Whether it's having the "eye of the tiger" or being lionhearted, references to lions and tigers evoke power and determination. That's not surprising given these animals are both large, powerful felines. But they are distinct species. So what do these iconic cats have in common, and how are they different?

To answer this question, let's consider the two species' appearances, evolutionary histories and how they live their lives as kings of their ecosystems.

Appearance and anatomy

The most obvious difference between modern lions (Panthera leo) and tigers (Panthera tigris) is their distinct physical appearances, particularly their coats.

"Just looking at them, you can clearly tell that tigers have stripes and lions don't," Dell Guglielmo, a zookeeper who cares for lions and tigers at Smithsonian's National Zoo, told Live Science. "The lion males have the large huge mane, and the females do not." In contrast, male and female tigers look the same.

A tiger's stripes help the cat blend in among the patterns of shadows and light created by grasses and trees in the dense temperate and tropical forests of Asia where they live. The orange and brown or black stripes stand out to the human eye, but to a tiger's colorblind prey, orange appears green and blends in. The stripes are pigmented on their skin, too. Each tiger's stripe pattern is unique, Guglielmo said.

Lions' tawny coloring also serves as camouflage. Lions blend in with the dry grasses of Africa's open savannas.

On the inside, however, lions and tigers are very similar. "If you look at the skeletons, all cats essentially look the same," Z. Jack Tseng, an associate professor of integrative biology at the University of California, Berkeley, told Live Science. There's an unofficial saying among those who study cat fossils. If "you ask them to describe the cat family fossil record, usually people will say, 'Well, a cat is a cat is a cat,'" Tseng said. Even your pet cat is basically identical to a lion or tiger, skeletally speaking — just proportionally a lot smaller.

Evolutionary differences

Despite their similarities, "lions and tigers are not each other's closest relatives," Tseng said. Tigers are more closely related to snow leopards, while lions are grouped with leopards and jaguars.

Moreover, tigers emerged much earlier as a species than lions. "The oldest putative tiger fossils are around 2 million years old," Tseng said, "whereas lion fossils are probably no more than a million years old, probably younger than that."

When it comes to classifying cats, size matters. Lions and tigers belong to the Panthera genus, along with leopards, jaguars and snow leopards. The last common ancestor of all five species likely emerged at least 5.57 million years ago, a genetic modeling study found. Tseng and his co-authors modeled this age based on genetic sequences and anatomical data, such as characteristics of bones and teeth. No fossil has been found yet, but this ancestor was likely smaller than lions and tigers, Tseng said.

He noted that both species independently evolved to be large. Animals can grow in body size for a variety of reasons, including living in cooler climates, as this gives them a smaller surface area-to-volume ratio, which helps to reduce heat loss. "The fossil record is not detailed enough to say whether lions and tigers got large independently for the same reasons, but they probably followed one or more of these broader trends as they evolved," Tseng said.

Behavior

Lions and tigers behave quite differently in the wild. Lions live in social, matriarchal groups with multiple female relatives and one or two male adult lions who may leave if challenged by another male. That's where the mane can come in handy.

"Cats often go for the neck when they fight and when they kill their prey," Jacob Shanks, a wildlife care manager at San Diego Zoo Wildlife Alliance, told Live Science. "Male lions being social, there's a lot of battling for territory and access to reproduction and other resources, so the manes help protect against neck wounds."

Tigers have far less social interaction than lions do. Tiger cubs remain with their mother for two years before going their separate ways. As adults, tigers generally avoid each other, aside from breeding. When a tiger wants to approach another individual, it makes a puff-like sound, called a chuff, by pushing air through its nose. Tigers are "one of the only cat species that chuff," Guglielmo said. If the second tiger is OK with the first tiger moving closer, it will chuff back. "Lions don't use a chuff; they just use different body language or just walk up and see if it works," Guglielmo said.

Would tigers and lions ever meet in the wild? That's not likely, as they live in completely different parts of the world. Even in the fossil record, there is no overlap in their range, which prevents the two species from competing and breeding, Tseng said.

However, humans have artificially bred lions and tigers in captivity, creating a hybrid called a liger. "Hybridization doesn't exist in the wild," Shanks said. "I've never seen a case of wild lion-tiger hybridization." Making hybrids doesn't benefit either species, he added.

A key similarity between lions and tigers are the threats they face. Tigers are considered endangered, and lions are vulnerable, according to the International Union for Conservation of Nature. Both big cats face threats from human conflict, habitat loss and climate change. "They need active conservation to protect and to help improve if we're going to not have them slip away," Shanks said.

Think you know about lions and tigers? Test your smarts with our big cat quiz!

It's easy to think of pupils as simple holes that widen in the dark and shrink in the light. But if you look across the animal kingdom, you'll see a variety of pupil shapes: vertical slits in cats and snakes, horizontal rectangles in goats and horses, and W-shaped crescents in cuttlefish, for instance. The shape of an animal's pupil can reveal a lot about how that animal sees and what it needs to survive.

In a perfect optical system, the shape of the pupil shouldn't matter much. "In an ideal world, the way optics is generally taught, the pupil's sort of irrelevant because all the light should be coming to an exact point anyway," said Jenny Read, a visual neuroscientist at Newcastle University in the U.K.

But real eyes are imperfect — light coming through the pupil creates diffraction and defocus that different pupil shapes resolve in different ways. "It actually turns out to be really complicated," Read said.

One important factor is depth of field, Marty Banks, a professor emeritus of optometry at the University of California, Berkeley, told Live Science. His 2015 study in the journal Science Advances was the first to systematically explain why the orientation of an animal's pupil matters for survival.

Depth of field is most easily illustrated with a camera lens, where the camera's aperture acts as its pupil. A narrow aperture creates an image where things are in focus both far away from and near to the camera. A wide aperture puts one object in focus and blurs everything in the foreground and background. But when a pupil isn't perfectly round, it can produce more variation in focus, and some animals' eyes take advantage of that.

Ambush predators, like cats and snakes, have forward-facing eyes that judge distance by comparing the slight differences between their two views — a process called stereopsis. Because the eyes are side by side, the differences show up most clearly along vertical edges, which means those edges need to be sharp.

"How do you make sure they're sharp? Well, you [narrow] the pupil, and you increase the depth of field," Banks said. "But they only need to do it for the vertical contours. So it's really clever to stop the pupil down horizontally and leave it wide open vertically, because for the other contours where stereopsis is not useful, like for horizontal contour, now they can use blur to estimate the distance."

That's why the pupils of ambush predators are shaped like slits: Shrinking the pupil horizontally helps with stereopsis, while widening it vertically helps them estimate depth from blur.

However, this works best for predators close to the ground. Larger predators, like lions and tigers, tend to have round pupils because they look at the ground at a steeper angle that reduces the advantage of blur to estimate distance.

Prey animals have different priorities for survival, and the shapes of their pupils reflect that.

"For prey animals, it's more about field of view than it is about image sharpness," Banks said. "They need to be able to see panoramically along the ground because most of the predators that are going to approach them are going to be on the ground."

In contrast, the eyes of prey animals like goats, sheep and horses tend to be positioned on the sides of their head, and their pupils are shaped like a bar ‪—‬ wide horizontally and short vertically. That wide shape lets in more light from the horizontal plane in front of them and behind them to help them scan their surroundings, while the short vertical opening sharpens horizontal contours — basically the opposite of what predators' eyes do.

But there's a problem: A prey animal that's lowering its head to graze would turn its horizontal pupils sideways and ruin its ability to scan the horizon. However, these animals have evolved a surprising solution, Banks discovered: As the animal's head changes orientation, its eyes rotate in its sockets to compensate.

"They've developed this ability to move their eyes in opposite directions on the two sides of the head to keep the pupil parallel to the ground," Banks said.

There are other animals with even stranger pupil shapes, especially in the sea. Cuttlefish, for example, have W-shaped pupils. Scientists still don't have definitive answers for why.

"Some people have argued that it makes them less visible to other animals," Banks said. "I'm not sure I believe that a W somehow would be harder to see than a circle."

Other theories suggest that these pupil shapes might help reduce light from above to minimize scattering and improve contrast. One early theory proposed that the shape may help with color perception — cuttlefish have only one photopigment, which should mean they see only in black and white, despite their dazzling colors and knack for camouflage.

Banks' study focused on land animals, and he acknowledged that many aquatic pupils remain unexplained. Read suspects the unknowns go even further. "It makes you think what other abilities may be out there in animal eyes that we just have no ideas about," she said.

Animal quiz: Test yourself on these fun animal trivia questions

Lizards, birds and fish often sport vivid colors, from neon pink to deep violet, but most mammals are fairly drab. So why don't mammals match the vibrant hues of other animals?

A number of factors culminate in the browns, blacks and whites that make up most mammalian coats. The first has to do with color expression. Matthew Shawkey, an evolutionary biologist at Ghent University in Belgium, explained that animals generally express color in two main ways: through pigments and through structures. Pigments exist within the skin and coat of the animal itself and reflect and absorb light to create certain colors. Structural coloration, on the other hand, involves nanoscale shapes and patterns on top of skin, feathers or scales that can distort light to produce bright, iridescent colors.

Animals can use one method, or sometimes both, to express color. According to Shawkey, however, mammals don't really use either. Of the many color-producing pigments — such as carotenoids, porphyrins and pterins — mammals have just one type: melanin. The presence of that one pigment generates all of the colors seen in mammals, Shawkey said, and its absence creates the white regions seen in animals like zebras and pandas.

Moreover, the composition of the hairs that make up mammal fur limits the structural colors mammals can display. Hair is not a complex structure like feathers, scales and skin are, so it's not surprising that it cannot produce the nanoscale patterns necessary for structural color, Shawkey noted.

For example, mandrills (Mandrillus sphinx), which break the drab-mammal rule with their bright red and blue, have those colors only on spots without fur. Sloths, which sometimes have green patches, get this coloration from algae that grows on their fur, not from pigments or structures on the hairs themselves.

Evolution of color

So why don't most mammals have the tools to create vibrant hues? One hypothesis is that when mammals first evolved, dinosaurs were the apex predators and mammals were prey. To avoid being eaten, mammals spent more than 100 million years as primarily nocturnal animals (and most remain so today).

Those millions of years had a big impact on mammals' appearance. In a 2025 study co-authored by Shawkey and published in the journal Science, a research team compared pigment-storing structures called melanosomes in modern mammals to preserved melanosomes found in six Jurassic and Cretaceous-age mammal fossils. They found that all of the mammal fossils were some shade of brown or gray.

Because these prehistoric animals were living primarily in the dark, darker colors would have helped mammals avoid predators. "Any bright color would have been selected against," Shawkey told Live Science.

In the 66 million years since the nonavian dinosaurs went extinct, mammal diversity has exploded to over 6,000 species. Now, there are mammal species, both nocturnal and diurnal, that have no natural predators. However, mammals have remained mostly brown, gray and black.

This could be due to most mammals' continued lack of color vision, said Ted Stankowich, a behavioral evolutionary ecologist at California State University, Long Beach. Researchers speculate that mammals sacrificed some color vision in order to gain better night vision during the age of the dinosaurs. Most mammals still have dichromatic vision, meaning they only have two of the three types of cones that help the eye perceive color. Dichromats can't see colors such as red, orange, turquoise and purple, and generally can't see colors with as much saturation as trichromats, which have all three types of cones.

The purposes animals primarily use color for — attracting mates and other communications within their species, blending in with camouflage, and signaling to predators that they are poisonous or otherwise dangerous — don't work when their partner or predator can't see the colors they're using. Some mammals have actually used this lack of color vision to their advantage. For example, although tigers look orange to our trichromatic eyes, they look green to their mammalian prey, making them perfectly camouflaged amongst the grass when on the hunt.

Instead of using vibrant colors, Stankowich said, many mammals use patterns and contrasting colors, such as black and white or brown and yellow, to signal to each other. Skunks and polecats, for example, use black and white spots and stripes to let predators know they have a stinky trick up their sleeve. The African wild dog, known for its unique patterning, has a distinctly white tail that researchers think is used for signaling while on the hunt. The Indian giant squirrel, known for its high-contrast black, reddish brown and orange-yellow patterning, may use this as camouflage against various kinds of predators.

Because mammals have adopted new ways of color signaling, there might not be much of a reason for them to regain color vision. (The few mammals with trichromatic vision — primates, including humans and some monkeys — evolved color vision for very specific reasons.) Stankowich noted that the few mammals that display bright blues and reds, such as baboons, golden snub-nosed monkeys and mandrills, are also among the mammals with the best color vision.

Fluorescence and iridescence

Recent studies have highlighted some other exceptions. For example, many mammals fluoresce under ultraviolet light, which the human eye cannot detect but some other mammals can. Moreover, Jessica Dobson, an evolutionary biologist at Ghent University, and colleagues have discovered iridescence in a handful of mammal species not previously known to have this shimmery feature.

"It was a light-bulb moment," Dobson said of this iridescence discovery, which happened when she opened a museum drawer and sunlight hit the preserved pelts of several tropical rat species at just the right angle. Dobson isn't sure whether these iridescent colors serve any evolutionary purpose, but she said it is nonetheless exciting to know that there are still mammalian color mysteries to unlock.

"When you start looking, mammals are more colorful than we give them credit for," Dobson said.

Animal quiz: Test yourself on these fun animal trivia questions

Neanderthals, our extinct cousins, are often portrayed as eating nothing but meat — no fruit, no grains, no greens. But did Neanderthals really live on meat alone?

While there's plenty of evidence that Neanderthals regularly chowed down on meat, a growing body of research shows our close evolutionary relatives, who went extinct more than 30,000 years ago, also ate other parts of animals besides their meat, such as fat extract from the bone marrow, as well as other foods, including pistachios, lentils and wild peas.

Scientists can estimate the proportions of different foods eaten by ancient humans by analyzing the number of atoms with varying numbers of neutrons in their nuclei, known as isotopes, such as carbon-13 and nitrogen-15. The isotopes humans eat end up preserved in their teeth and bones. These isotopes act as chemical fingerprints, revealing what people and animals ate thousands of years ago.

"Multiple independent isotope studies now converge on the same conclusion," Ludovic Slimak, a paleoanthropologist at the University of Toulouse in France and author of "The Naked Neanderthal" (Penguin Books, 2023) and "The Last Neanderthal: Understanding How Humans Die" (Polity, 2025), told Live Science in an email. "Neanderthals consistently present the isotopic signatures of top-level carnivores."

At the site of Gabasa in Spain, for example, analyses of calcium, strontium and zinc isotopes showed that Neanderthals were hypercarnivores who survived mainly on meat and bone marrow. From what we know, Neanderthals were apex predators, Slimak said, much like wolves and hyenas, which sit at the top of the food chain with no natural predators.

This idea is supported by earlier nitrogen isotope studies, said Hervé Bocherens, head of the biogeology research group at the University of Tübingen in Germany.

Nitrogen comes in two stable forms, or isotopes: nitrogen-14 and the less common nitrogen-15. When animals eat other animals, the heavier nitrogen-15 slowly builds up in their bodies. That means animals that eat meat have more nitrogen-15 than plant eaters.

"In most Neanderthal specimens that have been analyzed, the nitrogen-15 content was higher than those measured in large carnivores, such as cave lions, cave hyenas or wolves," Bocherens told Live Science in an email. "The conclusion was that Neanderthals were 'more carnivore than the carnivores' (hypercarnivores)."

However, he added, this interpretation is too simple. Nitrogen levels can vary depending on which animals Neanderthals ate, not just how much meat they consumed.

"Woolly mammoths consistently exhibit the highest nitrogen-15 levels among herbivores, probably due to the consumption of plants with high nitrogen-15 levels," Bocherens said. The data suggest that Neanderthals were predators that consumed a higher proportion of mammoths than they did of other carnivores in the ecosystem, Bocherens added.

A 2025 study offered a different explanation for Neanderthals' unusually high nitrogen-15 levels: They may have eaten maggots, either by accident, in the process of eating rotting meat, or on purpose.

"Both rotting meat and especially maggots feasting on the rotting meat have high nitrogen levels and any Neandertal eating those foods regularly would have an isotopic signature that is off the charts," April Nowell, a Paleolithic archaeologist and professor of anthropology at the University of Victoria in British Columbia, told Live Science in an email.

But could Neanderthals survive on a solely meat-based diet?

"They could not if they had a similar physiology as modern humans, which is likely," Bocherens said. "There is a need for dietary sources of energy." Eating too much protein without enough fat and carbohydrates, which supply most of our energy, can lead to a fatal condition known as protein poisoning or "rabbit starvation."

Their solution, scientists think, was fat. At one 125,000-year-old German site, researchers found evidence that Neanderthals systematically broke animal bones to extract fat from bone marrow. Animal brains were another probable source of fat, Bocherens said.

When whole carcasses are consumed, including marrow and fat reserves, an animal-based diet is perfectly viable, Slimak said.

Neanderthals ate more than meat and fat

Neanderthals may have found creative ways to balance their nutrition. They might have eaten the stomach contents of their plant-eating prey, Chris Stringer, a research leader in human origins at the Natural History Museum in London, told Live Science in an email.

Scientists agree that Neanderthals also ate plants when they were available. "There is extensive evidence for plant eating by Neanderthals," Nowell said. That evidence includes actual plant remains discovered in caves, microscopic traces left on stone tools, and even plant residues preserved in dental plaque and fossilized feces.

