brown recluse gets its name from its color and its "shy nature," Bills said. "Most spiders go out of their way to avoid humans, which makes sense, considering we are thousands of times larger than they are and don't have a great record of behaving politely toward them."

These primarily nocturnal spiders build webs that serve as shelters as well as trigger systems, alerting them when prey is passing nearby so they can actively hunt it down, according to the Integrated Pest Management Program. They typically eat insects, such as silverfish and crickets, according to Oklahoma State University. 

As dawn nears, brown recluses find dark, sheltered hiding places; in nature, they may find refuge in rock cracks and crevices, but if they're near humans, these spiders may camp out in places such as shoes or around human-altered environments, including trash cans, rubber tires or tarps, a quirk that can put them in close contact with people. Male brown recluse spiders may also cross humans' paths when they search for female mates.

This is why brown recluse spiders are considered "house spiders," according to the Integrated Pest Management Program. 

Brown recluse spiders get around by hitchhiking on furniture boxes and other items from infested structures, according to the Illinois Department of Public Health. These long-lived spiders, who live an average of 2 to 4 years in the wild and up to 7 years in laboratories, have remarkable survival skills, and can go for six to 12 months without eating. 

Egg laying season lasts from April to July, but a female brown recluse needs to mate only once to produce fertilized eggs throughout her life, and she can produce 150 or more spiderlings in a year and up to five egg sacs in her lifetime. Thus, a single female hitchhiking into a human-made structure is enough to establish an infestation — a fact that may compel people who are moving around or from recluse spider territory to check their belongings before they leave.

Examples of brown recluse spiders living with people

Brown recluse spiders tend to head indoors during the winter as they search for warmth and food. They are drawn to clutter, often being drawn to attics and basements, where items are left for long periods of time. According to the University of Missouri, they are attracted to boxes of papers and files, which have lots of crevices in for hiding. 

"They really are shy, thus the name recluse," Wizzie Brown, an entomologist at Texas A&M University, said in a statement. "They come out to hunt insects, even other spiders, at night, but otherwise they like hidden areas where they aren’t bothered."

She said any seasonal clothes that have been stored away should be shaken out or put in a dryer on a high heat before being worn. She also said shoes that have been sitting in a closet for a long period should be checked. 

Once established within a structure, brown recluses are often difficult to control. Though hundreds of brown recluses may be present in a house, they may not be easily observed because of their reclusive, nocturnal habits. Therefore, if you see one brown recluse spider, chances are there are more nearby.

Examples of brown recluse populations around human structures include the discovery of 52 spiders at a dilapidated homesite in Mississippi in the early 1970s and 44 caught in sticky traps under a couch in a Tennessee home in just 24 hours, according to the Integrated Pest Management Program. In a wild case, eight 13-year-olds collected about 60 brown recluse spiders from a pile of bricks (the children didn't realize the arachnids were brown recluse spiders) in Oklahoma, but none of the children were bitten.

Even wilder still, a family living in a 19th-century home in Kansas collected 2,055 brown recluse spiders during a six-month period in 2001, according to a study in the Journal of Medical Entomology. The family had lived in the house for about 10 years, and although they regularly found brown recluse spiders, they only had one instance of getting bitten — when one individual's finger turned red for several days and then healed. "In fact, on many evenings, this family collected more brown recluse spiders per hour in their home than the entire California human population has ever been able to find in the state," according to the Integrated Pest Management Program.

Even if there is an infestation, Brown said people should not be overly concerned about bites. "If there is a recurring problem with brown recluse spiders in a location, I could see the need for action." she said. "But I know of a house that has regular pest control and would catch hundreds of them, but no one had ever been bitten. They want to avoid an encounter with us as much as we want to avoid an encounter with them."

Brown recluse bites and symptoms

Like most spiders, the brown recluse typically only bites when disturbed — though it is possible to inadvertently threaten them. The Texas A&M AgriLife Extension Program reports that this may happen if a spider is caught in bedding or clothing.

If the venomous brown recluse bites you, you might not feel a thing, although some people remember feeling a sharp sting, according to MedlinePlus. Bites sometimes, but not always, become painful within a few hours. The reaction the bite causes may range from mild to severe, especially in children.

Related: 11 of the deadliest spiders

"People react differently to bites," Bills said. About 10% of brown recluse bites cause moderate or greater tissue damage and scarring, according to Vetter. But the vast majority of bites result in inflammation, can heal without medical intervention and do not leave scars.

For those with higher sensitivity levels, victims might develop a necrotic lesion that looks like a "dry, sinking bluish patch with irregular edges, a pale center and peripheral redness," Michael F. Potter, an extension entomologist at the University of Kentucky (UK) College of Agriculture, wrote for the UK Entomology Department. These bites often develop a central blister. If the venom begins to destroy surrounding tissue, the wound may expand several inches over the next few days or weeks. Sometimes, this necrotic ulcer can remain for several months and leave a deep scar, Potter wrote.

According to MedlinePlus, symptoms of a brown recluse bite may include itching, chills, fever, nausea, sweating and a general feeling of discomfort or sickness. More severe symptoms include coma, blood in urine, yellowing of the skin and the whites of the eyes (known as jaundice), kidney failure and seizures.

In rare cases, the bite can cause systemic loxoscelism, a severe illness that involves a blood clotting disorder and destruction of red blood cells, according to a 2017 study in the journal PLOS One. "Children are much more likely to develop this systemic syndrome," study senior author Dr. Jeremy Warner, a hematologist at Vanderbilt University, said in a statement. In severe cases, treatment requires hospitalization, blood transfusions and other supportive measures, he said.

Brown recluse bite treatment

There is no effective commercial antivenom approved for use in the United States. If you are bitten, MedlinePlus  recommends calling 911 or poison control (1-800-222-1222) or getting to an emergency room immediately.

The NIH says you should wash the area of the bite with soap and water, then wrap ice in a washcloth and place it on the bite area for 10 minutes. Remove the washcloth for 10 minutes, and repeat the process.

Then, go immediately to the emergency room and bring the spider, if possible, for identification purposes.

Brown recluse management

To decrease your odds of becoming an unwitting host to these six-eyed spiders, remove or reduce outdoor trash and unneeded outdoor structures, such as wood piles or boxes, especially those near the house, according to the Integrated Pest Management Program. You can also seal cracks around doors, electrical conduits and plumbing fixtures with caulk, expandable foam, weather stripping or other materials to prevent the spiders from entering the house.

If you're in brown recluse territory, move your bed away from the wall, remove bed skirts and clear away items stored under the bed. These moves will reduce the chances that a brown recluse will set up shop around your sleeping area and possibly bite you during the night. Moreover, don't leave clothes and shoes on the floor, or make sure to shake them out before putting them on. Store outdoor equipment, such as gardening gloves and baseball mitts, in tightly sealed bags or bins.

Sticky traps laid down on floor boards are a great non-chemical way to catch brown recluse spiders. Chemical control can be difficult, as these spiders can be challenging to find during the day. If used, liquid, aerosol and dust-based insecticides should be applied to cracks and other places where the spiders might be hiding, Potter wrote for the UK entomology department. But bug sprays are not effective against the brown recluse spider, as the long hairs on the bottom of their feet enable them to walk on treated surfaces without getting a lethal dose.

Brown recluse fangs are short and can't bite through clothing, so wearing long sleeves, pants and gloves can help protect you when you're working outdoors.

Originally published on Live Science on Nov. 14, 2014 and updated on March 5, 2024.

Additional resources

Watch "How to catch a spider" on YouTube that the University of California Statewide Integrated Pest Management Program produced.

Learn more about brown recluse spiders on the Missouri Department of Conservation website.

Read about ways to protect yourself from brown recluse spider bites from the Occupational Safety and Health Administration.

Bibliography

Medline Plus. National Library of Medicine. Brown recluse spider. Reviewed June 30, 2019.

Rick Vetter. How to Identify and Misidentify a Brown Recluse Spider. Updated January 2005.

Rick Vetter. Brown Recluse Spider Map

Oklahoma State University. Brown Recluse or Fiddleback Spider, Loxosceles reclusa 

Rick Vetter. Integrated Pest Management Program at The University of California, Berkeley. Brown Recluse and Other Recluse Spiders. Revised November 2018.

Integrated Taxonomic Information System - Report. Loxosceles reclusa. Generated Feb. 16, 2022.

Illinois Department of Public Health. Brown Recluse and Black Widow Spiders. 

Michael F. Potter. University of Kentucky College of Agriculture, Food and Environment. Brown Recluse Spider. Revised July 12, 2018.

Texas A&M AgriLife Extension. Field Guide to Common Texas Insects: Brown Recluse

Robinson, J.R. et al. PLOS One. "Defining the complex phenotype of severe systemic loxoscelism using a large electronic health record cohort" (2017)

Imagine a spider hanging from a silky thread, as still as a corpse, until its eight legs unexpectedly tremble. While this might sound like a horror movie, it's actually a nightly experience for jumping spiders (Evarcha arcuate) who can reach rapid eye movement (REM) sleep, the stage in which most dreaming occurs, a new study finds.

In the study, published Aug. 8 in the journal Proceedings of the National Academy of Sciences, researchers used cameras to examine jumping spiders while they slept, watching the motions of the arachnids’ eyes and bodies throughout the night. The twitching movements the team witnessed as the spiders snoozed was similar to that seen in humans and other mammals such as dogs, as well as nonavian reptiles and cephalopods during REM sleep.

The discovery came about unexpectedly for lead study author Daniela C. Rößler, a behavioral and evolutionary ecologist and postdoctoral fellow at the University of Konstanz in Germany. She was originally planning to study the arachnids' reactions to 3D-printed models of predatory spiders. But her research took a swift detour when she observed the spiders while they slept; at one point, she thought they were dead.

"They were all hanging from the lids of their boxes," Rößler told Scientific American. "I had no idea what happened."

Related: Dead spiders reanimated as creepy 'necrorobots'

With a "cheap night-vision camera" equipped with a magnifying lens she attached with duct tape, Rößler focused her lens on one of the females. At first, it simply hung there, immobile. But eventually, its legs began twitching, along with its abdomen and silk-producing spinnerets. At one point, its legs curled upward. The entire display lasted about a minute and "repeated periodically throughout the night," Scientific American reported.

"They were just uncontrollably twitching in a way that really looked a lot like when dogs or cats dream and have their little REM phases," Rößler told Scientific American.

For the study, Rößler and her team used an infrared camera to record 34 spiderlings (juvenile spiders). They witnessed "unmistakable eye-tube movements" that didn't occur at other times throughout the spiders' sleep cycles. According to the paper, jumping spiders have movable retinal tubes that help them redirect their gaze, and in spiderlings, these movements can be seen through their exoskeleton, which remains translucent during their youth.

The spiders' retinal movements occured at the same time as the leg curling and jerking, which are similar to limb movements seen in other animals experiencing REM sleep, according to a statement. And while the scientists couldn't easily observe retinal movements in adult jumping spiders, they did document similar leg movements happening at regular intervals during sleeping bouts.

Prior to this research, not much was known about the sleep patterns of spiders and other invertebrates, since the study of REM sleep is still largely focused on mammals and birds. However, scientists have already recorded similar actions in two other invertebrates: octopuses and cuttlefish, Live Science previously reported. 

While Rößler cautioned that it's too soon to say for certain that jumping spiders are dreaming, the evidence looks promising. To broaden her research, she and her team must conduct brain scans to prove that the spiders' brains are actually in a REM-like state. That's a tricky undertaking, considering that these tiny spiders, which measure about a quarter of an inch (6 millimeters) long, have brains the size of poppy seeds. To record the spiders' brain activity, scientists will need to insert an electrode into each spider's brain without crushing it.

Until then, scientists might find themselves dreaming about spider dreams.

"I personally think they are dreaming — just like any person watching a dog or cat sleep and kick their leg will think that they're dreaming — but being able to scientifically prove that is a whole different story," Rößler told The Harvard Gazette. "I don't think we can say they are, and I'm not even sure we will ever be able to say it, but the fact alone that we're thinking about it is already quite amazing."