Food remains found in modern-day Israel suggest Neanderthals ate legumes, acorns and pistachios, Nowell said. In Greece and Iraq, plant remains suggest they soaked, pounded and ground lentils, nuts and grasses — a form of food preparation that may have helped remove bitter flavors. In Gibraltar, researchers found the charred remains of edible plants like wild olives and stone pine nuts. In Italy, starch grains found on stone tools hint that Neanderthals were even making a kind of flour.

At El Sidrón Cave in Spain, chemical analyses of dental plaque revealed that Neanderthals ate plants like yarrow and chamomile, likely for medicinal purposes. And, at an open-air archaeological site called El Salt in Alicante, Spain, researchers found significant levels of plant sterols (fats in plants that are similar to cholesterol) in fossilized Neanderthal feces.

In warmer regions, Neanderthals likely gathered a wider range of plant foods, including seeds, starchy root vegetables like tubers, and even dates in the warmest regions, said Robert Power, a research fellow in the School of Archaeology at University College Dublin.

Although Neanderthals were skilled hunters who relied heavily on animal foods, "they varied their diets depending on where and when they lived, adapting to local foods and changing with the seasons," Nowell said.

Neanderthal quiz: How much do you know about our closest relatives?

Long-spined sea urchins have emerged as an environmental issue off Australia's far south coast. Native to temperate waters around New South Wales, the urchins have expanded their range south as oceans warm. There, they devour kelp and invertebrates, leaving barren habitats in their wake.

Lobsters are widely accepted as sea urchins' key predator. In efforts to control urchin numbers, scientists have been researching this predator-prey relationship. And the latest research by my colleagues and I, released today, delivered an unexpected result.

We set up several cameras outside a lobster den and placed sea urchins in it. We filmed at night for almost a month. When we checked the footage, most sea urchins had been eaten — not by lobsters, but by sharks.

This suggests sharks have been overlooked as predators of sea urchins in NSW. Importantly, sharks seem to very easily consume these large, spiky creatures — sometimes in just a few gulps! Our findings suggest the diversity of predators eating large sea urchins is broader than we thought — and that could prove to be good news for protecting our kelp forests.

Related: 'It's like we opened a buffet': Sharks in Gulf of Mexico learn to steal food from fishing nets

A puzzling picture

The waters off Australia's south-east are warming at almost four times the global average. This has allowed long-spined sea urchins (Centrostephanus rodgersii) to extend their range from NSW into waters off Victoria and Tasmania.

Sea urchins feed on kelp and in their march south, have reduced kelp cover. This has added to pressure on kelp forests, which face many threats.

Scientists have been looking for ways to combat the spread of sea urchins. Ensuring healthy populations of predators is one suggested solution.

Overseas research on different urchin species has focused on predators such as lobsters and large fish. It found kelp cover can be improved by protecting or reinstating these predators.

In NSW, eastern rock lobsters are thought to be important urchin predators. The species has been over-fished in the past but stocks have significantly bounced back in recent years.

But despite this, no meaningful reduction in urchin populations, or increase in kelp growth, has been observed in NSW.

Why not? Could it be that lobsters are not eating urchins in great numbers after all? Certainly, there is little empirical evidence on how often predators eat urchins in the wild.

What's more, recent research in NSW suggested the influence of lobsters on urchin populations was low, while fish could be more important.

Our project aimed to investigate the situation further.

What we did

We tied 100 urchins to blocks outside a lobster den off in Wollongong for 25 nights. This tethering meant the urchins were easily available to predators and stayed within view of our cameras.

Then we set multiple cameras to remotely turn on at sunset and turn after sunrise each day, to capture nocturnal feeding. We used a red-filtered light to film the experiments because invertebrates don't like the white light spectrum.

We expected our cameras would capture lobsters eating the urchins. But in fact, the lobsters showed little interest in the urchins and ate just 4% of them. They were often filmed walking straight past urchins in search of other food.

Sharks, however, were very interested in the urchins. Both crested horn sharks (Heterodontus galeatus) and Port Jackson sharks (H. portusjacksonii) entered the den and ate 45% of the urchins.

As the footage below shows, sharks readily handled very large urchins (wider then 12 centimetres) with no hesitation.

Until now, it was thought few or no predators could handle urchins of this size. Larger urchins have longer spines, thicker shells and attach more strongly to the seafloor, making them harder to eat.

But the sharks attacked urchins from their spiny side, showing little regard for their sharp defences. This approach differs from other predators, such as lobsters and wrasses, which often turn urchins over and attack them methodically from their more vulnerable underside.

In fact, some sharks were so eager to eat urchins, they started feeding before the cameras turned on at sunset. This meant we had to film by hand.

A complex food web

Our experiment showed the effect of lobsters on urchins in the wild is less than previously thought. This may explain why efforts to encourage lobster numbers have not helped control urchin numbers.

We also revealed a little-considered urchin predator: sharks.

Lobsters are capable but hesitant predators, whereas sharks seem eager to eat urchins. And crested horn sharks are an abundant, hardy species that is not actively fished.

When interpreting these findings, however, a few caveats must be noted.

First, sharks (and lobsters) are not the only animals to prey on urchins. Other predators include bony fishes, and more are likely to be identified in future.

Second, other factors can control urchin numbers, such as storm damage and the influx of fresh water.

And finally, it is unsurprising that we found a key predator when we intentionally searched for it by laying out food. Tethering urchins creates an artificial environment. We don't know if the results would be replicated in the wild.

And even though we now know some shark species eat sea urchins, we don't yet know if they can control urchins’ numbers.

But our research does confirm predators capable of handling large urchins may be more widespread than previously thought.

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.

Visitors at a national park in India have captured once-in-a-lifetime footage of a tigress and her three cubs dining on the carcass of a crocodile, which they ambushed and killed as a family.

Pictures taken on Monday (April 15) show the feline family of four lying on the banks of a pond in Ranthambore National Park, in the northwestern state of Rajasthan, as they take turns feasting on the spoils of a very fruitful hunt. 

This isn't the first time the mother — a 6-year-old Bengal tigress (Panthera tigris tigris) named Riddhi — has gone after a crocodile, but it is her first documented success. 

"The footage captured the majestic tigress and her offspring in a rare moment of triumph," park representatives wrote in a statement. "Riddhi's prowess solidifies her status as the reigning queen of Ranthambore."

Related: Is the Javan tiger back from extinction? New study ignites controversy. 

Before Riddhi, her grandmother Machli was the park's resident "crocodile killer," according to the statement. Machli died in 2016 at the age of 19, but she lives on in the memory of spectators who saw her overpower and slay a 14-foot-long (4.3 meters) crocodile after a long battle.

Tigers don't often go after crocodiles, preferring to attack prey — including pigs, deer, elephant calves and leopards — on land, according to staff at Bandhavgarh National Park in India. 

But the big cats are mighty swimmers, so if a croc happens to be basking near the water's edge, where crocodiles are more vulnerable than in the water, tigers might take a chance. A tiger can eat more than 80 pounds (36 kilograms) of meat in one sitting, according to the WWF.

Riddhi and her three cubs, which were born in spring 2023, appeared unscathed from the fight. "The crocodile hunting thing is in their bloodline it seems," Parveen Kaswan, from the Indian Forest Service, wrote in a post resharing the video on the social platform X. 

Dinosaurs often steal the limelight when it comes to fossils, but other prehistoric critters are just as deserving of our attention. As 2023 comes to a close, it's time to look back on some of the most  jaw-dropping fossil discoveries that weren't all about T. rex. From a fish with eyes too big for its stomach to the largest ever fossilized flower and mysterious marine fossils that glow gold, here's our pick of non-dino fossils that blew our socks off in 2023.

Largest penguin to walk Earth

In February, scientists described fossils belonging to the largest known species of penguins — Kumimanu fordycei, which weighed a whopping 340 pounds (154 kilograms). These colossal penguins glided through the ocean around what is now New Zealand more than 50 million years ago, bones discovered inside beach boulders in North Otago on the country's South Island revealed.

Researchers estimated the weight of K. fordycei based on the size and density of these bones compared with those of living penguins. The fossilized remains of eight other penguin specimens were also uncovered inside the boulders, including those of the newfound species Petradyptes stonehousei and a known species of giant penguin, K. biceae.

Giant penguins likely disappeared around 27 million years ago, when they were outcompeted by marine mammals similar in size, experts told Live Science.

Tiny penguin skulls

In June, researchers identified two tiny skull fossils from New Zealand's North Island as belonging to a never-before-seen extinct species, which they named Wilson's little penguin (Eudyptula wilsonae). The skulls, one from an adult and the other from a juvenile, were remarkably similar to those of the smallest living species of penguin today — the little penguin (Eudyptula minor).

Researchers don't know exactly how small the extinct birds were, but little penguins grow to a maximum size of 13.5 inches (35 centimeters) and weigh around 2 pounds (0.9 kg), which may be in the ballpark.

Related: Ancient skeletons of largest-ever marsupial unearthed in Australia

Fossilized flower mystery solved

In January, scientists finally got to the bottom of a 150-year-old mystery. They discovered that a flower entombed in a hunk of amber and discovered in the Baltic forests of Northern Europe in 1872 is a newfound species named Symplocos kowalewskii that dates to the late Eocene epoch (roughly 38 million to 33.9 million years ago).

The specimen, which measures about 1 inch (2.8 cm) wide, is the largest fossilized flower ever recorded and is three times the size of the next-biggest amber-encased bloom. 

Trilobites' hidden third eye

Scientists examining a fossilized trilobite specimen — an extinct marine arthropod that lived during the Paleozoic Era (541 million to 252 million years ago) — discovered that these prehistoric creatures didn't have just a pair of compound eyes, as previously thought, but also sported a third eye in the middle of their forehead.

The trilobite specimen was missing a part of its head, which gave researchers a glimpse under a layer of shell that becomes opaque during the fossilization process and obscures the structures beneath. Hidden median eyes are common among arthropods living today.

Baby turtles mistaken for plants

A re-examination of two ancient "plant" fossils discovered in Colombia 50 years ago revealed they are actually the remains of hatchling turtles from the dinosaur age. The 2-inch-long (5 cm), leaf-shaped fossils fooled their finder, who originally placed them within a group of plants that thrived during the Late Devonian (419.2 million to 358.9 million years ago) and the Permian (298.9 million to 251.9 million years ago). 

In December, it turned out the fossils were extremely rare imprints of the upper shells of baby turtles dating back to the Aptian age (125 million to 113 million years ago) of the Cretaceous (145 million to 66 million years ago).

It's possible the hatchlings were members of the oldest sea turtles on record — Desmatochelys padillai — but researchers would need a complete skeleton to confirm this.

Related: Flesh-eating 'killer' lampreys that lived 160 million years ago unearthed in China

Beheaded in action

A fossil from the Middle Triassic (247 million to 237 million years ago), which was discovered on the border between Italy and Switzerland, showed bone breaks and tooth marks consistent with a brutal beheading. The victim, a giant marine reptile called Tanystropheus hydroides with a neck three times as long as its torso, had its head torn off in one clean bite by an even deadlier creature that likely swooped down from above, experts said.

It's unclear which predator could have killed the 20-foot-long (6 meters) reptile, but researchers narrowed down a list of suspects by measuring the distance between the tooth marks. Potential candidates include the 18-foot-long (5.5 m) ichthyosaur Cymbospondylus buchseri; an enormous reptile measuring up to 23 feet (7 m) long called Nothosaurus giganteus; and Helveticosaurus zollingeri — an enigmatic, 12-foot-long (3.6 m) predator.

Slasher dolphin with jutting teeth

In June, researchers identified a stunningly preserved dolphin skull as a newfound species that lived 25 million years ago during the Oligocene period (34 million to 23 million years ago). The fossil, which was first discovered buried in a cliff face in 1998 and was being held in a museum collection in New Zealand, was recently named Nihohae matakoi, from Maori words meaning "slashing teeth, face sharp."

The skull was around 2 feet (60 cm) long and sported long teeth that stuck out almost horizontally from what would have been the snout. These spade-like teeth were probably unsuited to catching fish, the researchers said, but the creature may have thrashed at its prey to stun it before slurping it up. It's also possible the dolphin's jutting teeth served a sexual or social purpose.

Prehistoric fish's last supper

An intriguing fossil found in a museum drawer captured the moment a prehistoric fish swallowed an ammonite — an extinct marine mollusk — and choked to death on it. The ammonite remained intact inside the fish's body and became imprinted in rocks, lodged up against the predator's spine. The pair likely died together about 180 million years ago, during the Jurassic period (201 million to 145 million years ago).

The fossil was discovered in 1977 near Stuttgart, in southwest Germany, but researchers initially stored it away, as they thought the pairing of the fossilized fish and ammonite was a coincidence. Another look recently revealed the ammonite was inside the fish and likely caused its death due to the mollusk's size — equivalent to a human swallowing a dinner plate.

Related: Low water levels in Lake Powell reveal 'extremely rare' fossils from extinct Jurassic mammal relative

Mysterious golden fossils

Shimmering fossils of marine animals from Germany's Posidonia Shale were long thought to glow gold thanks to a mineral called pyrite, but they turned out to contain very little of it. Instead, researchers traced the fossils' golden glimmer to phosphate minerals with yellow calcite. Unlike pyrite, phosphate minerals need oxygen to form, which revealed new information about the fossilization process in the region.

Fossils from the Posidonia Shale — which include ammonites, bivalves and crustaceans from the Jurassic period — are found in what researchers once thought was a completely oxygen-depleted environment. The discovery of phosphate minerals in the grooves means a burst of oxygen must have reached them at some point, turning the fossils into what looks like gold.

Mystery of prehistoric shrimp's supper solved

A shrimp-like Cambrian critter's choice of food has surprised scientists: It was thought to feed by piercing hard-shelled prey, but it turns out it likely hunted soft-bodied animals instead. In July, computer models of fossils dating to 500 million years ago suggested Anomalocaris canadensis, which was about the size of a house cat and boasted two spiky facial appendages, probably swam like a cuttlefish with its appendages outstretched to pincushion prey.

Contrary to what was previously thought, A. canadensis' appendages probably weren't robust enough to skewer trilobites — extinct marine arthropods with a tough exoskeleton. So the strange creature more likely feasted on squishy animals floating in the water column.

Fleeing vampire with luminous organs

A new analysis of fossils belonging to a group of mostly extinct, octopus-like creatures called vampyromorpha revealed a previously undescribed species with eight arms, sucker attachments like a vampire squid and glow-in-the-dark organs. 

The 3.2-inch-long (8 cm), bullet-shaped creature stalked Earth's oceans 165 million years ago and likely snatched prey using its arms. Researchers in France named it Vampyrofugiens atramentum — a combination of the Serbian word for vampire, "vampir," and the Latin word for fleeing, "fugiens" — meaning the fleeing vampire. 

An unusual, all-female assembly of great hammerhead sharks has been gathering in the tropical waters of French Polynesia every summer for over a decade, with numbers peaking around the full moon, scientists have discovered.

These critically endangered sharks convene during the austral summer, between December and March, around openings in two neighboring atolls — Rangiroa and Tikehau — in the Tuamotu archipelago. An atoll is a ring-shaped island or coral reef enclosing a lagoon that forms when land erodes and sinks below the ocean surface.

In the summers of 2020 and 2021, researchers recorded 54 female great hammerhead sharks (Sphyrna mokarran) and one whose sex could not be determined at the two atolls, which are 9 miles (15 kilometers) apart.

They noted that more than half of the sharks were seasonal residents, meaning they spent up to six days a month there, for up to five months. The findings were published Tuesday (Aug. 29) in the journal Frontiers in Marine Science.

Related: Critically endangered hammerhead shark found dead on US beach was pregnant with 40 pups

Female sharks in the vicinity of Rangiroa atoll mostly gathered in a spot called "hammerhead plateau" —  an area 150 to 200 feet (45 to 60 meters) deep, according to the study. "They were mainly sighted roving around the bottom of the plateau, independently from one another," the researchers wrote.

Great hammerhead sharks are a solitary species, so the high number of females sighted at the same time around Rangiroa and Tikehau atolls indicates the area is an aggregation site, according to the study. The sharks likely have no relationship to each other but are drawn there by external factors that appear to be linked to the lunar cycle and the presence of ocellated eagle rays (Aetobatus ocellatus), the study found.

The number of sharks peaked in the days shortly before and after a full moon during both summers — perhaps because the increased moonlight enhanced their ability to hunt around the atolls at night, the researchers suggested. The sharks may also have responded to changes in Earth's geomagnetic field as the moon waxes and wanes, they posited.

Large gatherings of great hammerheads in the area coincided with high numbers of ocellate eagle rays entering the lagoons to reproduce. Sharks prey on these rays, whose mating season is "a predictable event that sharks could try to intercept," the researchers wrote.

Increased water temperature after the winter months may also lure sharks to the Tuamotu archipelago, the scientists added.

The researchers compared their observations with long-term data collected on the atolls, which revealed that some sharks have been returning every summer for 12 years. The team identified an additional 30 male and female sharks from these records and found that males were primarily sighted from August to October, rather than during the summer.

Segregation between males and females has previously been reported for scalloped hammerhead sharks (Sphyrna lewini), the researchers noted, but not for great hammerheads. The researchers' findings suggest that males remain at a distance from the sites occupied by females during the austral summer, which could be linked to their breeding period.

"Lagoons and their protected warm-shallow-coastal waters are known to serve as nursery areas for various shark species," the researchers wrote. While they could not confirm this in the new study, further investigation is underway to determine whether Rangiroa and Tikehau atolls provide nursery grounds for great hammerhead sharks, they added.

A black bear has been caught napping in an unlikely spot: the nest of a bald eagle. Researchers came across the sleeping bear while surveying eagle nests on a military base in Alaska. 

Black bears (Ursus americanus) are known to occasionally take advantage of eagles' architectural work — and these invasions spell trouble for the birds and their young, according to the U.S. Fish and Wildlife Service (FWS).

"In the past, a few eagle nests have been raided by black bears with predictably bad results for the nesting eagles," FWS staff wrote in a Facebook post on July 21, adding that these incidents often result in young birds going missing.

Bears occasionally eat eagles' eggs and nestlings, said Stephen B. Lewis, a FWS wildlife biologist who led the nest surveys on Joint Base Elmendorf-Richardson (JBER) military base in southern Alaska. "It's hard to say how much bears invade eagle nests because we don't (can't) spend that much time monitoring to see it happen or have cameras to witness it," Lewis told Live Science in an email.

Related: Grizzly bear believed to have killed woman on Buttermilk Trail near Yellowstone National Park 

During a helicopter survey in May, researchers spotted a female bald eagle (Haliaeetus leucocephalus) incubating an egg on the nest later occupied by the sleepy bear. A week later, the egg had been left out in the cold while both the female eagle and her mate busied themselves nearby.

"It wasn't clear if the nesting attempt had failed or if the female was just taking a break from incubating," Lewis said, adding that males would usually take over from females to keep the egg toasty, especially in cool places like Alaska. For that reason, Lewis suspects the nest "failed" in the spring, long before the bear crawled into it.

Bald eagles are Alaska's largest resident birds of prey and have wingspans of around 7.5 feet (2.3 meters), according to the ADFG. These raptors build the largest nests of any North American bird, with some nests measuring 8 feet (2.4 m) across and weighing more than two tons (1.8 metric tons).

These huge nests may also provide safe resting places for black bears that usually make "beds" on very steep slopes where other animals can't disturb them, Lewis said. "This nest isn't that far off from such a bear bed. It could have just happened to climb the tree and decided to take a nap."

Fishy smells wafting down from the nest may also have lured the bear. Eagle nests can be "rather smelly," because the fish adults catch for their young sometimes go uneaten. "Often that food isn't entirely consumed and ends up getting stomped into the nest or laying on the side and rotting," Lewis said. "Bears have incredible senses of smell so perhaps a bear is attracted to the smelly nest."

Bald eagles were listed as an endangered species across the U.S. in 1978, after their numbers plummeted due to habitat destruction, illegal shooting, pesticides and poisoning, according to the Alaska Department of Fish and Game (ADFG). Stronger protections have allowed populations to recover and monitoring is ongoing to assess the impact of other human disturbances, such as tourism and oil spills. 

About 3 million years ago, giant petrels terrorized the skies and seas of the Southern Hemisphere with their deadly hooked bills and piercing eyes, a new study on a previously unknown bird species finds.

The discovery — based on a well-preserved skull and weathered humerus (upper wing bone) of the ancient predator from New Zealand's North Island — marks the only extinct giant petrel species on record, the researchers reported in a study published Jan. 30 in the journal Taxonomy.

The Tangahoe Formation, where they found the remains, "continues to provide outstanding seabird fossils and is becoming an important piece of the puzzle to understand the evolution and biogeography of seabirds in New Zealand and beyond," the team wrote in the study.

Amateur fossil hunter Alastair Johnson discovered the skull in 2017 and found the humerus two years later in a different spot along the rock formation. The researchers named the newly described species Macronectes tinae, in honor of Johnson's late partner, Tina King. "This giant petrel skull was her favourite fossil, hence the homage," they noted in the study.

As the first distinct evidence of an extinct giant petrel species, M. tinae offers paleontologists insight into how its modern relatives evolved. Although the now-extinct M. tinae is part of the giant petrel genus (Macronectes), it was actually smaller than the modern species Macronectes giganteus and Macronectes halli, which also live in the Southern Hemisphere. 

Related: Monster bird fossils unearthed in Antarctica

The Southern giant petrel (M. giganteus) and Northern giant petrel (M. halli) can grow to about 3 feet (1 meter) long from beak to tail, with wingspans sometimes reaching more than 6 feet (1.8 m). Since scientists have limited fossil evidence of M. tinae, it's hard to know exactly how big the bird was, study co-author Rodrigo Salvador, a paleontologist at UiT, The Arctic University of Norway, told Live Science. But based on the fossils we do have, he estimates that M. tinae was about the size of the smallest giant petrels alive today. That would mean the bird had a wingspan of around 5 feet (1.5 meters) across — nothing to scoff at.

Size-wise, giant petrels are actually an anomaly — most other petrels are slightly smaller than ducks. That means M. tinae's smaller body size isn't surprising, Daniel Ksepka, a paleontologist at the Bruce Museum in Connecticut who wasn't involved in the new research, told Live Science. Because giant petrels are so much larger than the rest of their family, known as Procellariidae, it stands to reason that they've been growing over time, Ksepka said.

But giant petrels have another advantage over other petrels. Many petrel species can't walk well on land due to their skimpy little legs, so they fly around when hunting, skimming or diving into the ocean for food when they spot prey. Giant petrels, on the other hand, have strong legs and wide feet that allow them to walk on land to scavenge for carrion and hunt smaller animals. And they don't use their big beaks to politely poke at dead animals; they often really go to town in a carcass, covering themselves in blood and guts.

"They will not hesitate to put their entire face inside the seal and eat," Ksepka said.

It's possible that M. tinae also enjoyed a face full of blood and guts, based on the sinister-looking beak it sported, Ksepka said. And because none of the other petrel species do this, the authors had an artist depict the newfound species in all its brutishness, featuring M. tinae in a gory, seal-eating scene, Salvador said.

The Tangahoe Formation is typically made up of fine-grained sediment, which helped preserve a lot of fossils, including birds, mammals and invertebrates, Salvador said. But this rock layer may offer more than just a link to the past.

During the late Pliocene epoch (5.3 million to 2.5 million years ago), when these fossils were deposited, temperatures were a few degrees Celsius higher in New Zealand than they are today, Salvador said. And as climate change gets worse, that's a future we might be headed toward again.

"People might not really be caring too much about what giant petrels looked like 2 million or 3 million years ago," Ksepka said. "But understanding how different groups of animals were distributed in a warmer period of Earth history may help us predict how things could change in the future."

About 350 million years ago, long before the dinosaurs stalked the planet, a gigantic fish with deadly fangs hunted river waters on the ancient southern supercontinent Gondwana, a new study finds. 

This fish, measuring up to 9 feet (2.7 meters) long, is the largest bony fish on record from the Late Devonian (383 million to 359 million years ago) and was predatory, prompting researchers to call it Hyneria udlezinye, or the "one who consumes others," in IsiXhosa, a widely spoken Indigenous language in the region of South Africa where the bones were found.

"Picture a huge predatory fish, easily topping 2 meters [6.5 feet] in length and looking somewhat like a modern alligator gar but with a shorter face like the front end of a torpedo," study co-author Per Ahlberg, a professor in the Department of Organismal Biology at Uppsala University in Sweden, told Live Science. "The mouth contained rows of small teeth, but also pairs of large fangs which could probably reach 5 centimeters [2 inches] in the largest individuals."

Researchers discovered the first clues of the ancient fish's existence in 1995, when they unearthed a series of isolated fossilized scales at an excavation site called Waterloo Farm near Makhanda (formerly known as Grahamstown), in South Africa. Now, in a study published Wednesday (Feb. 22) in the journal PLOS One, the researchers have finally pieced together a skeleton of the newfound species of giant tristichopterid, a type of ancient bony fish.

"It's been a long journey ever since then, assembling the answer to where these scales came from," study co-author Robert Gess, a paleontologist and research associate at the Albany Museum and at Rhodes University in South Africa, told Live Science.

Related: 'Never seen anything like it': Impeccably preserved Jurassic fish fossils found on UK farm

The skeleton reveals that H. udlezinye was a voracious predator. "The fins are mainly towards the back of the body. This is an ecological characteristic of a lie-in-wait predator; it can put on a sudden spurt. Hyneria would have lurked in the dark shadows and waited for passing things," Gess said. "It's the one that consumed others."

The giant fish probably preyed on four-legged creatures known as tetrapods, the ancestral group that led to the human lineage. "The tristichopterids evolved into monsters that, in all likelihood, ate [our ancestors]," Ahlberg said.

Previous research identified another species of the same genus, H. lindae, at an excavation site in Pennsylvania, which was part of the supercontinent Euramerica during the Late Devonian.

The fossils from Waterloo Farm are the first to indicate that Hyneria lived in Gondwana. The new study also reveals that giant tristichopterids lived not just in the tropical regions of Gondwana, but across the continent and even in the polar circle.

Most tristichopterid fossils found to date have been excavated in Australia, skewing our perception of the distribution of these animals. Other regions which belonged to Gondwana, like Africa and South America, are less well researched.

"Because Australia was in the tropics, and because all the well-sampled sites from this period and from Gondwana happen to be in Australia, there was a feeling that these giant tristichopterids originated in what is now Australia — along the tropical coast of Gondwana," Gess said.

Now, for the first time, researchers have found the remains of a giant tristichopterid in what would have been a polar region at the time. "We have this guild of ginormous predatory fish and this is the only example we have from the polar regions," Ahlberg said.

Tristichopterids disappeared in a mass extinction event at the end of the Devonian, about 359 million years ago. They have no direct descendants today, but researchers think that a common ancestor with our ancestral lineage existed earlier in the Devonian. "Late Devonian tristichopterids are more our second cousins than our direct ancestors," Ahlberg said.

The body of a woman in Indonesia was recently discovered in the stomach of a massive, 22-foot-long (6.7 meters) python, which had killed and swallowed its victim whole. 

The woman, a 54-year-old grandmother named Jahrah, went missing in Jambi province on the island of Sumatra on Oct. 23, according to CNN Indonesia. Her family reported her missing when she did not return home that evening. A search party, which included her husband, was unable to locate her that night, though they found her sandals and several articles of clothing on the ground, The Guardian reported. 

The next day, locals spotted a gigantic python lurking near the spot where her discarded clothing had been found. Witnesses said that the snake had a suspiciously large stomach bulge,  BBC News reported. A group of villagers chased the python down and killed it. After they split open the snake's belly they discovered a body inside, which was identified as that of the missing woman, local police chief AKP S Harefa said in a statement, according to CNN Indonesia. 

Related: Jaw-dropping study reveals how pythons can devour super-size prey

Indonesia is home to a huge variety of pythons, including green tree pythons (Morelia viridis), amethystine pythons (Morelia amethistina), Sumatran short-tailed pythons (Python curtus), and reticulated pythons (Malayopython reticulatus), the world’s longest species of snake.While the snake that killed the woman was not identified, it was likely a reticulated python given its sheer size. Reticulated pythons can measure up to 28.5 feet (8.7 m) long and weigh as much as 320 pounds (145 kilograms), according to Zoo Atlanta in Georgia. Like all pythons, they kill and consume their prey by slowly squeezing it to death and then swallowing it whole. “In essence they can go as large as their prey goes,” Mary-Ruth Low, a former conservation and research officer from Mandai Wildlife Group, told BBC News.

Reticulated pythons have been known to occasionally consume people. In 2018, a similar attack in which an Indonesian woman was killed and eaten by a reticulated python, made international headlines. However, experts say that these instances are exceedingly rare — only the very largest snakes are big enough to take down a human, and we aren’t easy prey to swallow thanks to our broad shoulders, which can get stuck in a snake’s throat. 

Thankfully, most fully grown reticulated pythons stick to a diet of civets, birds, wild pigs and the occasional monkey, according to the Vanderbilt Museum in Long Island, New York.

How do mosquito larvae catch their prey? By using their heads. 

In attacks that are too swift to be seen with the naked eye, predatory aquatic larvae, which measure about 0.75 inch (2 centimeters) long, launch their heads toward their victims like tiny harpoons, high-speed film footage reveals. 

In a decades-long investigation, scientists filmed larvae in three mosquito species as they consumed their prey. The findings, published Oct. 4 in the journal Annals of the Entomological Society of America, revealed that two of those species — Toxorhynchites amboinensis and Psorophora ciliata — could launch their heads to snap up a target meal in about 15 milliseconds. And in a surprise twist, the researchers discovered that speedy prey nabbing also happened in Sabethes cyaneus, a mosquito species in which the larvae are primarily passive filter feeders.

"They were using their siphons to snag prey larvae and pull them into their gaping mouthparts," said lead study author Robert Hancock, a professor in the Department of Biology at the Metropolitan State University of Denver. "That was one of these, 'I can't believe this; this is amazing' kind of moments."

Related: Mosquito 'tongue' neurons ignite like fireworks at taste of human blood

Hancock first observed this blink-and-you'll-miss-it hunting prowess decades ago during a medical entomology class he attended as a grad student under study co-author Woody Foster, who's now a professor emeritus in the Department of Evolution, Ecology and Organismal Biology at The Ohio State University in Columbus. In that class, as T. amboinensis larvae responded to prey, students watched the larvae under a microscope — or at least they tried to.

"We all saw a blur; then we saw a captured larva being shoveled into the mouth of a predator. That's all we saw," Hancock told Live Science. The next step, which would take more than 20 years to realize, was finding out what the predators were doing and how they were doing it. 

Hancock and his co-authors began filming experiments with T. amboinensis and P. ciliata in the 1990s, using the fastest-available optical system: a 16-millimeter film camera that had been designed for the U.S. military to track missiles. Once the study authors adapted the camera to film through a microscope, they held prey larvae with jeweler's tweezers to temp the predators, ultimately capturing footage of the larvae at 340 frames per second (fps).

Most of the time, "the predators would make a little body movement when the prey was introduced to their environment," which would signal to the researchers that it was time to hit the button on the film camera, Hancock said. 

"Body arching and head twisting"

The scientists found that the larvae launched their heads using thrust from accumulated abdominal pressure, and bunches of tiny brushlike bristles around their heads spread like fans into "basket-like arrangements" that helped sweep prey toward the predators' gaping and sharp-toothed jaws, the study authors wrote. P. ciliata "typically struck in a straight-ahead (axial-linear) fashion," according to the study, while strikes by T. amboinensis "often involved a great deal of both body arching and head twisting." 

"All scientists get excited about their discoveries, but this kind of science — these visual discoveries — are special," Hancock said.

But T. amboinensis and P. ciliata larvae are active predators, and the scientists wondered if similar methods might be used by species that combined hunting with filter feeding. After funding dried up, the project was put on hold until 2020, when the researchers were finally able to revisit that question. This time, they used a high-definition video camera capable of shooting up to 4,352 fps, with which they recorded S. cyaneus larvae in specially designed "arenas" of death.

The predatory action they saw, in which the larvae used their tails to swiftly sweep prey into their waiting mouths, was also previously unknown; like the head-launching strikes, hunting with tail sweeps took about 15 milliseconds from start to finish and was "spectacular," Hancock said. Once S. cyaneus gripped its victim, the larvae's mandibles "opened and closed so that their serrated teeth tore into the prey," according to the study.

Future studies could explore how common harpoon-headed hunting and tail sweeping are across the mosquito lineage, by "getting my cameras on as many different kinds of mosquitoes as possible," Hancock said. "There's a much bigger story to be told."

If the giant, extinct shark megalodon had to pick a favorite meal, the winner would likely be sperm whales ... by a nose. 

In fact, sperm whale noses were popular snacks not only for megalodon but also for other ancient sharks that preyed on sperm whales, according to a new analysis of fossil whale skulls.

When scientists in Peru peered at a series of skulls belonging to extinct whales that lived during the latter part of the Miocene epoch (23 million to 5.3 million years ago), they found numerous bite marks left behind by multiple shark species, including the massive megalodon (Otodus megalodon) and sharks that are still around today, such as great white sharks (Carcharodon carcharias) and mako sharks (Isurus). 

In some cases, a number of shark species had fed on the skull of a single whale in "a series of consecutive scavenging events" that left the skull scarred by more than a dozen bites. What's more, the location of the bite marks told the scientists that the sharks were targeting the whales' foreheads and noses, likely so the predatory fish could feast on the fatty organs' generous stores of nutritious blubber and oil. 

Related: Giant shark, possibly a megalodon, feasted on this whale 15 million years ago

Sperm whales are the biggest toothed predators alive today. They are known for their bulky heads, and much of the space inside is taken up by enlarged nasal organs that the whales use for sound production, the scientists reported June 29 in the journal Proceedings of the Royal Society B: Biological Sciences. Two structures in this nasal network, the melon and the spermaceti, are rich in oils and fats. And bite marks in the Miocene whale skulls corresponded with the positions of these structures in modern sperm whales, the scientists discovered. 

"Many sharks were using these sperm whales as a fat repository," said lead study author Aldo Benites-Palomino, a doctoral candidate at the Paleontological Museum of the University of Zurich in Switzerland. "In a single specimen, I think that we have at least five or six species of sharks all biting the same region — which is insane," he told Live Science.

Three species of sperm whale swim the oceans today: the great sperm whale (Physeter macrocephalus), the pygmy sperm whale (Kogia breviceps) and the dwarf sperm whale (Kogia sima). But around 7 million years ago, there were at least seven sperm whale species, ranging from small-fry species in the Kogia and Scaphokogia genera that were no more than 13 feet (4 meters) long, to enormous creatures such as Livyatan, which measured up to 60 feet (18 m) long.