Originally published on Live Science.

Taking a dead spider's lifeless body and reanimating it as a robot is an idea that would be the stuff of nightmares for most people. But scientists aren't most people. Recently, a team of researchers turned the corpses of wolf spiders into arcade-style claw machines that could pick up and move a variety of objects — including other dead wolf spiders.   

The idea for the mechanized arachnid grippers, or "necrobots," first came about when researchers noticed a dead spider curled up in a ball in a corner of their engineering lab. After looking up why the legs of dead spiders always seem to end up pulled tightly toward their abdomens, the scientists learned that spider joints were controlled through a hydraulic pressure system that fails when the arachnids die. The team then realized that they could reverse engineer this hydraulic system to hijack the spider's corpse and give it a second life as a machine.

By puffing air into wolf spider cadavers, the team found that all eight legs could be simultaneously straightened out and curled up again to create a grabbing motion that could then be used to lift up objects. Wolf spiders — a group that comprises nearly 2,400 species in the Lycosidae family — can carry objects much larger than themselves and have tiny hairs on their legs that give them extra grip. This means the necrobots could pick up a wide variety of objects, including delicate electrical components, irregularly shaped meshes and, yes, dead wolf spiders, the researchers explained in a new study. 

The researchers believe their work could inspire the creation of other necrobots from the corpses or individual body parts of other dead animals. "It's something that hasn't been used before, but it has a lot of potential," senior study author Daniel Preston, an assistant professor of mechanical engineering at Rice University in Houston, said in a statement.

Related: Millions of palm-sized, flying spiders could invade the East Coast, scientists say 

In humans and other vertebrates (animals with backbones), most joints are controlled by antagonistic muscle pairs, which are opposing muscles that pull a joint in different directions. An example of an antagonistic muscle pair in humans is the bicep and tricep: When the bicep contracts and the tricep relaxes, our arm bends at the elbow; when the tricep contracts and the bicep relaxes, our arm straightens out again. 

However, spiders only have a single flexor muscle in their joints that allows them to bend their legs. To straighten their legs again, spiders use a hydraulic pressure system, which involves forcing blood from a chamber near the thorax, known as the prosoma, into the legs. The blood acts as the antagonist to the single flexor muscle and pushes the joint back open. But when the spider dies, there is nothing to push against this muscle, and the joints close.

"When they die, they lose the ability to actively pressurize their bodies," lead study author Faye Yap, a doctoral candidate in mechanical engineering at Rice University, said in the statement. "That's why they curl up."

To transform the wolf spiders into necrobots, the researchers recreated the arachnid hydraulic system, substituting air for blood. The team inserted a needle into the prosoma of a dried-out spider corpse and superglued it in place. When they blew air into the chamber through the needle, the air flow activated the hydraulic system just as a spider's flowing blood would, forcing the legs to straighten. When the air was sucked back out through the needle, the legs returned to their naturally curled-up position.

Normally, spiders control each individual leg through valves that adjust the flow of blood into each limb. The researchers were worried about how this would affect the mobility of their reanimated spiders, as there was no easy way to open the corpses' leg valves. But it turned out that in dead spiders, the valves were permanently stuck in the "open" position, Preston said. This allowed the researchers to control all of a necrobot's legs simultaneously, making them perfect for grabbing objects, he added.

The dead wolf spiders were so well suited to their new task that the researchers were able to create a working necrobot on their first attempt. "We took the spider; we placed the needle in it not knowing what was going to happen," Yap said. "And when we did, it worked the first time, right off the bat." It is extremely rare for engineers to succeed so quickly when doing this type of trial-and-error experiment, she added. 

Further experiments with the necrobots showed that they could reliably lift objects that weighed more than 130% of their own body weight, and occasionally, they could lift even more. However, after around 1,000 cycles of opening and closing their legs, the necrobots became less efficient and showed signs of damage. 

"We think that's related to issues with dehydration of the joints," Preston said. However, the researchers think they can eventually overcome this problem by coating the legs with special polymers, which would extend the life span of the necrobots, he added.

The necrobots have a wide range of potential applications, according to the statement. The team has already shown that the spider grippers can be used to move fragile components in electrical circuits without damaging them, which hints at their usefulness for assisting in the assembly of microelectronics and other small-scale construction projects. And if the scientists can replicate their work with other species, that could further extend the range of projects that could benefit from a necrobot's delicate touch, the team reported in the study. 

Ecologists also could utilize necrobots to collect live insects to study from the wild without damaging them, Yap said. The reanimated spiders are likely to be highly effective tools for capturing insects because their legs have evolved specifically to catch tiny arthropods, and their natural camouflage could help keep them hidden in the field, she added.

Using necrobots instead of mechanical constructs made of metal and plastics  could also help to reduce the waste produced during tool manufacturing. "The spiders themselves are biodegradable," Preston said. "So we're not introducing a big waste stream, which can be a problem with more traditional components."

Wolf spiders are extremely common, widespread and easy to collect, so there would be a cheap and plentiful supply of spider corpses for engineers to transform into necrobots — as long as those engineers aren't arachnophobic, that is.

The study was published online July 25 in the journal Advanced Science.

Originally published on Live Science.

Male wolf spiders (Schizocosa stridulans) that improvise intricate dance moves are big winners in the mating game, wooing females with showstopping tap routines. Now, new research finds that the more complex the dance, the more likely the spiders are to find love. 

The study researchers found that improvised steps benefited the spiders, which live in humid, mostly forested areas worldwide. The ability to bust a complicated move wasn't associated with size or strength in males, but it may hint to females that the male possesses a certain athleticism and grace.

"Females aren't necessarily looking for the biggest male or the loudest male or the strongest male," study co-author Eileen Hebets, a biologist at the University of Nebraska–Lincoln (UNL), said in a statement. "But maybe they're looking for a male that is really athletic and can coordinate all of these different signals into one display."

Feel the noise

S. stridulans are brownish-gray spiders that can grow to be 1.4 inches (35 millimeters) in body length. But behind that drab coloration lies a flashy and flamboyant performer, with mating dances that involve males tapping their forelegs and vibrating their abdomens. Females feel these vibrations and decide whether or not to let the suitor get close enough to mate.

Recent UNL doctoral graduate Noori Choi, a student of Hebets', wondered what exactly the females found so intriguing about the mates that they eventually chose. He analyzed one of Hebets' experiments in which ready-to-mate female spiders were put in a soundproof chamber with one amorous male at a time. The researchers placed the spiders on top of thin filter paper, which easily transmits vibrations, and monitored them with cameras and a laser to detect every last shiver and twitch created by the male's dance.

Related: These male spiders use built-in leg catapults to escape sexual cannibalism

Out of 44 hopeful males, nine spiders were deemed acceptable by the female test subjects. The spiders that successfully mated also had the most complex dances, Choi found.

Getting into a groove

Choi analyzed the complexity of the spiders' dances with computer-science analyses that have been used to quantify the complexity of patterns in data signals, part of the process of data compression. These methods have never before been applied to arachnid vibrations. Previously, Hebets said, scientists looked at features of a spider's dance individually, focusing just on factors like vibration alone, or looked at very basic interactions, such as those between visual signals and vibrations. 

"Now we're at the point, with some really talented people who have quantitative skills, of coming up with computational ways to look at how all of these things might interact, and how the entire package might be important in ways that we would never understand if we were just looking at components A, B or C," Hebets said. 

Males danced with more complexity for heavier females, which are desirable mates because they're likely to be able to bear and take care of large broods of spiderlings, the researchers found. Successful males also amped up their dance complexity as the courtship went on — dances can last up to 45 minutes —which may have indicated that the females were communicating their interest in some way. 

"When you're talking about spiders," Hebets said, "I think that's something people don't tend to appreciate; that signalers are paying attention to the receivers, they're paying attention to their environment, and they're adjusting accordingly."

The complexity of these spiders' moves is the equivalent of a person dancing on a syncopated beat, changing up the tempo, or otherwise making unpredictable artistic choices. These moves didn't correlate with spider size or a male's ability to produce loud vibrations, the researchers reported May 18 in the journal Biology Letters. Instead, the important qualities seemed to be related to vigor and skill, the researchers said. 

Or maybe these males just stood out from the crowd by abandoning preplanned choreography and thinking on their feet.

"There are a lot of studies that show that animals prefer novelty, in some capacity," Hebets said. In the case of the lovelorn wolf spiders, "the males constantly changing things up" might be the best way to catch — and keep — females' attention, she added. 

Originally published on Live Science. 

The term "arachnids" likely conjures up visions of spiders: from creepy, crawly things silently spinning webs in the corner of the room to big, hairy creatures with fangs — the likes of the mythical Shelob or Aragog — stalking you in the dark. But just how big (and ferocious) can these arachnids get? Even better, what was the largest one to have ever lived?

Answering this question is deceptively simple. Arachnids are eight-legged arthropods, which means that this group not only contains spiders but also scorpions and ticks among other, much smaller and rarer groups. Of these, spiders are the most diverse group of arachnids (the 50,000th species was discovered recently, and that number is expected to grow). The problem is that exactly what counts as an arachnid is a bit of an open question.

Arachnids are part of a larger group of arthropods called the chelicerates. The chelicerates are subdivided into smaller groups, with arachnids being one group and horseshoe crabs (in the order Xiphosura) and sea scorpions (Eurypterida) being separate but related to the arachnids.

According to Russell Bicknell, a paleontologist at the University of New England in Australia, this is the traditionally accepted phylogeny. "But a paper came out recently that suggested this is wrong, and suggested that horseshoe crabs and sea scorpions are actually nested within arachnids."

Related: Why do Cambrian creatures look so weird? 

Thomas Hegna, an assistant professor of paleontology at the State University of New York (SUNY) at Fredonia, who was not involved in the new study, told Live Science in an email that the new phylogeny, which is based on molecular analysis, implies some groups of land chelicerates (spiders and scorpions) came before marine ones (horseshoe crabs and sea scorpions). However, despite the fact that this claim is well supported by genetic evidence, it is inconsistent with the fossil record. 

This might seem like paleontological pedantry, but it actually makes a huge difference when it comes to determining the largest-ever arachnid. 

According to the traditional view of the arachnid family tree (ignoring horseshoe crabs and sea scorpions), the largest living arachnid is likely to be a spider. 

There are two spiders that make great contenders for the title of "world's largest spider." The largest known spider by mass is the Goliath Birdeater (Theraphosa blondi), a 6-ounce (170 grams) spider whose body can reach up to 5 inches (12 centimeters) in length, a number that grows to 11 inches (28 cm) when its legs are included, according to the American Association for the Advancement of Science (AAAS). 

If one is to judge the size of a spider instead by the diameter of its leg span, then the largest spider may very well be the Giant huntsman spider (Heteropoda maxima), which has a leg span of about 1 foot (30 cm) in diameter, making it about the size of a dinner plate. Despite its size, this spider wasn't discovered until 2001. 

When we dive into the fossil record, we find that the largest-ever arachnid was likely not a spider, but a scorpion. Brontoscorpio anglicus was a scorpion that lived during the Silurian-Devonian era (between 350 million and 450 million years ago) and reached lengths of nearly 3 feet (1 m) long — five times longer than the longest scorpion alive today. However, the caveat here is that the one example of this species was described from a single fossilized finger, so the animal's actual size is an educated guess. 

Related: Is every spider web unique?

These animals are the largest-known arachnids, both living and extinct, as arachnids are traditionally defined. But if sea scorpions and horseshoe crabs are indeed considered arachnids, as new research might suggest, then the largest living arachnid is no longer a spider, but is instead a horseshoe crab.

The largest living species of horseshoe crab dramatically surpasses the largest living spiders. Tachypleus tridentatus, the largest of this group, can reach sizes of 31 inches (79.5 cm) and weigh as much as 9 pounds (4 kilograms), according to research published in 2017 in the Journal of Asia-Pacific Biodiversity.

As far as the largest-ever species goes, the title would likely go to a member of the now-extinct sea scorpions, a group scientifically known as eurypterids. Fossils suggest that many of these ancient marine predators would even rival humans in size. 

The largest species from this group was Jaekelopterus rhenaniae, a species discovered in 2007 that had claws up to 18 inches (46 cm) long. From the claws, researchers estimated that its body was roughly 8 feet (2.5 m) long, making it not only the largest potential arachnid, but the largest-ever member of the entire group that contains arachnids, the chelicerates. 

Originally published on Live Science.

For a type of orb-weaving spider, mating has a spectacular finale: The male catapults off a female's body at a speed too fast for a human to see with the naked eye. 

These amorous acrobatics aren't meant to impress the spiders' partners; rather, a male springs into action to escape the female's hungry mandibles, as sexual encounters for these arachnids would otherwise end with the male being eaten.

They leap for their lives by using a mechanism that has never been seen before in spiders, involving a joint in their front legs that enables them to launch their bodies dozens of centimeters in a split-second by storing kinetic energy and then suddenly releasing it, according to a new study.

Prior to mating, male spiders would secure themselves to the female's web with a silk "safety line," so that after catapulting they could climb back up to mate again. Males sometimes mated with the same female up to five times; and with the risk of being cannibalized looming in every encounter, post-sex catapulting likely evolved as a means of survival, the researchers reported.

Philoponella prominens spiders are tiny — males' bodies measure about 0.1 inches (3 millimeters) long, while females are about twice that size — and they live in colonies that can contain more than 200 spiders in a vast network of webs. When the study authors observed a colony of the orb-weavers in Wuhan, China, in 2019, they noticed that mating always ended with the males catapulting off the females so quickly "that common cameras could not record the details," said Shichang Zhang, lead author of the study and an associate professor at Hubei University's School of Live Sciences in Wuhan. That prompted the researchers to take a closer look at what was going on while the spiders were mating, Zhang told Live Science in an email.

Related: Weird and wonderful: 9 bizarre spiders 

But taking a closer look turned out to be exceptionally challenging. Because the spiders were so small and mating was over so rapidly (lasting only about 30 seconds from copulation to catapult), the study authors struggled to focus their high-speed camera's macro lens in time to film the mating act and its aftermath. In many cases, the males finished and sprang away before the camera lens was focused and ready.

"That's the most difficult part in this research," Zhang said.

The scientists collected around 600 P. prominens spiders and conducted 155 successful mating trials. In spite of the photography challenges posed by the speedy spiders, the researchers captured images with a camera shooting 1,500 frames per second, and then used software to measure the energy and speed of the male spiders' catapulting escapes. After the first mating, 97% of the males catapulted — and all of them survived. Males that failed to catapult "were captured, killed and consumed by the females," the study authors reported. When the scientists prevented 30 males from springing away by disrupting the catapult mechanism in the spiders' legs, all of those males were also devoured.

But when the spiders were able to fling themselves away, the stored energy in their legs propelled their tiny bodies at remarkable speeds: up to 2.9 feet per second (88 centimeters per second). That's the equivalent of an adult human taking a flying leap and landing one second later at a distance of nearly 1,740 feet (530 meters), Zhang said. 

"We hypothesized that the mechanism of the catapulting is that the legs are folded against the female, and then when released the hydraulic pressure causes the legs to rapidly expand," the scientists reported.

Similar mechanisms using hydraulic energy storage and release for rapid limb movement are found in other animals, such as the mantis shrimp's knockout punch and the blink-and-you'll-miss-it speedy snap of a trap-jaw ant's mandibles. "But they use the fast actions to either capture prey or escape predators," Zhang said. By comparison, the wee orb-weavers are the only known animals to use the technique as protection against sexual cannibalism, catapulting to safety so that they may live to mate another day. 

This could be a way for the males to signal their fitness as mates, as males that are physically superior to their competitors can perform multiple catapults while mating, "thereby increasing their chance of paternity," the study authors concluded.

The findings were published April 25 in the journal Current Biology.

Originally published on Live Science.

Pack hunting spiders exist in places other than your nightmares. While most spiders enjoy solitary lives, 20 of the roughly 50,000 known spider species live in colonies. One species, Anelosimus eximius, lives in extremely large colonies of up to 1,000 individual spiders that work together to build webs spanning several meters. When prey falls into their web, these social spiders coordinate and attack their victim together, which allows them to take down much larger prey than they could if they hunted alone. Until now, exactly how these spiders carry out such coordinated attacks was a mystery. 

It turns out, the spiders use vibrations in their mega-web to choreograph a synchronized swarming process, the study found.

"What is fantastic is that there is no leadership role among these spiders," said Raphael Jeanson, a researcher at the Research Center on Animal Cognition (CRCA)  at the University of Toulouse in France and senior author on a new study about the social arachnids. Rather, the entire spider colony coordinates its attack with each individual receiving the same information. 

Related: Creepy, crawly & incredible: Photos of spiders

As the colony attacks, the spiders descend on their prey by synchronizing two movement stages: closing in on their struggling victim and standing still. This allows the spiders to time their approach so that all of them strike at once. 

Using both field observations and computer simulations of this coordinated attack, Jeanson’s team learned that the attack is directed almost entirely by vibrations in the shared web. 

"When the prey falls in the web, this triggers the movement of the spiders," Jeanson told Live Science. "But after a while, they all stop for a few milliseconds before they start moving again."

By luring the spiders with a dead fly glued to the end of a vibration generator, the researchers showed that hunting behavior was, in fact, triggered by the struggling of helpless prey. However, that didn't explain the colony’s coordinated movements. 

For that, scientists needed a computer model. The models revealed that while the prey vibrations might trigger the initial movement, it was the vibrations made by the spider colony that enabled the predators to coordinate their attack. As each spider sensed vibrations from the prey, they started walking. But the steps of hundreds of spiders converging on a struggling insect also sent vibrations through the web’s fibers, and muddied the sounds of a trapped meal.

"It’s a bit like when you are in a room with people chatting," said Jeanson. To a spider, every step it takes makes noise. They then have to stop moving so they can listen for the prey, to make sure they are still heading in the right direction. 

The quieter the struggling prey is, the harder it can be for the spiders to coordinate their stop-and-go movements. When the researchers vibrated the web and then removed the lure, the colony responded by moving toward the prey, but then every spider had to stop moving to "listen" for telltale signs of squirming. If the prey was vibrating more intensely, the colony didn't need to be as quiet, so they were less synchronized, the scientists discovered 

This study was published March 7 in the journal Proceedings of the National Academy of Sciences.

Originally published on Live Science.

Wolf spiders are a family of mostly large, hairy and athletic arachnids. There are nearly 2,400 species of wolf spider that are found all over the world.

These spiders get their name from the way they hunt prey: Rather than spinning webs, these arachnids stalk prey like wolves do. Unlike wolves, however, wolf spiders don't hunt in packs; most are solitary creatures that hunt in the dark.

Wolf spiders are venomous, but their bites rarely cause people to become seriously ill.

And having these little arachnids around can be very beneficial. Because they eat insects like ants, bed bugs and cockroaches, they are considered a natural form of pest control around people's homes and gardens.

Fun facts about wolf spiders

• Wolf spiders have eight eyes: four little eyes and two pairs of bigger eyes above those. They use their amazing eyesight to hunt in the dark.
• Wolf spiders will bite you if they feel trapped, but their venom isn't deadly. Wolf spider bites can be painful.
• Brown wolf spiders can sometimes be confused for brown recluse spiders, which are extremely venomous and — in extreme cases — can result in seizures, kidney failure and death. If they're moving fast and out in the open, they're more likely to be wolf spiders. Brown recluses rarely venture out into open spaces.

Everything you need to know about wolf spiders

Wolf spider taxonomy

Here is the taxonomy, or classification, for the tardigrade, according to the Integrated Taxonomic Information System (ITIS):

Kingdom: Animalia

Phylum: Arthropoda

Class: Arachnida

Order: Araneae

Family: Lycosidae

Wolf spider pictures

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An invasive spider in the U.K. snagged two bats in its web, and only one bat survived the grisly encounter, thanks to the help of a local resident who freed the entangled creature before it met its doom.

The noble false widow spider (Steatoda nobilis) originally hails from the Madeira archipelago and Canary Islands in the North Atlantic Ocean, but the species is now found in other parts of Europe, as well as in Asia and the Americas. The black widow look-alike reached southern England in 1879 and has since spread toward Scotland and into Wales and Ireland, according to a statement. 

Prior to a new case report, published Feb. 21 in the journal Ecosphere, no spider in the Steatoda genus had ever been observed preying on bats — or any mammal, for that matter. But last July, Ben Waddams, a wildlife artist based in Shropshire, England, snapped photos of several bats trapped in a S. nobilis web at his home. 

Related: Ewwww! Photos of bat-eating spiders 

He shared the snapshots on social media, where they soon drew the attention of researchers at the National University of Ireland (NUI), Galway, Michel Dugon, head of the Venom Systems Lab at NUI Galway and senior author of the study, said in a video. "We actually understood very quickly that this was a first," Dugon said.

"We knew immediately the significance of Ben's discovery and contacted him to collaborate on documenting this in the scientific literature, as this furthers our understanding of this species capabilities as an invasive species," first author John Dunbar, an Irish Research Council postdoctoral fellow in the Venom Systems Lab, told Live Science in an email. 

Based on Waddams' photos, the team identified the spider as a mature female S. nobilis. The bats that fell victim to the spider's trap belonged to a colony living in Waddams' attic, according to the report. The spider had constructed its web directly beneath the entrance to the bat colony's roost, in an area spattered with bat droppings.

In July 2021, Waddams noticed a dead bat pup suspended in this opportunistically placed web, its wings tightly pinned against its silk-wrapped body. The posterior end of the young bat appeared purple and shriveled, suggesting that the spider had been feeding on the animal, the researchers observed. 

The venom of S. nobilis is a potent neurotoxin that carries some of the same toxins as the venom of true black widows (Latrodectus); past research found that the spiders use this venom to immobilize and feed on small vertebrates, including lizards, the authors noted in their report. 

"False widow spiders, just as their close relatives black widow spiders, have extraordinary prey capture techniques and remarkably potent venom, which allows them to capture small vertebrate prey many times larger than the spider itself with surprising ease," study co-author Aiste Vitkauskaite, a researcher at the Venom Systems Lab, said in the statement. 

"In addition to delivering a bite that injects potent neurotoxic venom, the noble false widow can use other strategies to assist in subduing prey," such as slinging sticky silk at them, Dunbar told Live Science in an email. And for large prey, "the spider will attach additional pre-tensioned threads to the prey which allows the spider to effectively hoist the prey off the ground," to keep it out of reach of pests and parasites, he said. 

The remains of the baby bat's body fell to the ground by the next day, but at that time, an adult bat had become trapped in the same web, Waddams noticed. In this case, the bat was still alive and not yet swaddled in silk when he observed the animal, so he scooped the bat from the web and placed it on the adjacent wall. The rescued animal then crawled back up toward its roost. 

The researchers identified the bats as either common pipistrelles (Pipistrellus pipistrellus) or soprano pipistrelles (Pipistrellus pygmaeus), which are two small, superficially indistinguishable bat species found in Britain. 

Pipistrelle bats are protected under the Wildlife and Countryside Act and the Conservation of Habitats and Species Regulations, according to the statement. This means that people can incur fines or prison time if they capture, injure or kill the bats, or if they damage or obstruct access to their breeding or resting places, for instance, according to Natural England and Department for Environment, Food & Rural Affairs.

"This study presents yet another example of the invasive impact by the noble false widow spider on native species," Dunbar said in the statement. In a previous study, published in 2018 in the journal Biology and Environment: Proceedings of the Royal Irish Academy, the team reported that the spider also preys on the viviparous lizard (Zootoca vivipara), a protected species in Ireland.  

"We know they are much more competitive than native spiders, and this further confirms their impact on prey species," Dunbar said.