And trailing after those Miocene sperm whales were plenty of ravenous shark species, just waiting for an opportunity to eat the whales' faces.

For the study, the scientists analyzed sperm whale skulls in the collection of the Natural History Museum in Lima. The skulls had been collected from the Pisco Formation in southern Peru and dated to about 7 million years ago; during the Miocene, this coastal desert region was a hotspot for marine biodiversity, the researchers reported.

The team discovered patterns of bite marks in six skulls. Some had just a few bite marks, while others displayed up to 18 perforations clustered around the whales' faces. "It was clear to us something was happening — sharks were somehow predating on these animals and trying to feed on their noses," Benites-Palomino said.

Variations in size and shape of the bite marks suggested that multiple shark species were lining up to take a bite. Large bite marks with a little bit of serration were "typical megalodon," while deep slices that looked like they were made with a sharp knife "could be either mako or sand sharks," he explained. "And then, if you have something in the middle — a little shallower and the serration is irregular — these are mostly caused by members of the white shark lineage."

Modern sharks are known for eating many things (including songbirds, sea turtles and even humpback whale carcasses) but not sperm whales, according to the study. This raises questions about what may have driven these voracious predators to shift their diet away from their once-favorite meal: sperm whales' delicious noses.

"You start to imagine how this changed, why this changed, was there some implication in the environment," Benites-Palomino said. "More than actually answering questions, I think this is making me have more inquiries around all of these discoveries."

Originally published on Live Science.

Long portrayed in pop culture as scary beasts, real sharks are no Hollywood monsters. Sharks are a diverse group of mostly predatory fish. They do not have bones; their skeletons are made of a tissue called cartilage. Sharks traveled the seas long before the dinosaurs roamed Earth, and they play vital roles in the ecosystem. These marine creatures face far more dangers from humans than surfers or swimmers do from them.

5 fast facts about sharks

• The largest known great white shark was 20 feet (6 meters) long.
• Sharks sleep, but they may keep their eyes open while they do it.
• Sharks can learn to solve puzzles by watching other sharks.
• Different shark species swallow their food whole, tear it apart with razor-sharp teeth, or grind it down with flat chompers.
• You're more likely to be killed by lightning than by a shark.

Everything you need to know about sharks

Shark pictures

Further reading

Watch director Eli Roth's "Fin" documentary on Discovery+. See the low risk of shark attacks put in terms of other rare risks, like getting struck by lightning, from the Florida Museum. Follow great white shark activity online with the Atlantic White Shark Conservancy Sharktivity app. Learn how shark teeth were mistaken for dragon tongues in the Middle Ages, along with other odd shark facts, from Smithsonian Magazine.

Discover more about sharks

—Sharks are older than the dinosaurs. What's the secret to their success?

—Angular roughshark: The pig-faced shark that grunts when captured

—Stupendous sharks: The largest, smallest and strangest sharks in the world

Shark quiz

In the waters off of South Africa, a killer whale killing spree is raging.

Since 2017, a pair of male orcas (Orcinus orca) have slaughtered at least eight great white sharks (Carcharodon carcharias) near the Gansbaai coast, tearing the fearsome fish apart and eating their livers in all but one case. Some of the sharks — which scientists periodically find dead and shredded on nearby beaches — were even missing their hearts.

Such grisly displays aren't that unusual for orcas, which have been observed killing everything from tiny fish to burly sharks, sea lions and even blue whales. But rarely have the violent escapades of two individual whales had such a clear and immediate impact on their habitat, say the authors of a new study published Wednesday (June 29) in the African Journal of Marine Science.

According to the researchers, great white shark sightings have dropped dramatically in the area since the two serial killer cetaceans began their spree five years ago. Using a combination of long-term sightings and tagging data, the researchers found that dozens of sharks have been actively avoiding regions of the Gansbaai coast when the orcas are nearby. Tagged sharks sometimes disappeared for weeks or months at a time, abandoning territory that, historically, has been dominated by great whites.

"What we seem to be witnessing though is a large-scale avoidance strategy, mirroring what we see used by wild dogs in the Serengeti in Tanzania, in response to increased lion presence," lead study author Alison Towner, a senior biologist studying white sharks at the Dyer Island Conservation Trust in South Africa, said in a statement. "The more the orcas frequent these sites, the longer the great white sharks stay away."

Serial killer whales

Gansbaai is located about 75 miles (120 km) east of Cape Town. According to the study authors, a year-round great white shark presence in the area has made Gansbaai a popular tourist destination for shark watchers.

Reaching up to 16 feet (4.9 meters) in length and sporting several rows of up to 300 serrated, knife-like teeth, great whites are among the top predators in the water. But beginning in 2015, the sharks of Gansbaai met their match when a pair of mature male orcas descended on the coast.

Like cartoon criminals, the orcas were easily identifiable by their battle scars; one whale's dorsal fin had collapsed to the right, while the other's bent to the left. These features inspired local whale watchers to nickname the orcas Port and Starboard. Nearly as soon as whale watchers spotted the duo at Gansbaai, a great white shark washed up dead on the beach.

Between 2016 and 2017, five more white sharks were found dead — four of them with their bodies torn open and their livers ripped out. (Unlike bony fishes, sharks have a very large, fatty liver, which could provide a lot of energy and nutrition to attackers, Live Science previously reported). Each shark's death corresponded with sightings of Port and Starboard in the area. While their official kill count is eight,, more undiscovered shark carcasses have likely been lost to the sea.

In the six months following the first shark's death, daily shark sightings at Gansbaai plummeted from over six sightings per day to just one. Detections of sharks tagged with electronic transmitters also dropped. Prior to the attacks in 2017, between three and eight tagged sharks were detected in the area each day. For several months after, that number dropped to zero. Transmitter data showed that individual sharks sometimes swam hundreds of miles away from Gansbaai within a few days of an orca attack. In some cases, sharks stayed away for six months or more before returning.

This mass shark migration has had downstream effects on the local ecosystem, the researchers said. Most noticeably, a new mid-level predator called the bronze whaler shark (Carcharhinus brachyurus) has moved into the area to take over the niche that great whites previously filled. These sharks are often preyed upon by great whites, but with the big guys gone, bronze whaler sightings have increased significantly, the researchers found. This shift could ripple down the entire food chain, putting pressure on the whole ecosystem, the team added.

What's driving this killer whale spree in the first place? Fierce as they are, orcas don't typically prey on great white sharks, the researchers said — however, scientists have observed a rare flat-toothed sub-species of killer whale in South Africa that seems to specialize in hunting sharks. It's possible that Port and Starboard belong to this group, the team wrote. The sudden appearance of orcas at Gansbaai could be "related to a decline in prey populations, including fishes and sharks, causing changes in their distribution pattern," Towner said.

Further observations of the whales and sharks of Gansbaai are needed to fully solve this ocean murder mystery.

Megalodon (Otodus megalodon), one of the largest sharks to have ever lived, mysteriously vanished from the fossil record about 3.6 million years ago. Now, scientists suspect that the massive predator may have been driven to extinction by a rival marine species: great white sharks.

Prior research hypothesized that megalodon's decline may have coincided with the rise of great white sharks (Carcharodon carcharias), which likely hunted the same prey as their larger cousin, Jeremy McCormack, a geoscientist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and lead author of a new study about these prehistoric competitors, told Live Science in an email. Supporting this explanation for megalodon's relatively sudden disappearance were bite marks on the bones of other marine animals; these scars were made by both great whites and megalodon, suggesting that the two species may have competed for similar food resources. 

But these bite marks provided only a single snapshot of isolated interactions between predator and prey, McCormack said. To find out if great white sharks truly starved megalodon out of existence would require a more complete survey of both species' diets. 

For that, McCormack and his colleagues looked for clues in the animals' teeth; they looked not at tooth size or shape but rather at the amount of zinc that was present in each tooth. 

Related: What caused this massive megalodon's mega-toothache?

"Zinc is essential for organisms, as it plays an important role in a wide range of biological processes," McCormack said. Most importantly, zinc is incorporated into teeth as they grow. When a predator hunts, it ingests minerals and nutrients from its prey. One of those minerals is zinc, which comes in two isotopes (variations of the same element with a different number of neutrons). One zinc isotope is heavier and the other is lighter. Other researchers who previously analyzed animal teeth found that  ratios  of heavier to lighter zinc isotopes  in an animal's teeth could reveal that animal's position  in a food chain. If teeth contain more of the lighter isotope and less of the heavier isotope, the animal is closer to the top of the food chain in its ecosystem. But if the teeth hold more of the heavier isotope, chances are that the animal is a bottom-feeder. These zinc ratios enable scientists to determine an ancient animal's trophic position with a great deal of accuracy. 

McCormack and his colleagues examined teeth from 20 modern species of fish, including sharks from wild and aquarium populations. The researchers then compared the zinc ratios in the teeth of the living fish with those in teeth from ancient great whites and extinct megalodon. 

Great white sharks evolved about 4 million years ago, overlapping with megalodon for approximately 400,000 years, Live Science previously reported. At first, megalodon and great whites occupied separate niches and didn't compete with one another. But the scientists discovered that zinc ratios in fossil shark teeth documented a shift in that relationship, one that caused them to directly bump fins with one another. In the early Pliocene, or about 5.3 million years ago, some populations of great whites began to shift their position up on the food chain to become top predators themselves, invading megalodon's territory. This would have meant that the two species were then forced to share resources, with the more efficient hunter driving the less efficient one out of existence. 

In addition to competition with great whites, "the extinction of Otodus megalodon could have been caused by multiple, compounding environmental and ecological factors," the researchers wrote in the study. These factors could have included climate change and the collapse of available food resources in general, in addition to  being out-sharked by great whites. 

This study was published May 31 in the journal Nature Communications.

Originally published on Live Science.

Anglerfish are one of the most frightening creatures to swim in the ocean. If its bucket-sized mouth bearing razor-sharp teeth, tiny frosted eyes and spiky fines weren’t scary enough, add its ability to lure its prey with glowing head lanterns and the anglerfish becomes the stuff of nightmares. 

In 1833, an almost perfectly spherical fish washed ashore in Greenland and was taken to zoologist Johannes Christopher Hagemann Reinhardt in Copenhagen, Denmark. This fish – later known as the footballfish, Himantolophus groenlandicus, or the man-gobbler – was the first anglerfish known to science, wrote Ted Pietsch, a systematist and evolutionary biologist, in his book "Oceanic Anglerfishes" (University of California Press, 2009). 

Today, there are about 170 known species in 12 families of deep-sea anglerfish, and a "huge diversity" within those families, Mackenzie Gerringer, a professor of biology at SUNY Geneseo in New York who specializes in deep-sea fish told Live Science. 

Common names for anglerfish hint at some of the wild forms they can take – snaggletooth sea devil, wolf trap and pugnacious dreamer (also known as the tyrannical toad), to name just a few. They sport a fantastic range of shapes and textures; some are squat and round (Melanocetus johnsonii), while others are flat and huge-snouted (Thaumatichthys binghami) or covered in whiskery filaments (Caulophryne jordani). But while these fish are found all over the world, they are fairly elusive, solitary – par for the course for a fish that lives 1,000 to 16,400 feet (300 to 5,000 meters) below the surface. As a result, new species are still being discovered, each more strange than the last.

But no matter what it looks like, any deep-sea anglerfish is a small ocean-dwelling creature’s worst nightmare.

Luring in the unlucky

Anglerfish are named for the glowing lure they use to attract the fish and crustaceans they eat. These fearsome hunters lurk quietly in the depths of the ocean. They’re ambush predators, Gerringer said, floating and waiting in the dark until prey comes near. Then, they use their built-in fishing rod to lure in the unlucky animal, wiggling, hiding and revealing their lure to tempt potential prey until they are close enough to be sucked up. 

This feeding strategy explains anglerfish’s bodies: Because they don’t actively hunt, they haven’t evolved to be fast swimmers, which is why many are blobby, non-hydrodynamic shapes. National Geographic even called anglerfish "quite possibly the ugliest animal on the planet" (though the blobfish would like a word).

In the deep ocean, meals are few and far between. Pietsch wrote in Oceanic Anglerfishes that most anglerfish stomachs that have been examined are empty. So when an anglerfish does come across a meal, they make it last. Anglerfish mouths are often the biggest part of their bodies, and if a meal “can fit in the mouth, it can fit in the body,” Gerringer said. Many anglerfish can stretch their stomachs to double their original size. 

"They’ll end up with a bubble belly," she told Live Science. "Sometimes they’re caught and they have whole fish in their stomachs. If you touch the stomachs, it’s quite squishy, for lack of a better term." 

But don’t worry too much about these deep-sea horrors: They’re far too small to hurt a human, making their oversized teeth and misshapen bodies… kinda cute? While some anglerfish can grow up to three or four feet (0.9 to 1.2 m) long (like Ceratias holboelli), the average size of an adult is 6 inches (16 centimeters) long — a little smaller than a volleyball.

Glow up

Anglerfish lures glow in the deep ocean, at least half a mile (0.8 kilometers) below the sunlit surface, thanks to luminescent bacteria that take root in the fish’s lure. The lure, also called an "esca," has a pore on the end that is designed to host these bacteria, many of which can’t live anywhere else, and many of which are unique to that species of anglerfish.

But where do the glowing bacteria come from? Anglerfish are born deep in the ocean as tiny, transparent larvae and float alone to the surface to feed and develop into their adult forms. They don’t grow an esca until later in life, so they have nowhere to nurture their bacterial colonies from birth, Gerringer said. "It’s a big research question right now," she added. 

Of the anglerfish esca bacteria that have been studied, none have been found living freely in seawater, Pietsch wrote in his book, meaning that it’s unlikely the fish pick their glowing buddies up from their environment. 

Do they live on an anglerfish’s skin until the esca develops? Do they, as one study in the journal eLife suggested in 2019, come from adult anglerfish spewing bacteria into the water, to be immediately picked up by younger fish? "There’s a lot of open questions," Gerringer said.

The diverse anglerfish don’t stop at a simple glowing lure, though. Some species, such as Phyllorhinichthys balushkini, have elaborate light guides protruding from their bodies, like biological fiber optic cables. Others, like Cryptopsaras couesii, have glowing spots on their backs called caruncles. Some, like members of the Thaumatichthys genus, have lures on the roofs of their mouths.

Snapping the trap with anglerfish teeth

Once an anglerfish has lured in its prey, the fish has every incentive to keep it. According to Karly Cohen, a PhD candidate studying the biomechanics of fish teeth at the University of Washington, most animals sport teeth that are firmly attached to their jaws – with anglerfish as a notable exception. Some of their fang-like teeth are "depressable," or able to fold in under pressure. "It could be that the teeth are working similar to a spike guard in a parking garage," Cohen told Live Science. "It's easy for prey to go in the mouth, but hard for them to get out."

To understand anglerfish teeth, Cohen uses a technique called histology. She embeds teeth into resin blocks, and then slices that block microscopically thin. That way, she and her colleagues can stain and identify specific tissues (enamel, pulp and ligaments, for example) to determine how those teeth developed. 

But a newer technique allows Cohen to get an even better look at one anglerfish’s jawful of fangs. Using a CT scan, Cohen virtually sliced the entire fish into sections that could then be reassembled digitally and viewed from any angle.

Unlike us, Cohen said, "fish put teeth everywhere," and often in places that are hard to spot while just looking at a specimen. With a 3D rendering of a tiny (but ferocious) fish like Melanocetus johnsonii, just 2 inches (5 cm) in length, Cohen and her colleagues can make better models of these elusive animals’ bite.

The worst sex on Earth

Many species of deep-sea anglerfish have one of the weirdest reproduction strategies on the planet. Males are parasites – and we don’t mean that metaphorically. 

In many deep-sea anglerfish species, the males are often 10 times smaller than females, said Gerringer, and they have no function other than to reproduce. They use highly developed scent organs to track down females. When they find one, they bite into her: According to Cohen, some male anglerfish develop specialized hooked teeth in front of their mouth specifically for getting a grip. (Cohen is researching whether these teeth are true teeth or a kind of proto-tooth called odontodes.) Then, they release an enzyme that dissolves the skin of their mouth, fusing with the female’s body. The males become completely dependent on the female for sustenance; their circulatory systems merge so that they’re sharing the same blood, and essentially the males become a living pair of testicles. 

"Since there’s a low probability to run into each other in the ocean, you want to be able to stick together when you find a mate. And they take this to the extreme," Gerringer said.

Females don’t stop collecting partners when they have one male fused to them: The record, Gerringer said, is 12 males to one female.

The fusing that takes place is similar to an organ transplantation, since the males essentially become a part of the female’s body. Research published in the journal Science in 2020 found out how anglerfish manage this feat: They lack genes to produce most of the molecules that would attack foreign tissue – plus they have few or no T-cells and antibodies. This lack of an immune system would likely kill a human, study co-author Dr. Thomas Boehm said in a press release describing the study, but it’s exactly what anglerfish need to carry out their weird sexual parasitism-based reproduction.

Changes in the deep ocean

Not many creatures in the ocean eat anglerfish (although some have been found in the stomachs of other deep-sea predators, such as the Antarctic toothfish, Dissostichus mawsoni), and since anglerfish make their home in deep water, they are not really targeted or accidentally caught by humans. So you might think that the anglerfish population is perfectly safe. 