Species of bat-eating spiders have been identified on every continent except Antarctica, and the arachnids typically prey on small or juvenile insect-eating bats that are unfortunate enough to get snagged in their webs, Live Science previously reported. Now, S. nobilis joins the list of spiders that pose a threat to the fuzzy, flying mammals.   

Editor's note: This article was updated on March 7, 2021 with additional quotes from John Dunbar. The original story was posted on March 3. 

Originally published on Live Science. 

Researchers have discovered a new species of parasitic worm that makes its home in the mouths of tarantulas — then slowly starves the spiders to death.

The worms first appear as white splotches around a tarantula's mouth, according to a new study published Jan. 17 in The Journal of Parasitology. After being infected, the arachnid host loses control of the appendages that control its fangs, then stops eating. Infected tarantulas may also show other strange behaviors, such as walking on their tiptoes, the study authors wrote.

From there, it's a slow tiptoe toward certain death.

"It may take months because tarantulas don't have to eat particularly often," study co-author Adler Dillman, a parasitologist at the University of California, Riverside (UCR), said in a statement. "However, if they get this infection, they will die of starvation."

Dillman and his colleagues first took note of the killer worms in 2018, when a wholesale tarantula breeder reported multiple unusual deaths among his stock. Each of the affected tarantulas showed a strange white discharge around their mouths. This wasn't spider spit-up, Dillman realized right away: It was a tangled mass of parasitic worms called nematodes, living inside the spiders' fly-holes.

"Nematodes have been around for hundreds of millions of years [and] evolved to infect every kind of host on the planet including humans," Dillman said. "Any animal you know of on planet Earth, there's a nematode that can infect it."

Though more than 25,000 species of nematodes have been described to date, this is only the second species known to infect tarantulas, Dillman added. That gave his lab an exciting opportunity to get to know the elusive, spider-hunting worms.

The team learned that lab-raised nematodes were mostly hermaphrodites, meaning they produced both sperm and eggs, allowing them to self-fertilize their spawn. On average, each hermaphroditic nematode produced 160 offspring in its lifetime — which lasted about 11 days in the lab. (It's unclear how the worm's life span might change when living on a tarantula, the researchers noted.)

The researchers also learned that the nematodes only infected their hosts' mouth areas, leaving the rest of the spider untouched and unharmed.

Still, because of the newly discovered worm's spider-slaying prowess, the team gave the species a name with a bit of Hollywood cache: Tarantobelus jeffdanielsi — named for American actor Jeff Daniels.

"When I first heard a new species of nematode had been named after me, I thought, 'Why? Is there a resemblance?'" Daniels joked in a statement to UCR.

In reality, the name is an homage to Daniels' starring role in the 1990 comedy thriller "Arachnophobia," in which his character saves a small town from a deadly spider infestation.

"Honestly, I was honored by their homage to me and Arachnophobia," Daniels added. "And of course, in Hollywood, you haven't really made it until you've been recognized by those in the field of parasitology."

Originally published on Live Science.

Buried in Australia's so-called dead heart, a trove of exceptional fossils, including those of trapdoor spiders, giant cicadas, tiny fish and a feather from an ancient bird, reveal a unique snapshot of a time when rainforests carpeted the now mostly-arid continent. 

Paleontologists discovered the fossil treasure-trove, known as a Lagerstätte ("storage site" in German) in New South Wales, in a region so arid that British geologist John Walter Gregory famously dubbed it the "dead heart of Australia" over 100 years ago. The Lagerstätte's location on private land was kept secret to protect it from illegal fossil collectors, while scientists excavated the remains of plants and animals that lived there sometime between 16 million and 11 million years ago.

The researchers unearthed remains that are unique in the Australian fossil record for the Miocene Epoch (23 million to 5.3 million years ago), they reported in a new study. Most of the prior Miocene finds that other scientists have unearthed in Australia were bones and teeth from larger animals — which are commonly preserved in Australia's dry landscapes. However, the new cache held fossils of small and delicate creatures such as spiders and insects, as well as flora from the Miocene rainforest. 

Related: 15 incredible places that are frozen in time

By examining the well-preserved fossils with scanning electron microscopes (SEM), the study authors were able to image details as fine as individual cells and subcellular structures. Some of the images even revealed animals' last meals, such as fish, larvae and a partially digested dragonfly wing preserved inside fishes' bellies. In other fossilized scenes, a freshwater mussel clung to a fish's fin, and pollen grains were stuck to insects' bodies.

"This site gives us unprecedented insight into what these ecosystems were like," lead study author Matthew McCurry, a curator of paleontology at the Australian Museum, told Live Science in an email. "We now know how diverse these ecosystems were, which species lived in them and how these species interacted."

Paleontologists first visited the site — now named McGraths Flat — in 2017, after a farmer reported finding fossilized leaves in one of his fields. When the scientists investigated, "we were pleased to discover that the site yields a much wider range of fossils, including the remains of insects, spiders and fishes," McCurry said. 

The fossil-bearing rock layer measures between 11,000 and 22,000 square feet (1,000 and 2,000 square meters), and paleontologists have thus far excavated just over 500 square feet (50 square m), according to McCurry. A matrix of iron-rich rock called goethite surrounded the fossils on top of a layer of sandstone. Plants and animal remains in a stagnant pool were likely encased in iron and other minerals after runoff from nearby basalt cliffs drained into the pool, known in Australia as a billabong, which preserved them in exquisite detail. 

Now, millions of years later, researchers have begun piecing together the fossils to build a portrait of an extinct Australian rainforest. They found leaves from flowering plants, pollen, fungal spores, more than a dozen specimens of fish, "a wide diversity of fossilized insects and arachnids," and a feather from a bird that was about the size of a modern sparrow, the study authors reported. Analysis of the preserved leaves suggests that the average temperature at the time was about 63 degrees Fahrenheit (17 degrees Celsius).

"I find the spider fossils the most fascinating," McCurry told Live Science. Until now, only four fossil spiders were known from Australia, and researchers have so far found 13 spider fossils at McGrath Flats, McCurry said.

Preserved soft tissues in the feather and in the fishes' eyes and skin held another exciting detail: pigment-storing cell structures called melanosomes. Though the color itself isn't preserved, scientists can compare the shape, size and stacking patterns in the fossil melanosomes to those in modern animals. In doing so, paleontologists can often reconstruct the colors and patterns in extinct species, study co-author Michael Frese, an associate professor of science at the University of Canberra in Australia, said in a statement.

While much has been discovered at McGraths Flat, "this is really only the beginning of the work on the fossil site," McCurry said. "We now know the age of the deposit and how well-preserved the fossils are, but we have years of work ahead of us to describe and name all of the species we are finding. I think that McGraths Flat will become extremely important in building a more accurate picture about how Australia has changed over time."

The findings were published Friday (Jan. 7) in the journal Science Advances.

Originally published on Live Science.

Brazilian wandering spiders are aggressive spiders that belong to the genus Phoneutria, which means "murderess" in Greek.

These critters, also known as armed spiders or banana spiders, are some of the most venomous spiders on Earth. Their large mouthparts, or chelicerae, inflict painful bites loaded with neurotoxic venom that can be deadly to humans — especially children — although in most cases immediate medical care can prevent death with antivenom, according to a 2018 study in the journal Clinical Toxinology in Australia, Europe, and Americas.

Brazilian wandering spiders are frequently listed among the deadliest spiders in the world. They were named the world's deadliest spiders multiple times by Guinness World Records, although the current record-holder is the male Sydney funnel-web spider (Atrax robustus). But "classifying an animal as deadly is controversial," Jo-Anne Sewlal, an arachnologist at the University of the West Indies in Trinidad and Tobago, previously told Live Science. Each bite is unique, and the damage it causes depends on the amount of venom injected, Sewlal said. 

Classification/taxonomy

There are nine species of Brazilian wandering spider, all of which are nocturnal and can be found in Brazil. Some species also can be found throughout Central and South America, from Costa Rica to Argentina, according to a 2008 article in the journal American Entomologist. Study author Richard S. Vetter, a research associate in the department of entomology at the University of California, Agriculture and Natural Resources, wrote that specimens of these powerful arachnids have been mistakenly exported to North America and Europe in banana shipments. However, Vetter noted, in many cases of cargo infestation, the spider in question is a harmless banana spider (genus Cupiennius) that is misidentified as a Phoneutria. The two types of spiders look similar.

The taxonomy of Brazilian wandering spiders, according to the Integrated Taxonomic Information System (ITIS), is:

Kingdom: Animalia 

Subkingdom: Bilateria 

Infrakingdom: Protostomia 

Superphylum: Ecdysozoa 

Phylum: Arthropoda 

Subphylum: Chelicerata 

Class: Arachnida 

Order: Araneae 

Family: Ctenidae 

Genus: Phoneutria 

Species:

• Phoneutria bahiensis
• Phoneutria boliviensis
• Phoneutria eickstedtae
• Phoneutria fera
• Phoneutria keyserlingi
• Phoneutria nigriventer
• Phoneutria pertyi
• Phoneutria reidyi
• Phoneutria depilata, according to a 2021 study published in the journal ZooKeys, which found that Phoneutria boliviensis actually included two separate species from different habitats. 

Size & characteristics

Brazilian wandering spiders are large, with bodies reaching up to 2 inches (5 centimeters) and a leg span of up to 7 inches (18 cm), according to the Natural History Museum in Karlsruhe, Germany. The species vary in color, though all are hairy and mostly brown and gray, although some species have lightly colored spots on their abdomen. Many species have bands of black and yellow or white on the underside of the two front legs, according to the University of Florida. 

Behavior

These arachnids "are called wandering spiders because they do not build webs but wander on the forest floor at night, actively hunting prey," Sewlal told Live Science in an interview conducted in 2014, before her death. They kill by both ambush and direct attack.

They spend most of their day hiding under logs or in crevices, and come out to hunt at night. They eat insects, other spiders and sometimes, small amphibians, reptiles and mice. 

Research into one species of Brazilian wandering spider, Phoneutria boliviensis, revealed that these spiders eat a mix of arthropods and reptiles. DNA metabarcoding, a technique that examines the DNA and RNA in a sample, of the guts of 57 spiders identified 96 prey species, including flies, beetles, butterflies, moths, grasshoppers, locusts and crickets, according to research from the University of Tolima and the University of Ibagué in Colombia. Some of the female spiders also ate lizards and snakes.

While their bites are powerful and painful, "their bites are a means of self-defense and only done if they are provoked intentionally or by accident," Sewlal said.

When Brazilian wandering spiders feel threatened, they often assume a defensive position by standing on their hind legs and stretching out their front legs to expose their fangs, according to the 2018 study in Clinical Toxinology in Australia, Europe, and Americas. This posture is sometimes accompanied by side-to-side movements. The spiders can also jump distances up to 1.3 feet (40 cm). 

Mating

In the Brazilian wandering spider, just as in most spider species, the female is larger than the male. Males approach females cautiously when attempting to mate, according to the biology department at the University of Wisconsin-La Crosse. Males perform a dance to get females' attention, and males often fight each other over the female. The female can be picky, and she often turns down many males before choosing a mating partner. Once she does pick one, the male needs to watch out; females often attack the males once copulation is finished.

The female then can store the sperm in a separate chamber from the eggs until she is ready to fertilize them. She will lay up to 1,000 eggs at a time, which are kept safe in a spun-silk egg sac.

Brazilian wandering spiders typically live for one or two years.

Bites and venom

Brazilian wandering spiders' venom is a complex cocktail of toxins, proteins and peptides, according to the Natural History Museum in Karlsruhe, Germany. The venom affects ion channels and chemical receptors in victims' neuromuscular systems.

After a human is bitten by one of these spiders, they may experience initial symptoms such as severe burning pain at the site of the bite, sweating and goosebumps, Sewlal said. Within 30 minutes, symptoms become systemic and include high or low blood pressure, fast or a slow heart rate, nausea, abdominal cramping, hypothermia, vertigo, blurred vision, convulsions and excessive sweating associated with shock. People who are bitten by a Brazilian wandering spider should seek medical attention immediately.

Their venom is perhaps most famous for triggering painful and long-lasting erections. For that reason, in a 2023 study, scientists reported that they were testing the venom in humans as a potential treatment for erectile dysfunction in those for whom Viagra didn't work.

However, these bites are rare, and envenomations, or exposure to these toxins from a spider bite, are usually mild, Vetter said. For instance, a 2000 study in the journal Revista do Instituto de Medicina Tropical de São Paulo found that only 2.3% of people with bites who came to a Brazilian hospital over a 13-year period were treated with antivenom. (The other bites did not contain enough venom to require it.) Most of the bites were from the species P. nigriventer and P. keyserlingi in eastern coastal Brazil. About 4,000 bites reportedly happen each year in Brazil, but only 0.5% of those cases are severe, according to the 2018 study. Meanwhile, 15 deaths have been attributed to Phoneutria in Brazil since 1903, the 2018 study reported. 

"It is unlikely that the spider would inject all of its venom into you, as this venom is not only needed as a means of defense but to immobilize prey," Sewlal said. "So if it did inject all of its venom, it [would] have to wait until its body manufactured more before it could hunt." That would also leave the spider vulnerable to being attacked by predators.

Furthermore, Sewlal pointed out that venom production requires a lot of a spider's resources and time. "So if the spider were to attack frequently and use up all of its venom, it [would] be safe to assume that it has a ready food supply to replace the energy and resources used. This situation does not exist in the wild."

Additional resources

• Learn more about Brazilian wandering spiders from the University of Wisconsin-La Crosse.
• Read about several species of Brazilian wandering spiders, including several images of the arachnids at the University of Florida.
• Find a spider in your bananas? It may or may not be a deadly species, according to the University of California, Riverside.

This article was originally published on Nov. 20, 2014. 

Huntsman spiders are a group of large spiders in the family Sparassidae, which comprises more than 1,300 species. They are found in warm climates across the globe and owe their name to the way they chase their prey.

Rather than building a web and waiting for a meal to come to them like many other spiders, huntsman spiders actively seek out and run after prey using their long, spindly legs. Once they catch their target, these speedy spiders inject it with an immobilizing venom and then chow down on it.

The giant huntsman spider (Heteropoda maxima) is the largest known huntsman spider in the world and the largest spider by diameter, according to a 2017 review article. Its body grows to 1.8 inches (4.6 centimeters) in size and it has a leg span of up to 11.8 inches (30 cm), dwarfing the average 1-inch (2.5 cm) body and 5-inch (12.7 cm) leg span of other huntsman spider species. While the giant huntsman spider steals the prize for the biggest leg span of any known spider, the goliath birdeater tarantula (Theraphosa blondi) is the heaviest on record, weighing up to six ounces (170 grams) — as much as a small puppy.

Related: What is the deadliest spider in the world? 

The giant huntsman spider is elusive and thought to mostly dwell in caves. It was discovered in 2001 in Laos by arachnologist Peter Jäger, who heads the arachnology team at the Senckenberg Research Institute and Natural History Museum in Frankfurt, Germany. Since then, researchers have described other large huntsman spiders — including Cerbalus aravaensis, the largest known huntsman spider in the Middle East — but the giant huntsman spider still reigns supreme.

What do huntsman spiders look like?

Because of their size, huntsman spiders are sometimes incorrectly classified as tarantulas. One way to tell a huntsman from a tarantula is by the position of the creature's legs. While most spiders' legs bend vertically under their body, "huntsman spiders usually have legs that are splayed out to the sides, crablike," said Christy Bills, an entomologist and the invertebrate collections manager at the Natural History Museum of Utah. Because of this, huntsman spiders are also known as giant crab spiders. 

Huntsman spiders' legs also have twisted joints that enable the appendages to extend forward, and their alignment enables the spider to move side to side, similar to a crab. Males have longer legs than females, although the latter have larger bodies. "Colors and patterns vary," Bills said, but the spiders' legs are typically gray or brown, and banded.

Many huntsman spiders have flattened bodies to help them squeeze into tight cracks and holes, according to the Australian Museum. 

Classification/taxonomy

According to the Integrated Taxonomic Information System (ITIS), the taxonomy of giant huntsman spiders is: 

• Kingdom: Animalia
• Subkingdom: Bilateria
• Infrakingdom: Protostomia
• Superphylum: Ecdysozoa
• Phylum: Arthropoda
• Subphylum: Chelicerata
• Class: Arachnida
• Order: Araneae
• Family: Sparassidae
• Genus & species: Heteropoda maxima

Where are giant huntsman spiders found?

The giant huntsman was found in Laos, and most huntsman species are native to Asia. They are also prevalent in Africa, Australia and South America, according to Science Alert. They live in some warm American states such as Florida, California and Texas, and, according to the University of Florida, it is presumed that they were introduced from Asia. Folklore stories claim the spiders traveled from Asia in boxes of bananas, and because of that, they are sometimes called banana spiders. 

Related: Brown recluse spiders: Facts, bites & symptoms 

What environment do they live in?

Bills extolled the huntsman's speed: "They can often be quite large and very quick." In fact, the huntsman spider can move up to a yard (almost 1 meter) a second, she said. The spider typically lives under loose bark on trees, under rocks, in crevices and under foliage. Huntsman spiders, especially Australian species, are notorious for entering houses and cars. According to the Australian Museum, they have been "found hiding behind sun visors or running across the dashboard." These spiders can be social, and dozens will sometimes sit together on dead trees or stumps.

What do huntsman spiders eat?

The huntsman runs after or ambushes its prey, killing it with venom and strong mouthparts, called the chelicerae. Once captured, the prey will be injected with deadly venom from glands within the spider's body, according to the University of Florida. The huntsman can also be a valuable spider because it eats cockroaches, in addition to other spiders and domestic insect pests.  

Are huntsman spiders dangerous?

Huntsman are not deadly to humans. According to the Australian Reptile Park, although huntsman spiders are venomous and their bites can be painful to humans, they do not cause anything more serious than mild nausea or headaches. Usually localized swelling and pain are the only symptoms of a huntsman spider bite.

In most instances, a huntsman spider will attempt to run away from a human, rather than biting them, according to the Australian Museum. However, the females of these spiders are more likely to bite when they perceive a threat to their young.

In the event that someone does get bitten, they should try to remain as calm as possible. This is to prevent their heart rate from increasing and spreading the venom more quickly around the body.  Applying an ice pack can reduce the pain caused by the bite, but a pressure immobilisation bandage is not needed, according to Australia Wide First Aid.

How do huntsman reproduce?

Compared to other spider species that eat their mates, huntsman spiders are downright romantic. According to the Australian Museum, their mating ritual can last for several hours and involves lengthy caresses and other demonstrations of interest. The male drums his pedipalps — antennae-like appendages near the mouth — against tree trunks before inserting them into the female to fertilize her eggs.

After mating, the female lays up to 200 eggs and encases them in a large, oval, spun-silk sac. "Some huntsmans are dedicated mothers," Billa said. They "look after their egg sacs, guarding them fiercely." 

Related: Why do spiders have 8 legs? 

According to the University of Florida's Entomology and Nematology Department, some females carry the sac with them under their bodies, which severely restricts their movements. Others place the sac under a rock or piece of bark and stand over it, without eating, for up to three weeks. In both cases, females may become aggressive when guarding their egg sacs.

According to the Australian Reptile Park, at birthing time, the mother may tear the egg sac open to help her spiderlings emerge. She'll then stay with the babies for several weeks. Baby huntsmen are pale in color and darken with each molt. Huntsman spiders can live for more than two years.

Are huntsman spiders social creatures?

Sociality is rare in spiders, and huntsman spiders are no exception. Only five species are known to exhibit social behaviors, such as living in large family groups, according to a 2022 study. The social species include four huntsman spiders found in Australia — Delena cancerides (also known as the communal or social huntsman), D. lapidicola, D. melanochelis and D. spenceri — as well as an unidentified species from Madagascar in the genus Damastes.

Social huntsman spiders live in groups comprising a single mother and multiple clutches of babies. The offspring leave the family retreat after 5 to 12 months, depending on the species. Solitary huntsman spiders, on the other hand, do not form big groups and leave their mothers just a few weeks after they are born.

Additional resources

• Learn more about the giant huntsman at the Encyclopedia of Life.
• Here is a handy guide to identifying huntsman spiders and other arachnids 
• Check out the World Spider Trait database for more information and research about spiders from around the world 

Editor's note: This article was updated on May 22, 2024, to include new findings about the sociality of giant huntsman spiders.

Hundreds of Colombian tarantulas, giant cockroaches and scorpions that were crammed into a suitcase and illegally bound for Europe were seized last week by authorities at El Dorado International Airport in Bogotá, Colombia.

Airport police spotted the living cargo in luggage belonging to two German citizens who were leaving the country, and they alerted the Ministry of Environment, agency representatives said in a statement on Dec. 2. 

Authorities then confiscated more than 300 animals in 210 plastic containers that the travelers had stored between rolls of film. The tubs held 232 spiders — trapdoor spiders and tarantulas — 67 giant cockroaches, a scorpion with seven young, and nine spider eggs, according to the statement. Though the German citizens claimed that they were transporting the arthropods to Germany for research, they did not have the proper authorization for removing the animals from the country, ministry officials said.

Related: In photos: Tarantulas strut their stuff

"Despite, like these citizens, having supposed academic or research purposes, any investigation must have explicit permission from the environmental authorities," Secretary of the Environment Carolina Urrutia Vásquez said in the statement (translated from Spanish). The apprehended travelers didn't have the permits and licenses required in Colombia to collect and transport arthropods in Colombia, and they could face fines as well as civil and criminal prosecution for their actions, according to the statement.

Investigators determined that the smuggled arthropods had been collected in the northeast of Bogotá in Boyacá, in the municipality of San Luis de Gaceno. The illicit cargo included individuals in the scorpion family Buthidae; the giant cockroach family Blaberidae; and the spider families Barychelidae (trapdoor spiders) and Theraphosidae (tarantulas).

In September, Colombian authorities foiled another illegal export operation, confiscating 3,493 shark fins and 256 pounds (117 kilograms) of fish swim bladders that were headed from Bogotá's airport to Hong Kong. The airport "continues to be a focus of attention for wildlife trafficking in Bogotá," Secretary Urrutia Vásquez said in the statement. In 2021 alone, officials recovered more than 11,000 trafficked specimens at the El Dorado International Airport; of those, 7,058 were living, ministry officials reported.

Originally published on Live Science.

Ever seen a teeny, furry spider scampering across the floor? There's a good chance you've glimpsed a jumping spider. 

Jumping spiders are the largest family of spiders, with more than 6,380 species identified by science, according to the World Spider Catalog. The scientific name for the jumping spider family is Salticidae. With so many species, it's no surprise that jumping spiders vary widely in appearance, habitat and preferred prey. The largest, Hyllus giganteus, can be 0.98 inches (2.5 centimeters) in length, while smaller species, like the colorful Habronattus pyrrithrix, range from 0.19 to 0.3 inches (5 to 8 millimeters) in length. 

But what jumping spiders do have in common is their impressive eyesight. These arachnids always have four pairs of eyes, including a large, forward-facing principle pair that make the spiders look rather Muppet-like and cute. These large eyes make jumping spiders a standout among spiders.

"They make their living on foot," said Nathan Morehouse, a biologist at the University of Cincinnati who studies jumping spider vision. "They have to stalk and jump to capture their prey. … To do all of that, they need really exceptional vision. And their vision, depending on how you measure it, is the best for anything as small as they are." 

What do jumping spiders look like?

Jumping spiders are a diverse bunch. Some are drab, while others sport a dazzling array of colors and patterns, from the blue, red and yellow abdomen of the peacock spider (Maratus volans) to the black-and-white stripes of the zebra spider (Salticus scenicus). Saitis barbipes, a European species of jumping spider, sports a red "headband" of coloration and similarly hued stripes on its third pair of legs. Bagheera kiplingi, found in Central America, is striped with a brilliant emerald green. In many species, males are colorful, while females are often more drab. 