However, that’s not the case. "We think of deep ocean communities as being out of sight, out of mind, but they’re closely connected to the rest of the ocean ecosystem," Gerringer said. A recent opinion article published in the journal Proceedings of the National Academy of Sciences argued that deep-sea mining in search of increasingly scarce rare earth minerals could become a threat to the ocean. The emerging technology, as reported by Nature, could shoot sediments and mining waste from the seafloor up into the water column where it could remain in the mid-ocean. That habitat is home not just to anglerfish but tens of thousands of other species, according to a report in Science Daily. That muck could clog up gills, starve filter-feeders and change the way light – and the allure of an anglerfish’s esca – travels in the ocean.

Climate change is a threat too, Gerringer said, by increasing ocean stratification. This means that water isn’t mixing from the surface down into the deep ocean as much as it used to, so less oxygen is making its way down to the depths. Ultimately, though, anglerfish are still so mysterious that for many, "we just don’t know" how humans might affect them, Gerringer said – or even what their baselines are.

But technology is improving all the time. In 2014, the Monterey Bay Aquarium Research Institute captured the first ever video of a “black seadevil” anglerfish and then brought it to the surface for a closer look, expecting that the fish wouldn’t live long at sea level. But in 2018, National Geographic reported how scientists’ ability to safely bring live deepwater fish to the surface is evolving. Someday soon, thanks to developments like these and the continued exploration of the deep ocean, we may know more about these bizarre, mysterious creatures.

Additional resources

Explore the deep-sea anglerfish family on the Tree of Life. For more facts about the ocean’s “twilight zone” from the Woods Hole Oceanographic Institute.

Bibliography

• Theodore W. Pietsch, "Oceanic Anglerfishes: Extraordinary Diversity in the Deep Sea", University of California Press, 2009. 
• Census of Mariner Life, "How Many Fish In The Sea? Census Of Marine Life Launches First Report", Science Daily, October 2003. 
• Olive Heffernan, "Seabed mining is coming — bringing mineral riches and fears of epic extinctions", Nature, July 2019. 
• Jefferey C. Drazen, "Midwater ecosystems must be considered when evaluating environmental risks of deep-sea mining", PNAS, July 2020. 
• Jeremy Swann, "The immunogenetics of sexual parasitism", Science, July 2020. 
• University of Washington, "Deep-sea anglerfishes have evolved a new type of immune system", July 2020. 
• National Geographic, "Anglerfish", accessed April 2022. 

Geckos that are typically placid and mild-mannered become violent, head-shaking "berserkers" when subduing a scorpion meal, new research reveals.

When a western banded gecko (Coleonyx variegatus) bites down on its scorpion prey, it repeatedly whips its head from side to side, slamming the scorpion into the ground over and over again. The geckos are "the least intimidating animal you've probably ever met," lead author Malachi Whitford, who conducted the research as part of his doctoral degree in ecology at San Diego State University (SDSU), said in a statement. "But then they see a scorpion — they go like, berserker mode."

This violent approach may lend the gecko some protection from the venomous stingers of the scorpions, according to the new study.

Animals such as roadrunners, crocodiles and some mammalian carnivores are known to immobilize their prey through shaking, but this is the first detailed description of banded geckos shaking scorpions, Whitford told Live Science in an email. 

Related: 6 crazy skills that prove geckos are amazing

Western banded geckos live in arid parts of western North America and measure about 4 to 6 inches (10 to 15 centimeters) long. The reptiles mostly eat insects but occasionally snack on dune scorpions (Smeringurus mesaensis).

Study co-author and SDSU biology professor (and Whitford's graduate advisor) Rulon Clark first observed the scorpion-smacking geckos in the 1990s, when he was an undergraduate research assistant working at a desert site near Yuma, Arizona. Whitford, now a professor of environmental science at Clovis Community College in Fresno, California, said that when the researchers decided to investigate this further, "it became very apparent that the geckos would readily perform the shaking behavior when presented with a scorpion." 

Once the shaking was done, the geckos would quickly swallow the scorpions in a few gulps, Whitford said. "The whole process was over in just a few seconds," he added.

The scientists filmed the geckos at 1,200 frames per second as the animals stalked and caught scorpions and non-venomous prey. They conducted 21 trials in which nine geckos were given scorpions to eat, and 10 trials in which eight geckos ate non-scorpion prey. Using digital tracking technology, the scientists mapped the geckos' head movements frame-by-frame, measuring variables such as velocity and acceleration as the geckos shook scorpions back and forth more than a dozen times in just a few seconds. 

The geckos rotated their heads and bodies to and fro in a cyclical motion in order to smash the scorpions against the ground, the study found.

There are a few ways in which shaking scorpions could make them safer for the geckos to eat, the scientists said in the study. One possibility is that shaking immobilizes the scorpions; but only about 62% of the scorpions were immobile after being shaken.

Most of the geckos that were given scorpions — about 90% — were stung during their encounters, but it's possible that shaking the scorpions reduced the severity of their stings or prevented the scorpion from delivering a full payload of venom, according to the study. All the shaking and slamming could also be an attempt to fracture the scorpion's stinger.

"Given the speed and violence of shake-feeding, we suggest that geckos shake the scorpion to cause mass trauma and subsequent immobility or, potentially, to break the stinger and render the scorpion harmless," the researchers wrote.

More detailed observations of the geckos, using multiple camera angles and 3D modeling, could provide a clearer picture of how scorpions are affected by all that violent motion, the authors concluded.

"From our recordings, it was clear that the geckos were actively slamming the scorpions into the substrate. However, as we only have a top-down view of the shaking, we were unable to describe the forces being experienced by the scorpions," Whitford explained. "Ideally, the next step would be to study the shaking behavior using 3D videography."

The findings were published Jan. 5 in the Biological Journal of the Linnean Society.

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.

Greenland sharks (Somniosus microcephalus) are the longest-living animals with a backbone, and survive for up to hundreds of years in the deep, cold waters of the Arctic and North Atlantic oceans. Greenland sharks belong to a family called sleeper sharks, which move slowly and stealthily through the water. 

These sharks sneak up on live prey and scavenge a variety of dead animals, including other sharks, seals, drowned horses and polar bears. Greenland sharks rarely encounter humans and scientists still have much to learn about their lifestyles. 

How big are Greenland sharks?

Greenland sharks grow up to 24 feet (7.3 meters) long and weigh up to 2,645 pounds (1,200 kilograms), according to the St. Lawrence Shark Observatory (ORS). That's longer than great white sharks (Carcharodon carcharias), which are estimated to grow up to 20 feet (6 m) long. (Although unconfirmed reports suggest they can reach 23 feet (7 m) in length, according to the Florida Museum of Natural History.) 

Greenland sharks have cylindrical bodies covered in teeth-like scales, called dermal denticles. These specialized scales reduce drag and help the sharks move more silently through the water, according to the ORS. The sharks can be black, brown, gray or a mixture of all three colors, and they may have spots. 

A Greenland shark's mouth contains 48 to 52 teeth in its upper jaw and 50 to 52 teeth in its lower jaw. The upper teeth are pointed, to help the sharks hold on to larger food, while the lower teeth are wide and curved sideways so the sharks can carve out round chunks of flesh from prey by moving their head in a circular motion, according to the ORS. 

Are Greenland sharks blind?

Ocean parasites called Ommatokoita elongata can render Greenland sharks partially blind. Ommatokoita elongata attach themselves to the eyes of Greenland sharks and can grow up to 1 inch (2.5 centimetres) long, according to the Encyclopedia of Life. The eye parasite tends to live in just one of the shark's eyes so they usually don't go completely blind. Because the sharks rely more on their other senses to catch prey in the dark ocean waters, the parasites don't seem to affect the sharks much, according to the Florida Museum of Natural History. 

Related: Ancient Greenland shark reveals its age in eerie underwater video

How long do Greenland sharks live?

Greenland sharks' exact life span is unknown. A 2016 study published in the journal Science estimated that Greenland sharks have a maximum life span of at least 272 years, based on analysis of the sharks' eye tissue. Researchers estimated that the oldest Greenland shark in that study was about 392 years old, but the estimate had a margin of error of 120 years, which led to speculation that Greenland sharks could live to 512 years old. The estimated range hasn't been verified.

"It's important to keep in mind there's some uncertainty with this estimate," Julius Nielsen, co-author of the 2016 paper, previously told Live Science. "But even the lowest part of the age range — at least 272 years — still makes Greenland sharks the longest-living vertebrate known to science."

Greenland sharks live in the slow lane, with a top swimming speed of less than 1.8 mph (2.9 km/h). They also grow slowly at less than 0.4 inch (1 centimeter) per year and have slow metabolisms, according to the National Oceanic and Atmospheric Administration (NOAA). Scientists don't yet know how Greenland sharks live so long, but it may be linked to their slow way of life. 

Related: No, scientists haven't found a 512-year-old Greenland shark

Where do Greenland sharks live?

Greenland sharks live in the Arctic and North Atlantic oceans from North America to Greenland and from Portugal to the East Siberian Sea, according to the International Union for Conservation of Nature (IUCN). The sharks have a large range and can be found swimming from the surface down to depths of 8,684 feet (2,647 m), the IUCN says. 

Scientists still have much to learn about how Greenland sharks live and reproduce. Female Greenland sharks give birth to live young, called pups, that hatch from soft eggs that females carry inside their bodies. In a 2020 study published in the journal PLOS One, researchers estimated that Greenland sharks can give birth to between 200 and 324 pups per pregnancy, depending on the size of the shark. Greenland shark pups are just 14 to 18 inches (35 to 45 centimeters) long when they're born. However, little is known about how Greenland shark pups spend their early lives or how many survive to adulthood. 

What do Greenland sharks eat?

Greenland sharks have a varied diet that includes fish, other sharks, eels and marine mammals, such as seals. They have also been found with drowned land animals, including horses and reindeer, in their stomachs, and have been seen in large numbers at the sea surface, feeding together on the remains of whales and fish killed by commercial whaling and fishing, according to the University of Michigan's Animal Diversity Web (ADW). 

Scientists have even found a Greenland shark with the jaw of a young polar bear (Ursus maritimus) in its stomach, Reuters reported in 2008. The researchers were unsure how it got there; but most shark experts believed that the polar bear was likely already dead when the shark ate it, as live polar bears are too dangerous for the sharks to take on. Researchers also found some polar bear muscle tissue and skin in the stomach of another Greenland shark during a 2014 study published in the journal Polar Biology, and they concluded that the bear was likely scavenged rather than hunted. 

Does anything eat Greenland sharks?

Greenland sharks are near the top of the food chain, but sperm whales (Physeter macrocephalus) may hunt them. Chris Harvey-Clark, co-founder of the Greenland Shark and Elasmobranch Education and Research Group (GEERG, now the ORS), wrote in Capeia, an online science communication magazine, about recording a Greenland shark seemingly fleeing from the echolocation clicks of a foraging sperm whale. 

Upon its death, that same echolocating sperm whale was found with its teeth worn down to stumps, similar to those of orcas (Orcinus orca) that feed on Pacific sleeper sharks (Somniosus pacificus). Greenland sharks are closely related to Pacific sleeper sharks and have similarly tough skin. To explain the sperm whale tooth wear and a fleeing Greenland shark, Harvey-Clark theorized that the sperm whale hunted Greenland sharks. Scientists have yet to observe sperm whales hunting these sharks elsewhere.

Related: Sperm whales outwitted 19th-century whalers by sharing evasive tactics

Are Greenland sharks dangerous?

There are no verified reports of Greenland shark attacks on humans. However, some anecdotal evidence suggests that such attacks could occur. GEERG divers observed a Greenland shark "stalk" a team of divers. They have also seen Greenland sharks investigate diver activities as if they were scouting seal prey, according to the ORS. A Greenland shark was reportedly found with a human leg in its stomach off Canada's Baffin Island around 1859, but this report was not verified. 

Is Greenland shark meat toxic?

Untreated Greenland shark meat is toxic to humans. Their meat contains high levels of trimethylamine oxide (TMAO), which breaks down into the poisonous trimethylamine (TMA) compound during digestion, according to a 1991 study published in the journal Toxicon. TMA can cause severe intestinal problems and produces similar effects to excessive alcohol consumption. 

Greenland shark meat is edible only when dried. The dried meat is fed to sled dogs in northern regions such as Greenland, according to the Florida Museum of Natural History. The meat is also fermented and consumed by people inIceland, where the food, called Hákarl, is considered a delicacy. 

Are Greenland sharks endangered?

The IUCN considers Greenland sharks to be vulnerable to extinction. Humans killed Greenland sharks for their liver oil to use in lamps and other products between the 13th and 20th centuries. The commercial fishing of Greenland sharks for their oil ended by the 1960s, which helped their population rebound. However, Greenland sharks continue to be caught and killed as bycatch, or animals that get pulled up by fishers alongside their intended catch, for example, in large nets dragged along the bottom of the ocean intended to catch a large number of fish. Most of the Greenland sharks eaten by humans and fed to dogs come from bycatch, although some sharks are targeted on a small scale. 

The Northwest Atlantic Fisheries Organization (NAFO), an intergovernmental fishing science and management body, prohibits the direct fishing of Greenland sharks and seeks to reduce bycatch. The NAFO applies to most fisheries in the northwest Atlantic Ocean and includes countries such as the U.S. and Canada. But thee IUCN recommends the development and enforcement of further protections, such as bycatch policy, for Greenland sharks. 

The IUCN estimates that the Greenland shark population has declined by 30% to 49% over the past 450 years, or three shark generations. However, this decline was estimated based on a conservative Greenland shark life span of 150 years; the decline could be much higher if the sharks have longer life spans and thus take longer to reach reproductive age and produce more sharks. The global Greenland shark population size is unknown. Climate change is also hurting the species — for example, by reducing Arctic sea ice, which gives fishing fleets easier access to Greenland shark habitat.  

Additional resources

Visit the Encyclopedia of Life website for more information about where these sharks live. The website provides an interactive map of Greenland shark observations around the world. You can see more photos and videos of Greenland sharks and other deep sea creatures on the NOAA Ocean Exploration website. Preparing Greenland shark meat for human consumption is a long process that we don't delve into on this page. To find out more about the process, you can watch this short video on YouTube from Food Insider.

There aren't reliable books on Greenland sharks specifically, but for a general guide to the world's sharks, check out "Sharks of the World: A Complete Guide" (Princeton University Press, 2021).  

Bibliography

• Alister Doyle, Reuters, "Polar bear eaten by shark: who's top predator?" Aug. 11, 2008. https://www.reuters.com/article/us-arctic/polar-bear-eaten-by-shark-whos-top-predator-idUSLB66891920080811 
• Anthoni et al. "Poisonings from flesh of the Greenland shark Somniosus microcephalus may be due to trimethylamine," Toxicon, Volume 29, 1991. https://pubmed.ncbi.nlm.nih.gov/1801314/ 
• Chris Harvey-Clark, Capeia, "Unknown Monster, Dreamless Sleeper: the Greenland Shark II," Aug. 12, 2017. https://beta.capeia.com/zoology/2017/06/14/unknown-monster-dreamless-sleeper-the-greenland-shark-ii 
• Encyclopedia of Life, "Ommatokoita elongata." https://eol.org/pages/1037051
• Florida Museum of Natural History, "Carcharodon carcharias," Oct. 18, 2018. https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/carcharodon-carcharias/ 
• Florida Museum of Natural History, "Somniosus microcephalus," Dec. 5, 2019. https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/somniosus-microcephalus/ 
• Kulka et al. "Somniosus microcephalus, The IUCN Red List of Threatened Species," 2020. https://www.iucnredlist.org/species/60213/124452872 
• Mills, P, Animal Diversity Web, "Somniosus microcephalus," 2006. https://animaldiversity.org/accounts/Somniosus_microcephalus/
• Mindy Weisberger, Live Science, "Greenland Sharks May Live 400 Years," Dec. 15, 2017. https://www.livescience.com/55736-greenland-sharks-longest-lived-vertebrates.html 
• National Oceanic and Atmospheric Administration (NOAA), "How long do Greenland sharks live?" March 1, 2021. https://oceanservice.noaa.gov/facts/greenland-shark.html 
• Nielsen et al. "Assessing the reproductive biology of the Greenland shark (Somniosus microcephalus)," PLOS One, Volume 15, Oct. 7, 2020. https://doi.org/10.1371/journal.pone.0238986 
• Nielsen et al. "Distribution and feeding ecology of the Greenland shark (Somniosus microcephalus) in Greenland waters," Polar Biology, Volume 37, Oct. 10, 2013. https://link.springer.com/article/10.1007/s00300-013-1408-3 
• Nielsen et al. "Eye lens radiocarbon reveals centuries of longevity in the Greenland shark (Somniosus microcephalus)," Science, Volume 353, Aug. 12, 2016. https://www.science.org/doi/abs/10.1126/science.aaf1703 
• St. Lawrence Shark Observatory (ORS), "Meet the world's oldest-living vertebrate, the Greenland Shark," 2019. https://geerg.ca/en/greenland-shark/ 

Lions, gray wolves and great white sharks have one thing in common: They're top predators. Their diets consist almost entirely of meat, and except in rare instances, these animals have no natural predators — except humans. So, if we are predators of top predators, does that mean humans are at the top of the food chain?