Jumping spiders do have a few things in common. They're usually small, often 0.5 inches (12.7 mm) or less in length. They're often fuzzy. And they're distinguishable by their distinct eye pattern of four pairs of eyes, in which the large middle pair sits close together at the front of the face. The face is fairly flat. 

How good is jumping spider vision?

Jumping spider eyes are, in a word, incredible. The spiders, despite their tiny size, are better at seeing patterns than elephants are, Morehouse told Live Science. Their pair of central eyes, known as the principle eyes, are almost like a pair of tiny binoculars: They have a large outer lens, then a smaller inner lens that magnifies the image from the outer lens and projects it onto the retina. The spiders are also unusual in that they have muscles attached directly to their retinas. That means they can move retinas up and down, side to side, focusing on different segments of the world without a hint of movement on the outside, Morehouse said — a handy ability for a hunter. Meanwhile, the spiders' secondary pairs of eyes are less acute, but they provide crucial peripheral vision, Live Science previously reported. 

Most species of jumping spider can see ultraviolet light and blues and greens. Some species, though, have evolved special tricks to expand their color vision. These, Morehouse said, tend to be the flashier species, such as the paradise jumping spiders (genus Habbernatus), which are often decorated in shades of red and orange. In some species, a random genetic mutation has introduced an extra copy of the gene that makes the proteins that allow for blue/green vision. This extra copy has then acquired mutations capable of detecting red and orange. Similar mutations allowed primates to develop color vision, Morehouse said. 

Other jumping spiders have hacked color vision by developing pigments that sit in front of their blue/green color receptors. These pigments let only red wavelengths of light through. Though the receptors aren't most sensitive to these wavelengths of light, they react to the stimulus anyway, cuing in the spider that red or orange is present. Birds and reptiles often use this strategy to expand their color vision.

Jumping spiders can also see depth, in a "totally unusual" way, Morehouse said. According to 2012 research, the spiders use something called "depth via image defocus." Here's how it works: Jumping spiders' retinas have four layers of photoreceptors. Because different colors of light have different wavelengths, each layer catches a different color of light in precise focus. In a jumping spider retina, the bottom two layers are both chock-full of green color receptors. But green light that hits one of those layers perfectly in focus will appear a teensy bit blurred on the other layer, and vice versa. The 2012 research found that the spiders use this difference in focus to detect depth. 

Where are jumping spiders found?

Jumping spiders are found all over the world, with the exception of Antarctica. They live in tropical forests, temperate forests, grasslands, scrublands and even deserts, where you might find the red-abdomened species Phidippus californicus hanging out on a shrub. They prefer outdoor habitats, but if they find themselves indoors, they'll often set up shop near a window or door, where there is more chance of catching prey, according to the National Pest Management Association. 

Do jumping spiders really jump?

Jumping spiders can live up to their name. These spiders don't hunt by snaring prey in a web, but rather they stalk their quarry and then leap. Despite their tiny body size, jumping spiders can leap up to 6.3 inches (160 mm), according to a 2018 paper in the journal Scientific Reports. The spiders often spin a little silk and set a thread-like "anchor" before they leap, which may help stabilize their flight and protect them in case their landing is off. Jumping spiders most often jump to catch their prey, but sometimes leap to flee danger. They can also be quite clever: Researchers in the 2018 study actually trained a jumping spider (Phidippus regius) to leap from platform to platform. They named the spider Kim.

What do jumping spiders eat?

Jumping spiders are carnivores. They typically eat small insects and other spiders their size or smaller. Some species punch about their weight, though. Many jumping spiders are good at snagging flies as prey, earning them the nickname "fly tigers," according to the University of Florida. The regal jumping spider (the same species as Kim) has been observed eating lizards and frogs two to three times its weight, according to research published in 2017 in the Journal of Arachnology. 

When it comes to diet, the strangest jumping spider is likely Bagheera kiplingi. This Central American spider specializes in noshing on the leaf-tips of acacia bushes, making it a rare example of a spider that eats its vegetables.

How do jumping spiders reproduce?

Mating is serious business for jumping spiders. In many species, males flash their brilliant colors and shimmy in elaborate courtship displays. The peacock spider, for instance, flips up its colorful abdomen and thrusts a pair of legs in the air like a music-video backup dancer, Live Science reported. Research suggests that male spiders will try these displays out on any female jumping spider they come across, regardless of species; this seems to be a way to maximize the chances of mating with the right female while keeping some distance to avoid being cannibalized by a hungry female of the wrong species. The display isn't only about looks. Research from 2005 showed that in some species of jumping spider, the vibrations from the males' dances are also crucial to keeping the females interested. The males drum on the ground, rub body parts together and vibrate their whole beings to "sing" to potential mates, said Damian Elias, who studies jumping spider mating behavior and communication at the University of California, Berkeley. 

"I liken it to a one-man band," Elias told Live Science. 

Elias and his colleagues are trying to understand why jumping spiders "turn everything up to 11" in the mating game, he said. The spiders' great vision, rare in the arachnid world, might be one reason, he said. Another is that jumping spiders are a lot more active than many spider species, which hang out in webbing and watch the world go by. 

"They are encountering a lot more habitats than a typical spider," Elias said. "That's probably a reason they've had to evolve such a variety of things." 

When a female shows interest, the male spider uses specialized appendages called pedipalps to transfer over a packet of sperm and webbing to a specialized pocket called an epigynum in the female. Females lay clutches of more than 100 eggs, which they protect with a cocoon of webbing and guard until hatching, according to BugGuide, a site run by Iowa State University. Some species mate multiple times, with the female choosing which sperm to use to fertilize her eggs after collecting several options. Others mate only once. 

Are jumping spiders venomous? Do they bite?

Jumping spiders have venom that they use to subdue their insect and spider prey. They very rarely bite humans, however, and will only do so if they are being hurt or crushed, according to the University of California, Irvine. Bites typically cause no symptoms, or they may cause a temporary, mosquito-bite-type welt. 

Additional resources

• Find out what would happen to a jumping spider on the International Space Station in this children's book "The Jumping Spider Who Learned to Hunt in Space" (Mims House, 2016).
• Read about jumping spiders and more than 100 spider families in "Spiders of the World: A Natural History" (Princeton University Press, 2020).
• Spider science educator Sebastian Echeverri of the Carnegie Museum of Natural History talks about the superpowers of jumping spiders in this 11-minute video.

Originally published on Live Science.

What has eight legs and fangs powerful enough to bite through a human fingernail? "Megaspider," an enormous funnel-web spider that was recently captured in Australia.

The Australian Reptile Park (ARP) in New South Wales is a public zoo that also houses a collection of funnel-web spiders; keepers milk the spiders for their venom, which is then processed to create anti-venom. This particular spider was donated by an anonymous benefactor and arrived last week at the park in a plastic tub as part of a weekly collection from spider drop-off points near Sydney, the Central Coast and Newcastle, ARP representatives said on Nov. 11 in a statement.

Even seasoned spider keepers were astonished by the spider's size, according to the statement. The giant arachnid measured just over 3 inches (8 centimeters) from foot to foot — most funnel-web spiders are typically between 0.4 and 2 inches (1 and 5 cm) wide — and its curved fangs were 0.8 inches (2 cm) long. 

Related: Weird and wonderful: 9 bizarre spiders

"In my 30+ years at the Park, I have never seen a funnel web spider this big," Michael Tate, an ARP education officer, said in the statement. Park keepers promptly named the sizable arachnid female "Megaspider," but they don't know where she was found or who captured her; she had been boxed up in a Tupperware container without any labels or information about her captor, and there were no clues to connect her to any of the drop-off sites along the route, according to the statement.

"We are really keen to find out where she came from in hopes to find more massive spiders like her," Tate said.

Funnel-web spiders — which comprise about 40 species in the genera Hadronyche and Atrax — live in eastern Australia, and some species deliver a bite so toxic that it can kill an adult human within 15 minutes, according to the Australian Museum. All funnel-web spider species have glossy, nearly hairless bodies that vary in color from brown to deep black, and they have eight eyes arranged in two rows of four eyes each. The spiders are active year-round and live in burrows in moist, cool habitats, surrounding their tunnel openings with a network of silk strands. When a passing insect or other animal touches the silk, the vibrations alert the spider in the burrow, according to the Australian Museum.

ARP is Australia's only source of raw funnel-web spider venom for anti-venom serum production, according to the park statement. Keepers milk the spiders weekly and then ship the venom to a lab in Melbourne that produces the anti-venom by injecting very small doses into rabbits, so that the animals develop antibodies. These antibodies in the rabbits' blood can then be processed into a serum that neutralizes the venom's toxins in humans, according to NPS MedicineWise, an Australian nonprofit funded by the national Department of Health.  

Since the ARP program began in the 1950s, its anti-venom is estimated to have saved 25,000 Australians who were bitten by funnel-web spiders, and the antidote still saves approximately 300 lives each year.

Recent rainy weather and intense humidity in eastern Australia has created highly favorable conditions for the continent's funnel-web spiders, according to the statement. Members of the public who wish to safely collect spiders for the anti-venom program are advised to exercise extreme caution, by using glass jars (which the spiders can't climb or jump out of once they've been captured) and wearing protective clothing, such as gardening gloves and long pants, according to the New South Wales Department of Planning, Industry and Environment.

The park is especially interested in supersize arachnids like Megaspider, which have bigger reservoirs of venom for the milking program, Tate said.

"If we can get the public to hand in more spiders like her, it will only result in more lives being saved due to the huge amount of venom they can produce," he said.

Originally published on Live Science.

Millions of giant spiders have invaded North Georgia, terrifying residents and spinning webs as thick as 10 feet (3 meters) deep.

Porches, power lines, mailboxes and vegetable patches across more than 25 counties in the state have been draped with the dense, wheel-shaped webs of the bright-yellow Joro spider (Trichonephila clavata), an invasive species originating in East Asia.

The first of the 3-inch (7.6 centimeters) spiders was spotted 80 miles (128 kilometers) northeast of Atlanta in 2014; it likely hitchhiked there inside a shipping container, its discoverer, Rick Hoebeke, the collections manager at the Georgia Museum of Natural History said in a statement. 

Related: See photos of spiders eating bats

Since then, the spider's population and range have expanded steadily across the state, but nothing prepared residents or researchers for the number of spiders they would face this year. Will Hudson, an entomologist at the University of Georgia, said his porch became unusable after being covered by a blanket of webs 10 feet (3 m) deep, and he claims to have killed more than 300 spiders. 

"Last year, there were dozens of spiders, and they began to be something of a nuisance when I was doing yard work," Hudson said in the statement. "This year, I have several hundred, and they actually make the place look spooky with all the messy webs — like a scene out of 'Arachnophobia.'" 

Common to China, Taiwan, Japan and Korea, Joro spiders are part of a group of spiders known as "orb weavers" because of their highly symmetrical, circular webs. Though they are venomous, they use the venom only to immobilise the prey they snare in their webs. The venom poses no threat to human beings, dogs or cats unless they are allergic to it. While the spiders may nip if threatened, their bites are not often strong enough to break the skin.

Most of Georgia's Joro spiders will probably die off by late November, but this is far from the last we will see of them. Now that the spiders have gained a foothold (or eight) in the U.S., experts believe that the arachnids could spread even farther into other states with similar climates. Female Joros lay egg sacs, spun together with silk, that contain at least 400 babies. When the hatchlings emerge in the spring, they ride the wind on a strand of silk, floating across enormous distances, much like the baby spiders in the E.B. White novel "Charlotte's Web".

A lot of invasive species tend to destabilize the ecosystems they enter, but some scientists are optimistic that the spiders could actually bring unexpected benefits. Nancy Hinkle, an entomologist at the University of Georgia, said Joro spiders kill off mosquitoes, biting flies and invasive brown marmorated stink bugs, which have no natural predators and are known for damaging crops.