The answer depends on how you define "predator," that is, whether you're killing to eat or just killing other animals, as well as whether you're looking at prehistoric or modern-day humans.

In ecology, or the study of how organisms relate to one another and to their environments, humans' place in the food chain isn't based on what does or doesn't eat us, or on what we kill, said Sylvain Bonhommeau, a marine ecologist at IFREMER, a marine research institute in France. Rather, "It's completely based on what you eat," Bonhommeau told Live Science. Based on that definition, the answer is no — humans aren't top-predators because we don't eat everything we kill.

Related: What's the first species humans drove to extinction?

Bonhommeau and colleagues at IFREMER set out to determine humans' position on the food chain, also known as their trophic level. Scientists typically score trophic levels on a scale of 1 to 5. Plants and other primary producers, which obtain energy using sunlight, occupy level one, and herbivores are in level two. Meanwhile, species at the third level eat only herbivores, and species at the fourth level eat only level-three carnivores — and so on. Species that get their food from multiple trophic levels, like omnivores, are scored by the average trophic level of what they eat, plus one. For example, an animal that eats exactly 50% plants and 50% herbivores would be a level 2.5-omnivore.

Using data from the Food and Agriculture Organization of the United Nations on human food consumption around the world, the IFREMER scientists assigned a trophic level to each food we eat. They found that, on average, humans get 80% of their daily calories from plants and 20% from meat and fish, according to the team's 2013 study results, published in the journal Proceedings of the National Academy of Sciences. That puts us at an average trophic level of 2.21 — somewhere between anchovies and pigs. But humans' trophic levels vary worldwide. In Burundi, for instance, plants made up 96.7% of the local diet in 2009, giving those in that country a trophic level of 2.04. Meanwhile, those in Iceland, where the diet consisted of around 50% meat that same year, had a trophic level of 2.57.

Of course, humans pose a much larger threat to other animals than anchovies and pigs do. Some scientists argue that humans' pressure on other species makes us "super predators," a term the authors coined to refer to the rate at which humans kill other species. In a 2015 report published in the journal Science, scientists at the University of Victoria in Canada compared the activity of human hunters and fishers with that of other terrestrial and marine predators. They found that humans kill adult prey at rates up to 14 times higher than other predators. "If you take into account how wide our impact on wildlife is, it's huge," Bonhommeau said. However, Bonhommeau disagrees with the assessment that humans are super-predators, which he interprets as a conflation with the term "top-predator." (The authors of the Science paper were not available for comment.) In ecology, predator has a specific definition: they eat what they kill. "I think this article was misleading by confusing killing and predating (kill and ingest food)," he wrote in an email.

For the most part, we're not killing wildlife to eat them. For instance, the main causes of lion population declines are habitat loss and clashes with humans, who don't want lions threatening them or their livestock. Meanwhile, people fishing the oceans throw away between 10% and 20% of total catches as bycatch, according to a 2017 study in the journal Fish and Fisheries. These unintentionally caught animals often sustain injuries or die, according to the National Oceanic and Atmospheric Administration. "A predator ingests what it kills," Bonhommeau and colleagues wrote in an unpublished response to the Science article. Instead, they suggest the term "super-consumer."

Related: Humans are practically defenseless. Why don't wild animals attack us more?

Historically, there may have been less of a discrepancy between what we eat and how much we kill. Ben-Dor and colleagues reviewed studies on human physiology, genetics, archaeology and paleontology to reconstruct the trophic levels of our Pleistocene (2.6 million to 11,700 years ago) ancestors. 

They concluded that humans likely were apex predators who ate mostly meat for around 2 million years, up until 12,000 years ago, when the last ice age ended. The review, published in 2021 in the American Journal of Biological Anthropology, argued that humans have more physiological similarities to carnivores than to herbivores, such as highly acidic stomachs to break down complex proteins and kill harmful bacteria, and the high body fat capable of carrying carnivores through a period of fasting before the next big kill. 

The scientists also pointed out that an analysis of different nitrogen isotopes (variants of the element nitrogen) in ancient human remains, the ratio of which tends to increase with a meat-heavy diet, reveals consistently high ratios of nitrogen compared with the ratios of nitrogen isotopes in the fingernails and hair of people with a primarily plant-based diet. This analysis, in essence, is another line of evidence that ancient humans ate a ton of meat.

A few changes may have caused humans to descend the food chain, Ben-Dor and colleagues write in their review article. The primary change, they suggest, was the disappearance of large animals like woolly mammoths. Around that same time, humans began to develop technology that allowed them to consume a higher number of plants, like stone tools for processing grains. (The advent of agriculture was still just around the corner.) 

But even if we were once apex predators with meat-heavy diets, that doesn't mean modern humans should ascend the trophic ladder, Ben-Dor told Live Science. "It doesn't necessarily follow that because we were carnivores in the past, we are today at the top of the food chain," he said. "However, our love for meat has everything to do with our Pleistocene carnivorous past."

Originally published on Live Science.

When giant cousins of infamous "murder hornets" attack the hives of Asian honey bees, the bees produce a loud and frantic buzzing that resembles the panicked calls made by some types of birds and mammals if a predator is near.

Giant hornets (Vespa soror) are a sister species to so-called murder hornets (Vespa mandarinia). They're also one of the deadliest predators of Asian honey bees (Apis cerana). They attack hives in groups until they overwhelm the colony and kill or drive off the adults, then serve the bee brood as tender meals for their own hornet youngsters.

If these giant and aggressive hornets come calling, bees don't keep quiet about it, and their buzzy "shrieks" in response to the appearance of a giant hornet are louder and more intense than alarm calls about other hornets. The bees even produce a special type of "scream" in response to giant hornets; this bee-spoke response may help to alert the colony about an especially dangerous threat.

Related: Photos: Murder hornets will haunt your nightmares

Researchers first heard the screaming of the bees in Vietnam while investigating another of the bees' defensive maneuvers against giant hornets: smearing animal poop around the openings of their hives, said study lead author Heather Mattila, an associate professor in the Department of Biological Sciences at Wellesley College in Massachusetts. 

"They collect dung from farm animals and apply that in spots around the entrances to repel hornets," Mattila told Live Science. "When we were there in the bee yard, I remember saying to my colleagues, 'These colonies are making a lot of noise.' So we started listening," she said. "It seemed like every time the giant hornets showed up — or right after they'd left — you could stand beside the colony and hear the bees inside freaking out."

To confirm what was going on, the researchers recorded video of hive exteriors and audio of the bees inside the hives, in colonies at three apiaries from late August through October 2013. They captured recordings of the hives during normal activity, and when the hives were assailed by giant hornets and by smaller hornet predators, Vespa velutina. The scientists then used audio-visualizing software to examine these colony soundscapes, identifying nearly 30,000 worker-produced signals.

Their next step was to catalog different sounds that the bees were making. Finally, the researchers matched sounds to bee and hornet activity outside the hive to see if they could link certain buzzing patterns to specific triggers. Organizing "a mess of signals" from hives teeming with stressed-out bees was extremely challenging, "so it took us years to tease out what was going on," Mattila said. 

A bustling space

Prior research has shown that bees communicate vibroacoustically, through a combination of airborne sounds that they sense through their antennae and vibrations that they detect with their legs. One of these signals is called a hiss, in which bees move their bodies and simultaneously vibrate their wings; another is known as a pipe, when a worker thrums her thorax and then butts her head against a hivemate or presses her body to a surface, thereby transmitting the signal.

It turned out that Asian honey bees hissed and piped to each other almost constantly, even when their hives were undisturbed. But when a giant hornet showed up, the hissing and piping ramped up and became cacophonous, the study authors wrote. Bees also produced specific pipes when giant hornets were near, which the scientists called "antipredator pipes." These signals were repeated in short bursts, but not in a regular pattern; there were also rapid frequency changes and an overall "harsh noisiness" to the sounds, Mattila said. 

All of those acoustic features — irregular patterns and dramatic changes in frequency and amplitude — are also found in the attention-grabbing panic calls of animals such as meerkats and primates when they spy a deadly predator, the scientists reported. Bees even produced antipredator pipes in response to paper saturated with the chemical scent that attacking giant hornets use to mark beehives, though their response intensified when real hornets showed up, Mattila told Live Science. However, further study will be required to understand the role of antipredator pipes alongside honey bees' other defensive behaviors against giant hornets, she added.  

Many types of hornets in the Vespa genus prey on Asian honey bees, so beekeepers in Vietnam protect their hives by standing guard with electrified tennis rackets, Mattila said. But of all the hornet predators, giant hornets are the biggest threat; just one attack can wipe out an entire colony, which could explain why bees have evolved to have a special signal for a giant hornet attack.

"Asian honey bees have been in a long war with these giant hornets," Mattila said. "It doesn't surprise me that they have pretty specific ways of communicating to try and be clear with each other about what they're facing."

The findings were published Nov. 10 in the journal Royal Society Open Science.

Originally published on Live Science.

A winding lava-tube cavern in northern Saudi Arabia was home to hyenas for millennia, and they left behind plenty of gruesome evidence of past meals. The floor of the cave system was covered in deep piles of gnawed bones — some of which belonged to people. 

Hyenas often scavenge their meals, so they probably didn't kill their human prey, but rather, dug up cadavers from nearby burials and devoured them in this underground den, scientists recently reported.

Other researchers described the western part of the lava tube site in 2009 as the "Wolf Den," because they suspected that wolves were responsible for the vast collection of bones. However, new analysis of the bone piles, coprolites (preserved feces) and individual bones told a different story. Scientists now suspect that the den belonged to striped hyenas (Hyaena hyaena), which fed on a variety of animals — including humans — in that location from at least 4,500 years ago until as recently as 150 years ago. 

Related: 5 reasons hyenas like Harley Quinn's 'Bruce' are amazing

Lava tubes are underground passageways carved by rivers of lava that can reach temperatures exceeding 2,000 degrees Fahrenheit (1,090 degrees Celsius), according to the National Park Service Hawai'i. When lava flows are trapped in pools by rock walls, they can heat up and begin eating through the crust below, creating subterranean channels and networks. Once the flows subside or get diverted, tunnels that are left behind can extend as long as 40 miles (65 kilometers) and measure several dozen feet wide, NPS Hawai'i says. 

For the new study, the researchers investigated part of Saudi Arabia's Umm Jirsan lava tube — the longest such network in the country. Located in the Harrat Khaybar lava field, this tube is made up of three passages separated by two collapsed walls of rock, scientists reported July 20 in the journal Archaeological and Anthropological Sciences. Umm Jirsan measures about 4,900 feet (1,500 m) long, with a passage height of about 26 to 29 feet (8 to 12 m).

The scientists focused on the lava tube's western passage, which contained "an extremely dense accumulation of bones," the authors wrote. They examined more than 1,900 bones, identifying 40 individual creatures. Most of the bones belonged to donkeys, followed by caprines — a type of goat — gazelles, camels and wolves or dogs. The scientists identified two human skull fragments at this location, "and a number of others [human bones] were discovered in other parts of the Umm Jirsan system," they wrote in the study. 

Other sites from elsewhere in the Middle East and Africa contain similar bone hoards that are thought to span thousands of years, but the data from those locations isn't as complete as the evidence from Umm Jirsan, raising questions about how long those dens were actually in use, said lead study author Mathew Stewart, a postdoctoral researcher in the Department of Archaeology at the Max Planck Institute for the Science of Human History in Jena, Germany.

Patterns of wear on the bones from chewing, licking and partial digestion matched marks left on bones by modern hyenas, and the enormous quantities of discarded bones also hinted at hyenas' habits, according to the study. Striped hyenas are also known for denning deep in cave networks. And while wolves tend to do most of their eating at the site of a kill, hyenas avidly hoard meaty bones in their dens; their powerful neck and jaw muscles enable them to carry heavy carcasses for great distances and crack large bones to reach the marrow inside, the authors reported.

"Striped hyena[s] were the most likely accumulator of bones at Umm Jirsan," Stewart told Live Science in an email. 

But even if those hyenas were dining on human flesh, that doesn't necessarily mean that they were hunting people, Stewart added.

"While predation of humans is possible — and some instances of predation on modern humans [have] been noted — the human remains at Umm Jirsan are likely due to striped hyena scavenging from human grave sites," Stewart said.

In addition to providing a glimpse of hyena habits spanning thousands of years, Umm Jirsan also preserves a broader snapshot of biodiversity in a region "where bone and fossil preservation is otherwise exceptionally poor," Stewart said. "Sites like these may hold potential keys to understanding the environments and ecologies of the past in arid regions like Arabia."

Originally published on Live Science.

Twenty-five million years ago, an eagle with half-foot long talons snatched ancient koalas out of trees in Australia, a new study suggests.

Paleontologists discovered 63 fossilized bones from the ancient koala-hunter in 2016, while on an expedition to Lake Pinpa, a salt lake east of the Flinders Ranges in South Australia. After thoroughly examining the bones, the team recently named the newfound eagle species Archaehierax sylvestris. The ancient raptor has no direct descendants living today, they determined.

Since the bones date to the Oligocene epoch, which lasted from 33.9 million to 23 million years ago, the A. sylvestris specimen represents the oldest eagle fossil ever found in Australia, as well as one of the best preserved, the scientists reported Sept. 27 in the journal Historical Biology.

Related: Ancient footprints to tiny 'vampires': 8 rare and unusual fossils 

"As apex predators, eagles and hawks are less abundant than the species they prey on," first author Ellen Mather, a doctoral student at Flinders University in Adelaide, Australia, told Live Science in an email. "This tends to carry over into the fossil record, as there are fewer chances an individual from these species will be fossilized." 

And when they are found, eagle fossils often include very few bones — or sometimes only one — making the newfound fossil, with its 63 bones, an exceptionally rare find, the authors noted in their report.

Nowadays, Lake Pinpa, where the fossil was found, rarely holds any water and sits within a landscape of sand dunes sparsely adorned with grass and trees. But back when A. sylvestris soared through the skies, the lake looked strikingly different, senior author Trevor Worthy, a vertebrate paleontologist and associate professor at Flinders University, told Live Science in an email. 

At that time, the Lake Pinpa excavation site sat on the shore of a larger lake, or lake system, which extended for about 62 miles (100 kilometers) through a temperate rainforest. Fossil records indicate that fish, crocodiles and freshwater dolphins populated the lakes, and an array of shorebirds, possums and ancestral koalas hung out on the shore.

"Lake Pinpa, as a whole, is the most rich fossil site for this time period in South Australia," Worthy said. The earliest known ancestors of modern marsupials, such as bandicoots, possums, kangaroos and wombats, have all been found at the site, along with many avian herbivores, such as ducks and cormorants. But even in this treasure trove of ancient Australian fossils, hawk and eagle specimens have been few and far between, he said.

When Worthy's team first discovered the A. sylvestris fossil in 2016, "we knew instantly we had a large bird, but it was highly fragmented and so not spectacular," he said. Among the first bone fragments they excavated, the team found claws and a lower leg bone called a tarsometatarsus; these bones revealed that the specimen was an eagle, but at that time, they didn't know which species. So they carefully scooped up the bones in a big lump of sediment, encased the whole lot in plaster and shipped the specimen back to their lab. 

Related: Photos: Birds evolved from dinosaurs, museum exhibit shows 

Worthy and the team then carefully freed the bone bits from their surrounding sediment, one piece at a time, and jig-sawed all the bits back together into complete bones. Some bones contained as many as 20 tiny fragments, Worthy said. Mather then compared the assembled bones with those of various falcons, ospreys, eagles and hawks. Based on this analysis, she determined that the fossil belonged to a family of raptors called Accipitridae, which includes hawks, eagles, kites and Old World vultures. 

That said, specific features of the newfound fossil, such as the spacing of its toes and insertion points for its leg muscles, set the bird apart from other members of the Accipitridae family, Mather said. Based on these features, as well as the age of the Lake Pinpa site, the team concluded that the bird belonged to a previously unknown subfamily and species of eagle.

"We can be confident that the fossil represents a new species as the only other eagle species of a similar age, Pengana robertbolesi from Riversleigh, Queensland, has a very different morphology from Archaehierax," Mather said. 

The unique features of the A. sylvestris bones also hinted at the ancient bird's hunting style. The eagle had a 5.9-inch-long (15 centimeters) foot-span and long legs compared with its overall size, meaning the predator was equipped with the perfect tools to reach out and snatch large prey from the treetops. And the eagle's relatively short wings hint that, while not a particularly fast flier, A. sylvestris likely excelled at dive-bombing unsuspecting koalas from above.

Although eagle fossils are generally hard to come by, at certain excavation sites, they're relatively common, Mather noted. For example, at the La Brea Tar Pits in Los Angeles, eagles and other predators would become trapped in tar while attempting to eat other animals in the pits; that means today, a fair number of predator fossils can be found at the site.

"However, this is not the case at Lake Pinpa," where no specific feature of the environment favors the preservation of predators, Mather said. "The fossilization of our eagle was a matter of luck."

Originally published on Live Science.

With ecosystems as varied as oceans, plains and frozen tundras, North America is home to some giant and ferocious predators. But these modern creatures — including alligators, great white sharks and polar bears — look minuscule next to the continent's slew of ancient predators. So, what are the largest predators that have ever lived in North America?

As for furry animals, North America's largest predatory mammal was probably the massive short-faced bear (Arctodus simus), said Ross MacPhee, senior curator of mammals at the American Museum of Natural History in New York City. Sometimes affectionately called the "bulldog bear," this now-extinct creature had a signature short, broad muzzle. It stood around 5.5 feet (1.6 meters) tall at the shoulder and over 11 feet (3.4 m) on its lanky hind legs, according to the University of Iowa Museum of Natural History. 

It can be difficult for scientists to gauge the exact body weight of an extinct species, because they have to extrapolate those numbers using existing species as benchmarks, MacPhee told Live Science in an email. However, paleontologists comfortably estimate that the short-faced bear probably weighed around 1,540 pounds (700 kilograms). Modern polar bears (Ursus maritimus) aren't too far off — the largest males stand around 5 feet (1.5 m) at the shoulder and weigh around 1,300 pounds (600 kg), according to Polar Bears International. 

Related: Why do animals hibernate?

Short-faced bears went extinct about 11,000 years ago, around the end of the last ice age. To find a more massive land predator, we'll have to travel further back in time. The largest predatory North American dinosaur is also the continent's most famous: the king, Tyrannosaurus rex. 

During the late Cretaceous period, about 100 million to 66 million years ago, North America was a land of monsters. "Carnivorous dinosaurs had incredible variety in North America across the Mesozoic [252 million to 66 million years ago]," Andrew Farke, director of the Raymond M. Alf Museum of Paleontology in Claremont, California, told Live Science in an email. There was the spiny-backed Acrocanthosaurus, the sharp-clawed Deinonychus, and the slender, feathery Microvenator. 

But at nearly 12 feet (3.5 m) tall at the hips and up to 40 feet (12.3 m) long, according to a nearly-complete, school bus-size T. rex specimen known as Stan, the terrible tyrant rex towered over most of its carnivorous contemporaries. Acrocanthosaurus, a "shark-toothed" cousin of tyrannosaurs and member of a group known as carcharodontosaurs, nearly matched T. rex's length but was lighter, weighing 6.8 tons (6.1 metric tons), compared with T. rex's 7.8 tons (7.1 metric tons), according to the American Museum of Natural History. T. rex used all that bulk to its advantage: With its powerful jaw muscles, it could deliver up to 6 tons (5.4 metric tons) of pressure per bite — enough to tear through steel as if it were a piece of paper, according to a 2019 study in the journal The Anatomical Record.

The only dinosaurs alive today are birds, making the largest living dinosaur in North America the California condor (Gymnogyps californianus). At 10 feet (3 m) from wing tip to wing tip, this bird is significantly smaller than its ancient meat-eating cousin T. rex, but formidable in its own right, feeding on the carcasses of deer, pigs, cattle, sea lions and even whales, according to the Cornell Lab of Ornithology.

When it comes to ancient sea behemoths, a giant reptile takes the cake. Ichthyosaurs were a group of predatory marine reptiles that lived during the Mesozoic era, the same time period as the dinosaurs. In the late Triassic period, roughly 237 million years ago, an ichthyosaur known as Shonisaurus sikanniensis began swimming in the waters of what is now British Columbia, Canada.

"S. sikanniensis is regarded as the largest known marine reptile of all time," Kenshu Shimada, a professor of paleobiology at DePaul University in Chicago, told Live Science. There is some debate about which ichthyosaur genus S. sikanniensis belonged to: Shastasaurus or Shonisaurus. Members of both genera were large, streamlined and speedy, though species of the Shonisaurus genus had barrel-shaped chests and long snouts compared with the slender, shorter-snouted Shastasaurus, according to University of Portsmouth paleontologist and paleoartist Mark Witton.

 Regardless of taxonomy, there is no question that S. sikanniensis was absolutely colossal; it measured an astonishing 65 feet (20 m) long from snout to tail, "easily about three times longer than the largest known living great white shark," Shimada said. But size doesn't always equal ferocity. A 2011 study in the journal PLOS One suggested that S. sikanniensis may have been a suction feeder, slurping up soft-bodied prey such as squids and belemnites (shelled squids).

Each of these creatures, however, eventually died out as the result of environmental upheaval. Like many highly specialized predators, once their prey became scarce, they simply couldn't keep up with their energy needs. "At a certain point, bigger is not better," MacPhee said.

Originally published on Live Science.

"They are more afraid of you than you are of them" is a saying that is often used to reassure hikers that even large predators, such as bears and pumas, pose little threat to us. But humans are slower and weaker than these animals, so what stops these beasts from snacking on every clothed ape they come across? 

There are a few likely reasons why they don't attack more often. Looking at our physiology, humans evolved to be bipedal — going from moving with all four limbs to walking upright on longer legs, according to John Hawks, a paleoanthropologist at the University of Wisconsin-Madison.

"There is a threat level that comes from being bipedal," Hawks told Live Science. "And when we look at other primates — chimpanzees, gorillas, for instance — they stand to express threats. Becoming larger in appearance is threatening, and that is a really easy way of communicating to predators that you are trouble." 

Related: How many early human species existed on Earth?

Bipedalism may make humans appear bigger and therefore more threatening to other species, but it also has disadvantages. It is typically slower to move on two legs than on four, meaning humans have abandoned any pretext of outrunning any four-legged creature, according to Hawks. 

"It's sort of like a bluff," Hawks said. "It's like, 'I'm walking around; I'm tough; I'm showing where I am on a landscape.'" Predators see the upright stance and assume humans are tougher than we actually are, according to Hawks. However, even if they were to call our bipedal bluff, predators have other reasons to leave us alone. 

Larger primates, such as humans and chimps, live in groups and adopted the strategy of aggressively defending themselves against threats, which usually works against predators, Hawks said. Being social has therefore helped keep us safe, along with the benefits of bipedalism.

As human technology advanced, we developed an arsenal of advanced weapons, such as bows and guns, that could be used from a distance. With these weapons, humans became so deadly that they began taking the fight to predators. 

Another reason humans are rarely attacked by large wild animals is that their numbers have declined. "We've been trying to essentially clear the landscape that we use of large predators for a very long time," Justin Suraci, lead scientist in community ecology and conservation biology at Conservation Science Partners, a nonprofit conservation science organization based in California, told Live Science. 

Large predators and their habitats suffered great losses in the United States before and into the 20th century, before the passing of the Endangered Species Act of 1973, Suraci noted. For example, humans hunted, trapped and poisoned wolves (Canis lupus) to near extinction, Live Science previously reported, and pumas (Puma concolor) were wiped out of the entire eastern half of North America, except for a small population in Florida, according to the International Union for Conservation of Nature. 

Related: What's the first species humans drove to extinction? 

Predators living in other areas that are heavily populated by humans have faced similar problems. According to Suraci, the animals that have escaped human menace likely learned to become wary of our species. "For very logical reasons, some of these larger predators have a healthy fear of humans in the same way that any prey species would fear its predators," Suraci said. 

In a 2019 study published in the journal Ecology Letters, Suraci and his colleagues played recordings of human voices through remote speakers in the Santa Cruz Mountains of California. The study showed that the sound of humans talking was enough to scare away pumas and several smaller predators, such as bobcats (Lynx rufus).

The recordings were designed to simulate benign conversation and consisted mostly of Suraci and his friends reciting poetry and passages from books. The effect was so strong, the recordings had a similar effect to removing predators from an ecosystem altogether, with reduced predator activity allowing small, would-be prey animals, like mice, to forage more than they normally would. 

Suraci thinks this fear that predators have of humans could also have an upside: It could help prevent conflict between humans and wildlife. Large predators need a lot of space, and in a human-dominated world, they need to be able to live alongside humans without conflict.

"The fear of humans that a lot of these predators show is really positive in that light," Suraci said. "It gives us some opportunity to potentially share spaces with these animals — to go hiking in places where pumas, bears and wolves all exist, without experiencing any negative impacts." 

Put another way, wild predators' "healthy fear" of humans may help us coexist, "as long as we're conscious about their presence," Suraci said. Indeed, it's important to be smart while hiking in regions where large predators live. For instance, in bear country, people should hike in groups and periodically yell "Hey bear," to give animals time to leave the vicinity before an encounter, Live Science previously reported. 

Originally published on Live Science.

A hippopotamus-size predator that lived 265 million years ago was unexpectedly speedy for such a bulky beast. 

Scientists previously viewed the dinosaur-like reptile Anteosaurus as slow and plodding because of its massive, heavy head and bones. However, a new analysis of the animal's skull proved otherwise, revealing adaptations that would have made Anteosaurus a fast-moving juggernaut.   

With this deadly combination of speed and power — along with a mouthful of bone-crushing teeth — Anteosaurus would have been one of the most fearsome apex predators on the African continent during the middle part of the Permian period (299 million to 251 million years ago), according to a new study. 

Related: Wipe out: History's most mysterious extinctions

Anteosaurus belonged to a reptile family that predated dinosaurs, known as dinocephalians, and they all died out about 30 million years before the first dinosaurs appeared. Dinocephalians were also part of a larger group of animals called therapsids, which includes the ancestors of mammals.

"Dinocephalians were among the first herbivorous and carnivorous species that dominated terrestrial ecosystems," said lead study author Julien Benoit, a senior researcher at the Evolutionary Studies Institute at the University of the Witwatersrand (Wits University) in Johannesburg, South Africa. 

What's more, dinocephalians were some of the earliest amniotes — animals that hatch from eggs laid on land or retained inside the mother's body — to evolve very large body size, according to the study. Many dinocephalians also had sturdy skulls with reinforced horns, buffers and bumps, suggesting that the animals may have used their heavy heads as battering rams. 

Heavy ... and amphibious?

Because Anteosaurus' skeleton was so massive, researchers previously hypothesized that it was a slow-moving animal that likely ambushed its prey, Benoit told Live Science in an email. 

"Some authors even suggested that it might have been amphibious because it was just too heavy to support its weight on land — similar to what used to be imagined about dinosaurs," Benoit said. "Our study suggests it is quite the opposite."

Anteosaurus had a weighty, knobby skull with a prominent crest on the snout, and Benoit and his co-authors questioned if Anteosaurus was a head-butter, like some of its dinocephalian relatives. To find out, they scanned the skull of a juvenile Anteosaurus magnificus from the Karoo desert region in South Africa. 

They used X-ray microtomography (micro-CT) to create high-resolution images that revealed the interior of the skull in exceptional detail and then used those images to reconstruct the skull and its long-gone internal structures as digital 3D models.

Their scans provided the first-ever glimpse of an Anteosaurus' inner ear — and it was definitely not the inner ear of a head-butting animal, Benoit said.

"When the skull is adapted to head butting, the inner ear is tilted backward because of a reorientation of the braincase to absorb head-to-head combat stress," Benoit said. But A. magnificus lacked that adaptation, so it probably didn't use its head for ramming. 

"Instead, it would have used its massive canines for fighting," Benoit said.

An agile killer

The scientists also found surprising clues about Anteosaurus' abilities by reconstructing and measuring the dimensions of its inner ear canal, which is a feature associated with balance, and lobes in its cerebellum called the flocculi, which assist with agility and help predators lock their eyes on their prey. The shapes of these structures resembled those found in predators such as cats and velociraptors, hinting that Anteosaurus had a nervous system adapted to catching fast-moving prey, Benoit said. 

"When you contemplate the bones of this animal, they look so heavy and massive that this really came up as a surprise," he said. "I guess this comes in part from the misconception that fossilized bones are so heavy, it is hard to imagine that they were once light and pulled by muscles powerful enough to make them move."

Superior swiftness and agility would have enabled Anteosaurus to prey on another group of big-skulled and formidable Permian reptiles known as therocephalians, or "beast-heads," placing it at the top of the food chain, according to the study. And this is just the beginning of what researchers are yet to discover about the strange reptiles that came before the dinosaurs, Benoit said.

"Soon we will be capable of comparing the brain and inner ear of Anteosaurus to many of its close relatives," he said. "This will shed new light on the interactions between animals of an entirely extinct ecosystem." 

The findings were published online Feb. 18 in the journal Acta Palaeontologica Polonica.

Originally published on Live Science.

For knife-toothed kukri snakes, the tastiest parts of a frog are its organs, preferably sliced out of the body cavity and eaten while the frog is still alive. After observing this grisly habit for the first time in Thailand, scientists have spotted two more kukri snake species that feast on the organs of living frogs and toads.

The new (and gory) observations suggested that this behavior is more widespread in this snake group than expected. Two snakes also eventually swallowed their prey whole, raising new questions about why they would extract the living animals' organs first.

The scientists documented a Taiwanese kukri snake (Oligodon formosanus) and an ocellated kukri snake (Oligodon ocellatus) pursuing amphibian organ meals, tearing open frogs' and toads' abdomens and burying their heads inside, according to the studies. O. formosanus would even perform "death rolls" while clutching its prey, perhaps to shake the organs loose. As the snakes swallowed the organs one by one, the amphibians were still alive. Sometimes, the process would take hours, the researchers reported.

Related: Beastly feasts: Amazing photos of animals and their prey

There are 83 species of kukri snakes in the Oligodon genus in Asia. The snakes typically measure no more than 3 feet (100 centimeters) long, and the group's name comes from the kukri, a curved machete from Nepal, as its shape is reminiscent of the snakes' large, highly modified rear teeth. Kukri snakes use these teeth for slicing into eggs, but they can also be formidable slashing weapons (as some very unfortunate frogs have discovered).

In one study, published Feb. 15 in the journal Herpetozoa, scientists described three snake attacks on rotund banded bullfrogs (Kaloula pulchra), which are so round that they are also known as bubble frogs or chubby frogs. They have brown backs with lighter stripes down their sides and cream-colored stomachs, and they measure up to 3 inches (8 cm) long, according to Thai National Parks. 

Two of the attacks were by Taiwanese kukri snakes, and took place in Hong Kong in October 2020. One snake, filmed on Oct. 2 in a residential neighborhood garden, emerged from a hole in the ground to bite a passing bubble frog, slicing open the frog and stuffing its head inside. Snake and frog tussled for about 40 minutes; the snake performed about 15 body rotations, or "death rolls," during the battle, according to the study. 

"We believe that the purpose of these death rolls was to tear out organs to be subsequently swallowed," Henrik Bringsøe, lead author of both studies and an amateur herpetologist and naturalist, said in a statement.

A second Taiwanese kukri snake was discovered on Oct. 8 in an urban park while "energetically" dining on a frog's organs that were "exposed and visible," the study authors wrote.

The third attack on a bubble frog was by a small-banded kukri snake — the species that was first documented exhibiting this behavior — on Sept. 15, at a factory site outside a small village in northeastern Thailand. During the struggle, the snake performed 11 death rolls, its teeth buried firmly in the frog's belly.

"The snake’s efforts resulted in its teeth penetrating the abdomen to such an extent that blood and possibly some organ tissue appeared," the scientists reported. "Eventually, the frog was swallowed whole while still alive."

Another study, published on the same day in Herpetozoa, presented an observation of an ocellated kukri snake feasting on an Asian common toad (Duttaphrynus melanostictus) inside a lodge in a national park in southern Vietnam. These toads are stout, thick-skinned and variably colored, and they measure about 3 inches (8.5 cm) long, according to Animal Diversity Web, a biodiversity database maintained by the University of Michigan's Museum of Zoology. 

Observers recorded this attack on May 31, 2020. The toad was already dead at the time, "and the snake was moving its head and neck side to side as if trying to work its way inside," the study authors wrote. Minutes later, the snake gulped down the toad whole.

In the 2020 study about small-banded kukri snakes eviscerating Asian common toads, the scientists hypothesized that the snakes selectively ate the organs to avoid the toads' deadly toxins. However, the ocellated kukri snake swallowed the toad after its organ appetizer, hinting that the snakes might have some natural resistance to the toads' poison. 

Chubby frogs also have a built-in deterrent that may encourage predators to go straight for their organs. While the frogs aren't toxic, they defensively secrete a sticky mucous that has an unpleasant taste, according to the University of California, Berkeley's AmphibiaWeb.

"We hope that future observations may uncover additional aspects of the fascinating feeding habits of kukri snakes — though we may indeed call them gruesome!" Bringsøe said in the statement.

Originally published on Live Science.

When a sparrow's nest flooded during high tide in coastal Georgia, a fish jumped at the chance to make a meal of a newly hatched chick, and a scientist's video camera caught a first-ever view of the entire deadly encounter.

Footage showed a small fish called a mummichog (Fundulus heteroclitus) leaping into a flooded nest and attacking a hatchling seaside sparrow (Ammospiza maritima), demonstrating that baby sparrows in this habitat face a threat previously unknown to scientists.

Corina Newsome, an ornithologist at the Hunter Lab at Georgia Southern University in Statesboro, had placed cameras on the birds' nests to learn about the risks posed by predators. In this case, the predator came from an unexpected place: the water. 

"A lot of questions were spinning in my mind after seeing that," Newsome told Live Science.

Related: Beastly feasts: Amazing photos of animals and their prey

Tidal salt marshes in Georgia are home to many types of birds, and seaside sparrows that live there are known to build their nests in spots prone to flooding when the tide rises, Newsome and her co-authors reported Feb. 5 in The Wilson Journal of Ornithology. This can be hazardous for young chicks, though they often survive minor floods, according to the study.

But choosing a drier nesting site that's higher up can leave hatchlings more exposed to a number of predators, Newsome said. Bigger birds such as crows or grackles find baby sparrows delicious, as do raccoons, marsh rice rats and American minks; and sparrow chicks tend to be safer in nests that are closer to the ground, as this provides them with protective cover. 