"Joro spiders present us with excellent opportunities to suppress pests naturally, without chemicals, so I'm trying to convince people that having zillions of large spiders and their webs around is a good thing!" Hinkle said in the statement.

Originally published on Live Science

Arachnophobia is a fear of arachnids — a group of arthropods that includes spiders, scorpions, ticks and mites. From the Greek word arachne, meaning spider, and phobos, meaning fear, arachnophobia can be a debilitating condition for some. 

More than 10 million people in the United States suffer from some kind of phobia, the American Psychological Association reported, and 40% of these phobias are related to creepy-crawly critters like insects, snakes and, of course, spiders. 

Related: What really scares people: Top 10 phobias

Why are people afraid of spiders?

So why have some people developed such a deep-seated fear of spiders and their eight-legged friends? 

"We know many species of spiders are poisonous and bite, and we know this from direct experience, science, biology, TV and seeing other people get bitten," Dr. Alan Manavitz, a clinical psychiatrist at Lenox Hill Hospital in New York City told Psycom, a mental health website. "Therefore, when we see a spider near us, a natural response is to feel fear and avoid the spider."

One theory suggests that nurture instead of nature may be to blame. (The 1990 film Arachnophobia certainly didn't put arachnophobes at ease.) The condition is likely to be more prevalent in the United States than in Cambodia, for instance, where tarantulas and scorpions are considered a delicacy, The Washington Post reported. 

Another theory suggests that our fear of the creepy-crawly arachnids may have helped us stay alive long ago. But although most spiders have venom, few actually have fangs large enough to pierce our skin. Of the 35,000 spider species in the world, only a dozen of them pose a risk to humans. Evolutionary psychologists have suggested that our early ancestors may not have been able to tell which spiders' bite would have rendered harm, leading them to develop a fear of all spiders. And some research supports this hypothesis. 

Related: An Australian man screamed so loud at a spider that the cops showed up

For example, when a team of scientists at the Max Planck Institute for Human Cognitive and Brain Sciences in Germany showed a group of babies images of spiders, flowers, fish and snakes, the infants' pupils dilated the most when they were shown images of the spiders and snakes. The researchers said this suggests people inherently develop fears of such creatures, Live Science previously reported. 

A 2016 study published in the journal Biological Psychology found that arachnophobes also overestimate the size of the spiders they come into contact with. "This study revealed how perception of even a basic feature such as size is influenced by emotion, and demonstrates how each of us experiences the world in a unique and different way," Tali Leibovich, study author and scientist at Ben Gurion University of the Negev in New York City said in a statement. 

Related: The greater the fear, the larger the spider

So what exactly is it about spiders that inspires such a negative reaction? It all comes down to the "disgust emotion," according to Psychology Today. Several research articles have shown that there isn't really one thing about spiders that triggers the disgust emotion. Some blame a tarantula's hairiness, some point to their venom and others blame their skittish movement. All of which suggests that instead of fear, what people may be feeling is disgust. 

An arachnophobe's response to seeing a spider is often visceral. Phobias can induce a number of physical reactions, including nausea, accelerated heart rate and dilated pupils. Other reactions to the sight of these animals include wrinkling of the nose (thought to help prevent foul smells and pathogens from entering) and frowning, which could have helped toxic liquids drip from the lips of our ancient ancestors. 

Can arachnophobia be cured?

Researchers have relied on many methods to help patients conquer their fear of spiders. 

Exposure therapy is often lauded as the most successful treatment of the condition. In exposure therapy, patients with the phobia are exposed to the thing they fear — in this case, spiders — in a safe and controlled setting. The thought is that patients can rewire their brain, and create a "new safe memory that resides in [their] brain alongside the bad memory," opinion columnist Richard A. Friedman wrote for The New York Times.

Related: New Rx for spider fears? Shout it out

In 2014, scientists reported that a man was cured of his arachnophobia after doctors removed a chunk of his brain. According to the case study, published Oct. 5, 2014, in the journal Neurocase, doctors scooped a piece of tissue out from the left side of the man's amygdala, to alleviate seizures caused by sarcoidosis. After the procedure, his fear of spiders turned to fascination. 

A 2016 study in the journal Biological Psychiatry reported that patients once fearful of spiders were able to touch a tarantula within days of taking the drug propranolol while also being exposed to a tarantula for two minutes at a time. At the end of three months, the patients held the tarantula. After a year, the study reported, their fear subsided entirely. 

Related: Spider phobia cured with 2-hour therapy

For some, the movie "Spiderman" has helped diminish the paralyzing effects of arachnophobia. In 2019, a study published in the journal Frontiers in Psychiatry reported that watching clips from either Spider Man or Ant Man helped people alleviate symptoms of the condition. The team of scientists asked participants to take a survey about their fear before and after watching a clip from Marvel's Spider Man. Participants reported fewer symptoms after watching just a seven second clip from the movie. 

Technology has become increasingly vital as a treatment for arachnophobia. As virtual reality has become more and more popular, scientists are exploring ways to dampen and even cure the effects of arachnophobia by tapping into the virtual world. 

Additional resources

• Learn more about phobias, in general, from the U.S. National Library of Medicine.
• Read more about specific phobias and how common they are from the National Institute of Mental Health.
• Find helpful resources for supporting mental health and treating mental health disorders at MentalHealth.gov. 

Big-eyed spiders were likely guarding their egg sacs and possibly caring for already hatched spiderlings when they were trapped in sticky tree resin some 99 million years ago. That resin hardened, locking up those arachnid mamas in four chunks of amber recently mined in Myanmar, and now considered the oldest evidence of maternal care in spiders, researchers say. 

Although the finding isn't unexpected, given that many spider mothers care for their offspring nowadays, "it's lovely to have actual physical evidence through these little snapshots in the fossil record," study co-researcher Paul Selden, a distinguished professor emeritus of the Department of Geology at the University of Kansas, told Live Science.

Related: 10 animal mothers that carry babies on their backs

Of the four amber chunks, the most extraordinary is a piece holding a large female spider with part of an egg sac under her, Selden said. This spider's facial appendages, spineless legs and trichobothria, or "sensing hairs," indicate that she is a member of the Lagonomegopidae family, a now-extinct group of spiders that lived in the Northern Hemisphere during the Cretaceous period (145 million to 66 million years ago). The mother's protective stance over her egg sac is suggestive of maternal care, Selden said.

"The female holding onto an egg sac with little tiny spiderlings inside — that's exactly the position that you would find female spiders guarding their eggs," which may have also helped to keep the eggs warm, Selden told Live Science. "So, it really is a typical female spider behavior caught in an instant by this fossilization process."

The amber even preserved the silk thread that wrapped the spider's eggs together. Some scientists think that spiders originally used silk to bundle their eggs together, and then later used it for other purposes, such as webs, Selden noted.

The other three specimens hold spiderlings — one with 24, another with 26 and a third with 34 hatchlings — as well as a few silk spider threads, some arthropod legs and a wasp. It's likely that each piece contains a unique group of spiderling siblings, as the hatchlings in each specimen are about the same size. They also have Lagonomegopidae features, including two large eyes at the front of the head, much like jumping spiders today, the researchers said. These large eyes indicate the lagonomegopid spiders were likely free hunters rather than web builders, as web-building spiders typically have poor vision.

One of the amber specimens with hatchlings contains spider silk entwining pieces of detritus, which may have been part of a nest that the mother built to guard her egg sac. This suggests that the hatchlings stayed with their mom in the nest after hatching, rather than immediately dispersing, the researchers said.

However, these spiders met a sticky end when they became trapped in tree resin, which eventually hardened into amber. The hatchlings likely died soon after they emerged from their eggs, and some of the arthropod appendages preserved next to them might be their mothers' legs, the researchers said.

Related: Incredible photos of peacock spiders 

Ethical considerations

The four amber pieces were mined in Tanai, a village in northern Myanmar before 2017, when the armed forces of Myanmar, known as the Tatmadaw, seized control of the country's amber mines and began pocketing the profits. Scientists are heavily discouraged from studying amber fossils mined after the takeover, to avoid funding the Tatmadaw, who took over the entire country of Myanmar (not just the mines) in a military coup in February 2021, according to a letter from the Society of Vertebrate Paleontology. 

The four amber specimens are now housed at the Key Laboratory of Insect Evolution and Environmental Changes, at the College of Life Sciences at Capital Normal University in Beijing, China, where study co-researcher Dong Ren is a curator.

The study will be published online Wednesday (Sept. 15) in the journal Proceedings of the Royal Society B: Biological Sciences.

Originally published on Live Science.

Venomous spiders prey upon snakes many times their size, a new study finds — and often emerge victorious against snakes as venomous as they are.

The study researchers found 319 records of spiders killing and feasting upon snakes, 297 of which were naturally occurring events in the wild. (The remaining 22 were staged in captivity.) About a third of those examples came from scientific observations published in journals, while the rest were found on news or social media sites.

"The longer I deal with this problem, the more I realize that certain spiders accomplish such incredible feats," said study senior author Martin Nyffeler, a conservation biologist at the University of Basel who has previously reported on spiders eating bats and other vertebrates.

Related: See photos of spiders eating bats

Mighty spiders

Snacking on snakes was remarkably widespread, with more than 30 spider species engaging in the practice in natural conditions, and another 11 taking the opportunity in captivity, Nyffeler and University of Georgia herpetologist J. Whitfield Gibbons reported this month in the Journal of Arachnology. Widow spiders were the most frequent spider-killers, responsible for about half of the snake deaths; this group includes the infamous hourglass-marked black widows (Latrodectus mactans, L. Hesperus, L. variolus) as well as relatives like the African button spider (L. indistinctus). These spiders are small, 0.4 inches (1.1 centimeters) in size at most, and they typically target small, young snakes, but their venom is deadly enough to kill much larger animals.

Related: See photos of the spiders feasting on snakes

Members of the tarantula family were responsible for another 10% of snake kills. These larger spiders do not build webs, but hunt prey actively on the ground or in trees. Another 8.5% of predation incidents were carried out by large orb-weaver spiders, which are also known to catch and eat bats and birds. These spiders weave large and very strong circular webs. Once the spiders kill the snakes, they suck out their innards just as they would an insect.

Reports of spiders eating snakes came from every continent except Antarctica, though half of the events reported occurred in the United States and almost a third occurred in Australia.

Sinuous victims

The researchers found evidence of spiders preying on 86 different species of snake, with snakes of the colubrid family being the most common victims. This family includes common species such as garter snakes (Thamnophis cyrtopsis) and rat snakes (Pantherophis guttatus), and their prevalence among spider victims likely reflects the fact that they are the most abundant snake family on all continents except Australia, Nyffeler and Gibbons wrote.

Most of the snakes attacked by spiders were babies or juveniles weighing less than a gram. But snakes sometimes took down large serpents, too: The largest victims were up to 3.25 feet (100 centimeters) long and weighed several ounces. Snakes that large were typically killed by orb-weavers or large tarantulas. Black widows could overcome snakes up to 30 times their own size by weight, and in one report, a cobweb spider (Steatoda triangulosa) entangled a 6-inch-long (15 cm) garter snake that was 355 times the spider's weight.

"Such an achievement is truly surprising," Nyffeler told Live Science. "It is almost unbelievable."

It could take anywhere from hours to days for the spider venom to kill the snakes, 30% of which were venomous themselves. Spider attacks were fatal to snakes in 86% of the reported incidents, while only 1.5% of snakes escaped on their own. Another 11% were rescued by human observers. Once a spider vanquishes a snake, it might take days to finish the meal.

In most cases, the researchers wrote, snakes are likely a rare and lucky meal for spiders that typically subsist on insects. But some spiders, particularly tarantulas, might make snakes a regular part of their diet. Australian redback spiders (Latrodectus hasselti), too, have been seen eating both lizards and snakes in large quantities.

Nyffeler has a snake phobia, he said, but the research mixed fear with fascination. "After studying the 'world of spiders' for a lifetime, it was very fascinating to get a glimpse into a parallel world, the 'world of snakes,'" he said.

Originally published on Live Science.

Spiders taking down and feasting on snakes is more common than researchers thought. Scientists have found more than 300 reported cases of 30 spider species preying on dozens of species of snakes. Some of these snakes are hundreds of times heavier than the arachnid preying on them, researchers found. Here's a look at some of the gruesome spider-on-snake feasting. The research, and photos, come from the following publication: Martin Nyffeler and J. Whitfield Gibbons (2021). Spiders (Arachnida: Araneae) feeding on snakes (Reptilia: Squamata). Journal of Arachnology 49, 1-27.

Black widow enjoys a snack

A black widow spider (Latrodectus geometricus) enjoys a meal of juvenile scarlet snake (Cemophora coccinea) in Georgia. Black widow venom contains a toxin called α-latrotoxin, which targets the nervous system of vertebrates, allowing these spiders to kill prey many times their size.

Eyelash viper gets trapped

A very venomous eyelash viper (Bothriechis schlegelii) gets trapped in the web of a golden silk orb-weaver spider in Costa Rica. The snake is 15.7 inches (40 centimeters) long. Its venom will likely do little good in this situation; there are no recorded instances of a snake successfully biting and injecting venom into a spider. 

Meal of a lifetime

A young Eastern garter snake (Thamnophis sirtalis) finds itself in a bad situation in Douglas, Georgia. A brown widow (Latrodectus geometricus), meanwhile, prepares for the meal of a lifetime. 

Tarantula v. snake

It's spider versus snake in the forest of the Pará state in Brazil. A tarantula (Theraphosa blondi) captures a juvenile false coral snake of the genus Oxyrhopus and carries it back to its burrow. Tarantulas don't weave webs, but rather they hunt prey on the ground or in trees.

Eating a baby snake

An adult female black widow (Latrodectus hesperus) feeds upon a young coral snake (Micruroides euryxanthus) near the Boyce Thompson Arboretum in Superior, Arizona. Most snakes successfully killed and eaten by spiders are babies or juveniles, though there are examples of snakes up to a meter long being taken. 

Widows are wicked

Widow spiders were responsible for about half of reports of spiders killing snakes. Here, a brown widow spider (Latrodectus geometricus) eats a Brahminy blindsnake (Indotyphlops braminus) in Zaachila, Oaxaca, Mexico. 

Goliath birdeater defeats vipter

The fer-de-lance (Bothrops atrox) is a pit viper with venom deadly to humans. In this staged photograph taken in Venezuela, though, a tarantula called the Goliath birdeater (Theraphosa blondi) easily defeats and consumes the dangerous viper.

Porch fight

Spiders don't just prey on snakes in exotic, wild locales. This scarlet snake (Cemophora coccinea) met its fate in the corner of a front porch in Gulf Breeze, Florida, where a black widow had set up shop.

Originally published on Live Science.

Spiderwebs are astonishingly complex constructions for objects that are so delicate. Even if webs don't literally spell out the words "terrific" and "radiant" like those in the book "Charlotte's Web" do, each is nonetheless an intricate engineering marvel. 

Building these strong yet ephemeral traps is a process that follows patterns shared among spider species. But is there room for individual variation that makes one species' web — or one individual spider's — recognizably different from another's? Are all webs identical, or is every spiderweb unique? And what factors cause spiders to vary their silky webs?

Related: Is it OK to throw house spiders outside?

There are approximately 48,000 known spider species worldwide, and while all spiders have silk-producing organs, known as spinnerets, and can produce several varieties of silk, not all spiders spin webs and lie in wait for their prey. Some spiders actively hunt for food, but they still use silk for making wind-sailing balloons, egg sacs or tiny "houses" to hide in, according to the Burke Museum of Natural History and Culture in Seattle. Other spiders use silk to build ingenious traps and tools, such as throwing nets, oxygen-holding nets for breathing underwater, web slingshots, silk-sealed leaf pockets for catching frogs, and silk pulleys capable of lifting lizards or small mammals.

Picture a spiderweb, and you might imagine a wheel-like structure with a spiral and spokes radiating outward from the center. These are known as orb webs, and they are made by fewer than 10% of known spider species, said Samuel Zschokke, an arachnologist in the Section of Conservation Biology at the University of Basel in Switzerland, where he researches and visualizes spiderweb construction. Orb webs are ideal for catching flying insects because they provide a wide area for prey capture and are nearly invisible, according to the Australian Museum in Sydney. 

And while they all may look very similar, no two are exactly alike.

Spiders that build orb webs typically follow a similar construction plan and create a similar shape. They begin with a few threads that center on a single point, in a "Y" shape; the spider then establishes a frame around the "Y," connecting a few more threads in the middle. "Then they make more threads from that middle to the frame — these are the so-called radii, or, spokes, if you're comparing it to a wheel," Zschokke told Live Science.

At this point, the spider moves to the middle and builds what is known as an auxiliary spiral from the inside out. This is a placeholding structure made of non-sticky silk. Once this temporary spiral is finished, the spider crafts a new, sticky spiral by working toward the center from the outer frame. When that spiral is finished, the spider removes the auxiliary spiral, Zschokke explained.

Related: 21 totally sweet spider superlatives

To some extent, all orb webs resemble each other, but there are details that differ between species. For example, spiders in the Cyclosa genus install a "decoration" in the middle of their webs made of prey leftovers and bits of leaves, which the spider may use as camouflage, Zschokke said. Other orb weavers incorporate a zig-zag structure into the web center, known as a stabilimentum. And while most orb-weavers produce webs that are perpendicular to the ground, some, such as Leucauge dromedaria, spin webs that are oriented horizontally, according to the Atlas of Living Australia.

Webs spun by spiders that are not orb weavers may look messy or haphazard by comparison. These web types include funnel webs, sheet webs, mesh webs and tangle webs, according to a study published in 2013 in the journal PeerJ.

An orb web's physical location can also influence what it looks like, Sebastian Echeverri, an arachnologist with the American Arachnological Society, told Live Science in a message on Twitter. 

"Even if the central pattern of the web is essentially the same between individuals, the lines of silk that anchor it to the environment will have to be different," Echeverri said. An orb-web spider that builds a web in flexible grass faces different construction challenges than a spider from the same species that spins its web in a tree; though those spiders would still follow the same basic construction plan, their webs would look somewhat different, Echeverri said.

Recently, researchers observed individual orb-weaving spiders in the species Uloborus diversus as they built webs — one per day, over several days. Those webs were similar but not identical, even when conditions stayed the same, day after day, the scientists reported May 25 in bioRxiv, a preprint website. 

In the study, which was not peer reviewed, the scientists said they captured small differences in the webs by tracking changes in the spider's position, but that didn't reveal why the spider varied its technique. Pinpointing the sensory cues that motivate slight changes in the spider's web spinning would require "a more detailed understanding of the spider's behavior," the researchers reported in the study.

Under the influence

Some very distinctive and unusual web variations in orb weavers have sprung from circumstances that most spiders usually don't encounter in nature: exposure to stimulants, sedatives and psychedelics. Since the late 1940s, scientists have manipulated spiders into designing webs that diverged wildly from the usual patterns by feeding the arachnids a smorgasbord of mind-altering drugs.

A 1971 study published in the journal Behavioral Science documented more than two decades of such experiments beginning in 1948, when H. M. Peters, a professor of zoology at the University of Tübingen in Germany, decided that he wanted his lab spiders to build their webs at a time that was more convenient for humans than the spiders' preferred pre-dawn schedule. 

So Peters gave the spiders amphetamines, reported study author Peter Witt, who in 1971 was a pharmacologist with the North Carolina Department of Mental Health in Raleigh. Witt collaborated with Peters in the spider experiments, and the two scientists co-authored a landmark 1949 study documenting how the Tübingen spiders responded to amphetamines.

Related: How do spiders make silk?

While stimulants didn't affect what time the spiders chose to spin their webs, "the webs were built in a way which seemed distorted beyond the range of variations in the geometric pattern which had been observed up to that time," Witt wrote, adding that "it took only a few days to prove that the phenomenon was reproducible." 

The 1948 discovery fueled Witt's curiosity about spiders' web spinning and what it could tell scientists about the ways that drugs alter behavior, and he continued investigating how drugs affected behavior in spiders and in people, according to a biography published in 2013 in the journal Archives of Environmental Health). In more than two decades of research, Witt and other scientists found that different drugs prompted different web-building techniques. 

For example, dextroamphetamine, a stimulant that is used to treat narcolepsy and ADHD, led to "irregular radius and spiral spacing," according to the 1971 study. Scopolamine, a medication for motion sickness, "caused wide deviation of spiral spacing distinctly different from amphetamine." By comparison, spiders that were given the hallucinogenic drug lysergic acid diethylamide — LSD — produced "unusually regular webs," Witt reported.

Decades later, researchers at NASA's Marshall Space Flight Center in Huntsville, Alabama revisited these experiments by dosing European garden spiders (Araneus diadematus) with caffeine, benzedrine, marijuana and the sedative chloral hydrate, according to a 1995 report published in the journal NASA Tech Briefs. Photos of the resulting webs revealed that caffeine was the biggest structural disrupter, the web's signature spokes and spirals replaced with a seemingly random hodgepodge of strands, according to the study.

While spiders normally don't build webs that are so dramatically distinctive (and wonky) without chemical assistance, they do craft a fresh web every night or so. That means a spider can produce about 100 to 200 webs over the course of its lifetime, depending on the species, so there's bound to be at least some variation from web to web — even if it isn't quite as extreme as a web spun by a spider that's high caffeine, Zschokke said.

"If you look close enough, each web will be somewhat different," he said.

Originally published on Live Science.

Many residents of Victoria, Australia, evacuated their homes to avoid disastrous floods last week — and upon their return, they found the land, trees and road signs coated in thick veils of shimmering spider silk, according to news reports.

Heavy rains and strong winds triggered flash floods in the Australian state last week, leaving tens of thousands of residents without power, The Guardian reported; two people died when their vehicles became inundated by the floodwaters. The Victoria State Emergency Service had issued flood warnings beforehand, specifically urging residents to evacuate from the Traralgon Creek area, located in the rural Gippsland region of Victoria, according to tweets from Darren Chester, the member of Parliament representing Gippsland.

As the residents of Gippsland evacuated their homes, local arachnids also fled for higher ground. Using a behavior called "ballooning," spiders clambered atop vegetation and flung fine silk threads into the wind; as the threads caught air, the spiders got plucked from their perches and lifted to safety, CNN reported.   

Related: 21 totally sweet spider superlatives 

"When we get these types of very heavy rains and flooding, these animals who spend their lives cryptically on the ground can't live there anymore, and do exactly what we try to do — they move to the higher ground," Dieter Hochuli, an ecologist at the University of Sydney, told CNN affiliate 7News. "This is a surprisingly common phenomenon after floods," he said, adding that sheetweb spiders — a family of arachnids in the genus Stiphidiidae — likely spun the abundance of silk.

When thousands of spiders balloon at the same time, their many silk threads can merge to form a "remarkable carpet of silk, called gossamer, covering shrubs or fields," according to the Australian Museum. Given how much gossamer accumulated in Gippsland, it's possible that millions of spiders took to the air to escape the floods, Ken Walker, a senior insects curator at Museums Victoria, told The Age, a Victoria-based newspaper.  

"To me, it's absolutely beautiful. A silken blanket that undulates throughout vegetation," Walker said. "It also shows the literally tens of thousands, if not millions, of spiders at ground level. Without spiders, we'd have plagues of insects," he added.

Local councillor Carolyn Crossley told BBC News that she noticed the "beautiful" sheets of spider silk while assessing flood damage in the area on Monday night (June 14). "The fact that it didn't separate — it was like these spiders had coordinated to make this incredible landscape art installation or something," she said. Crossley had witnessed this ballooning phenomenon before but never to such a dramatic extent, she said.

The billowing mats of spider silk should disintegrate sometime this week, BBC News reported. Meanwhile, Gippsland continues to recover from the severe flash floods.

Originally published on Live Science.