Salt marshes are also inhabited by the hardy mummichog. These fish measure up to 3 inches (9 centimeters) long, are highly tolerant of adverse conditions, such as low levels of oxygen and dramatic temperature changes, and they feast on a variety of small aquatic animals, including snails, clams and other fish, the researchers wrote in the study.

A threat from below

On June 5, 2019, one of Newsome's cameras recorded some unusual activity in a flooded sparrow nest during high tide. The nest held two eggs and a chick that had hatched earlier that day.

"In the video, you can see the water rising incrementally in the nest, and the chick is floating on top of the water," Newsome said. Suddenly, a fish pops over the edge of the nest, resting briefly next to the floating hatchling — and then it strikes. The mummichog pulled the chick underwater and "thrashed the chick around in its mouth" until the nestling drowned, according to the study.

A flooded nest isn't necessarily an automatic death sentence for baby sparrows — if they can keep their heads above water and the water subsides before lowering their body temperature too much, even a newly hatched baby bird can survive a dunking. 

"But if they're having predators access the nest with the water, that presents an entirely new threat," Newsome said. Nothing like this had been previously reported by scientists, she added.

The encounter may have filled the mummichog's belly, but it left the researchers hungry for answers about this previously unseen danger. For instance, Newsome asked, how does the threat of nest predation vary between aquatic and terrestrial predators? Do sparrows build their nests to optimize their protection against one type of predator, only to end up more vulnerable to others? And are fish the only aquatic carnivores that take advantage of flooded nests, or do marsh turtles also snack on hatchlings during high tide? 

"A lot of research has been done to show that nest predation increases when the height of the nest off the ground increases," Newsome explained. "But this adds a layer of complication to what predation threat actually looks like for this species."

Originally published on Live Science.

Tangle-web spiders are eight-legged engineers, crafting silk pulleys to snag oversized prey like lizards or even small mammals walking on the ground below. 

Until now, scientists didn't know exactly how the arachnids were able to capture such hefty victims. For the first time, researchers analyzed the spiders' building techniques and silk construction for trapping and lifting heavy animals. 

Turns out, the spiders actively "tuned" their silk mechanisms once the prey was caught, attaching pre-stretched threads in pulleys to maximize their lifting power and elevate prey much heavier than the arachnids themselves, the researchers reported in a new study.

Related: 21 totally sweet spider superlatives

Spider silk is very good at dispersing energy; when an insect flies into a web, energy from its struggles gets absorbed and dissipated through the network of joined threads. The silk is also elastic, which enables it to store and amplify energy, much like the string on a bow that's pulled taut and then released to shoot an arrow. 

For the study, scientists questioned how tangle-web spiders might use the elastic in silk to do their heavy lifting, whenever their sticky trapping threads caught something too cumbersome for the spider to haul up from the ground.

There are more than 2,200 described species of tangle-web spiders (also called cobweb weavers) in the family Theridiidae. They live around the world and are known for their dense, irregularly-shaped webs, according to the biodiversity database Encyclopedia of Life (EOL). For the researchers' experiments, they worked with two tangle-web species — Steatoda paykulliana and Steatoda triangulosa — and tasked the spiders with lifting live orange-spotted roaches (Blaptica dubia). The spiders weighed 0.007 ounces (0.22 grams) at most, and the heaviest roaches weighed nearly three times that at 0.02 ounces (0.56 g).

"The trap changes"

In the experiments, the scientists observed the spiders as they built their snares, dangling special fibers studded with sticky glue to both ensnare prey and signal to the spider when something was caught. If the unlucky victim is a small insect, that one thread may be enough to lift it up, said lead study author Gabriele Greco, a postdoctoral researcher with the Laboratory of Bio-inspired, Bionic, Nano, MetaMaterials Mechanics at the University of Trento in Italy.

But if the prey is too big for the spider to yank up using the power of its own legs, "this is when the trap changes," Greco told Live Science. "The spider is getting involved, too." 

No longer a passive observer, the spider then starts producing hypertension threads — silk fibers that the spider stretches as it anchors one end to the web and attaches the other to the trapped prey. When the threads relax, they release their stored energy to incrementally raise the animal's weight, and the spider does this over and over again until the prey is at the desired height, Greco explained. In the experiments, the spiders hefted the heavy roaches as high as 3 inches (8 centimeters) off the ground, and their fastest lifting speed was about 0.004 inches (0.01 cm) per second, the researchers reported.

The study authors also described four different types of silk that the spiders used to construct the web, each with a specific function. There were two types of supporting threads, each produced by a different gland; "trapping" threads, coated with sticky droplets; and finally, a cement-like silk joining the threads together. The spider then produced a fifth type of silk to bind and immobilize its prey, Greco said. 

"The spider is a perfect factory of silk, it produces multifunctional materials in less than milliseconds — at least five different materials" he added.

Another type of arachnid — the triangle weaver spider (Hyptiotes cavatus) — also takes advantage of silk's ability to store and release energy; it uses its silk to craft stretchy slingshots that launch the spider much farther than it could travel by jumping, Live Science reported in 2019.

But there is much the researchers still don't know about spider silk elasticity, such as how much the silk can relax and stretch again. Calculating this limit would help scientists understand just how far a spider could stretch the tension threads, which also have to withstand the struggles of a captured animal without snapping or going limp.

"These were just the first insights in this direction," Greco said.

The findings were published online Feb. 3 in the Journal of the Royal Society Interface.

Originally published on Live Science.

When a dead thresher shark washed up onshore, it was obvious what had killed it — a swordfish had stabbed it from behind and left a large hunk of its "sword" embedded in the beast, a new study finds.

No one saw the actual attack, so it's unclear why the swordfish jabbed the shark. But the two ocean predators may have been competing for prey, the researchers said.

"The most likely scenario is that both species were hunting on a school of fish or on squids in the deep," said study lead researcher Patrick Jambura, a doctoral student in the Department of Paleontology at the University of Vienna. 

Related: 7 unanswered questions about sharks

It's also possible the two ocean predators were fighting over territory, or that the swordfish accidentally stabbed the thresher shark and left nearly 12 inches (30.1 centimeters) of its "sword" in the victim, he said. 

News of the fight's deadly aftermath spread when the shark's body washed up on the Mediterranean coast of Libya, near the town of Brega in April 2020. A local citizen scientist group learned about photos and video taken of the 14.5-foot-long (4.5 meters) dead shark, and after seeing the evidence "I was just stunned for a few moments," Jambura told Live Science in an email. Swordfish (Xiphias gladius) are known to defend themselves against blue sharks (Prionace glauca) and mako sharks (Isurus oxyrinchus), as these sharks prey on swordfish. 

Swordfish have also been reported attacking whales, sea turtles, inanimate objects, including boats and submarines, and even humans, Jambura and his colleagues wrote in the study. In 2015, "a diver was killed in Hawaii when he speared a small swordfish that had wandered into a marina," said Yannis Papastamatiou, a marine biologist at Florida International University, who was not involved in the study. "It speared him through the chest."

But thresher sharks (Alopias superciliosus) eat small fish "and wouldn't be a threat" to swordfish, Jambura said.

Whatever the reason for the stabbing, "we know that the swordfish attacked from above — the shark was most likely not even aware of the danger [it] was in until it was too late," Jambura said. It appears that the roughly 10-foot-long (3.1 m) swordfish stabbed the shark just behind the head, leaving a cut 2 inches (5 centimeters) deep and 3 inches (8 cm) wide where it pierced the shark's gill system. Because no one performed a necropsy (an animal autopsy), there's no way to know whether that caused deep internal damage, "but from the angle and the depth of penetration, it is safe to say that the gill region was heavily damaged, possibly also some important arteries," Jambura said.

While this is the first reported case of a swordfish killing a thresher shark, scientists don't know how often this happens in the water's depths. "We rarely see evidence of these outcomes: Sharks are negatively buoyant and will sink when they die," Papastamatiou told Live Science in an email. "Unless they wash up on the beach like here (which is rare, most will sink into the deep sea), then we won't find evidence of the interaction."

The swordfish left the altercation physically damaged, but that doesn't mean the fish died; there are known cases of billfish (a close relative of the swordfish) that have damaged, malformed or even missing rostra (or its pointy "sword") that "were apparently still in good physical shape," the researchers wrote in the study. Perhaps the assailant survived. 

The study was published online Oct. 7 in the journal Ichthyological Research. 

Originally published on Live Science.

Update, Dec. 17 at 2:40 pm EST: Live Science has learned that the animal dangling from the heron is an American eel (Anguilla rostrata), not a snake eel. American eels are common in Delaware waters and along the U.S. Atlantic coast, according to the Delaware Department of Natural Resources and Environmental Control (DNREC). "It is rare for a heron to swallow an American eel that big and even rarer for the eel to burst out of the heron," a DNREC fisheries biologist told Live Science.

The original story, posted Nov. 10, is below.

A snake eel fighting for its life pulled an "alien" move by bursting out of the stomach of a heron that had just swallowed it whole, according to photos snapped by an amateur photographer in Delaware.

The photos show the snake eel, its head dangling in midair, as the heron — looking surprisingly unbothered — flies onward.

The unusual event attracted a lot of attention among the local predators, said Sam Davis, an engineer from Maryland who took the photos on the Delaware shore. Several juvenile eagles and a fox were following the heron, possibly hoping to scavenge a meal in case the heron or the snake eel didn't make it, he said.

Related: 15 of the largest animals of their kind on Earth

When Davis first spotted the bizarre flight, he thought that a snake or eel had bitten the heron's neck. Davis was about 75 yards to 100 yards (68 to 91 meters) away from the animals, but he had a telephoto lens for long-range photography, and so he shot photos as he watched the heron fly about and even land in the water with the eel still attached to it. "The heron didn't seem to act much differently," Davis told Live Science. "It was in the water and flying around."

Meanwhile, the eel was arching its body, "so i guess it was still alive at some point," he said.

It wasn't until Davis returned home and edited the photos that he realized that the snake eel wasn't biting the heron. After enlarging the photos, "I could see the eel, you could see its eyes," he said. "It was actually coming out the other end" — headfirst.

The photos show "a pretty amazing sight," said John Pogonoski, an ichthyologist with the Australian National Fish Collection at the Commonwealth Scientific and Industrial Research Organisation (CSIRO), who wasn't involved with the heron and snake eel's encounter. "I would think this is either very rare or very rarely seen in a bird species, at least as far as I am aware."

Earlier this year, Pogonoski and his colleagues published a study in the journal Memoirs of the Queensland Museum on snake eels (a fish from the family Ophichthidae), detailing how snake eels can burrow out of the guts of fish that prey on them. "But usually they don't get very far," he told Live Science in an email. Once swallowed, snake eels can use their hard heads or tails to bust out of the digestive tract, but usually end up in the predator's body cavity, muscle tissues or swim bladder. Once trapped, snake eels often "become 'mummified' or 'encysted' [closed up in a cyst] and die rather than escape," he said. 

In one instance, "a co-author of the paper once discovered a live snake eel inside a fish he caught when he cleaned the fish to eat it," Pogonoski said.

Davis never learned what happened to the heron and snake eel photographed in Delaware in 2011 (he uploaded the photos to a wildlife site only a few months ago). When he left the shore, the heron was still flying around with the snake eel hanging below it.

According to Pogonoski, "the heron possibly survived, it didn't look too inconvenienced, but would depend on how well the wound healed and if it was able to avoid an infection."

As for the snake eel, it "would only have survived if it was dropped over or very close to water with a salinity it could normally tolerate," he said. 

Originally published on Live Science.

Pity the toads that encounter Asian kukri snakes in Thailand. These snakes use enlarged, knifelike teeth in their upper jaws to slash and disembowel toad prey, plunging their heads into the abdominal cavities and feasting on the organs one at a time while the toads are still alive, leaving the rest of the corpse untouched.

While you're recovering from the horror of that sentence, "perhaps you'd be pleased to know that kukri snakes are, thankfully, harmless to humans," amateur herpetologist and naturalist Henrik Bringsøe, lead author in a new study describing the gruesome technique, said in a statement.

This grisly dining habit was previously unknown in snakes; while some rip chunks from their prey, most snakes gulp down their meals whole. Scientists had never before seen a snake Bury its head inside an animal's body to slurp up organs — sometimes taking hours to do so, Bringsøe and his colleagues reported. 

Related: Beastly feasts: Amazing photos of animals and their prey

The victims of this horrific organ-slurping were poisonous toads called Duttaphrynus melanostictus, also known as Asian common toads or Asian black-spotted toads; they are stout and thick-skinned, measuring about 2 to 3 inches (57 to 85 millimeters) in length, according to Animal Diversity Web (ADW), a wildlife database maintained by the University of Michigan's Museum of Zoology. During the deadly battle, the toads fought "vigorously" for their lives, with some defensively secreting a toxic white substance, according to the study. The snakes' grisly evisceration strategy could be a way to avoid the toad's poisonous secretions while still enjoying a tasty meal, the researchers wrote.

Kukri snakes in the Oligodon genus are so named because their slashing teeth resemble the kukri, a forward-curving machete from Nepal. While kukri snakes aren't a threat to people, their teeth can cause painful lacerations that bleed heavily, because the snakes secrete an anticoagulant from specialized oral glands, according to the study.

"This secretion, produced by two glands, called Duvernoy's glands and located behind the eyes of the snakes, are likely beneficial while the snakes spend hours extracting toad organs," Bringsøe explained.

Macabre mealtime

The researchers described three observations in Thailand of kukri snakes (Oligodon fasciolatus), which can measure up to 45 inches (115 centimeters) long, consuming Asian common toads. In the first incident, which took place in 2016, the toad was already dead when the witnesses discovered the scene, "but the soil around the two animals was bloody, indicating there had been a fight which eventually killed the toad," the scientists wrote. The snake sawed through the toad's body by swinging its head from side to side; it then slowly inserted its head into the wound "and subsequently it pulled out organs like liver, heart, lung and part of the gastrointestinal tract."

In a second event, an epic battle between a kukri snake and a toad on April 22, 2020 lasted nearly three hours; the snake attacked, withdrew, and attacked again, deterred only temporarily by the toad's poison defense. After finally subduing the toad, the snake extracted and swallowed organs while the toad was still breathing, according to the study. 

On June 5, 2020, a kukri snake took a different approach and didn't disembowel the toad at all, instead devouring it whole. But in a fourth observation this year on June 19, the snake eviscerated its toad prey, slicing into the abdomen to reach its organ meal.

Young toads potentially produce less poison than adults do, which may have enabled the snake in the June 5 observation to safely gulp it down in one piece; another possibility is that kukri snakes are immune to the toad species' toxins, but they disembowel adults anyway because the toads are simply too big for them to swallow, the researchers reported. 

However, there's not yet enough data to answer these questions, Bringsøe said in the statement. 

"We will continue to observe and report on these fascinating snakes in the hope that we will uncover further interesting aspects of their biology," he said.

The findings were published online Sept. 11 in the journal Herpetozoa.

Originally published on Live Science.

About 240 million years ago, one giant sea monster ate another, and then died with chunks of the beast in its belly. Researchers in China have now discovered and analyzed the fossilized corpses of these beasts, which they are calling the oldest evidence of megapredation — when one large animal eats another — on record. 

It remains a mystery, however, exactly how the larger predator — an ichthyosaur, a dolphin-like marine reptile that lived during the dinosaur age — came to feast on the slightly smaller sea monster, a thalattosaur, a fearsome lizard-like marine reptile that lived during the latter part of the Triassic period. 

The ichthyosaur may have attacked and killed the thalattosaur before eating it, but it's also feasible that the ichthyosaur was simply scavenging the thalattosaur's remains, the researchers said.

Related: Image gallery: Ancient monsters of the sea

Whatever happened, the ichthyosaur, likely a new species from the genus Guizhouichthyosaurus, never took another bite. "It is most likely that the thalattosaur was its last meal, given that the prey had poorly been digested when the predator died," study co-lead researcher Ryosuke Motani, a paleobiologist at the University of California, Davis, told Live Science in an email. 

Researchers found the remarkable fossil in the fall of 2010, while digging at a quarry in the Falang Formation in the southwestern province of Guizhou, China. "We could see a small piece of the fossil hidden in the hill" and realized that "it must be from a large ichthyosaur," study co-lead researcher Da-yong Jiang, a paleobiologist at Peking University in Beijing, China, told Live Science in an email. 

As the researchers prepared the nearly 16-foot-long (4.8 meters) specimen to study, they realized it held the bones of the ichthyosaur's last meal bulging out of its abdomen. 

"Finding any animal other than fish or squid in an ichthyosaur's stomach contents is incredibly rare (in fact, finding fish/squid in an ichthyosaur stomach is also quite rare); only a handful of other different types of animal have been found inside an ichthyosaur's stomach, as food," Dean Lomax, a paleontologist and visiting scientist at the University of Manchester in England, who wasn't involved with the study, told Live Science in an email. 

"The discovery of a fairly large (4.8 m) ichthyosaur with a comparatively very large (4 m) thalattosaur dinner is highly unusual," Lomax added. 

The head and tail of the more slender thalattosaur, identified as Xinpusaurus xingyiensis, were not swallowed by the ichthyosaur, so it appears that the ichthyosaur took four enormous bites of the thalattosaur's midsection, based on the pieces the researchers found in the predator's abdomen. 

Related: The 10 weirdest sea monsters of 2017

About 80 feet (25 m) away from the Guizhouichthyosaurus, the researchers found the fossil of a Xinpusaurus tail that might belong to the same Xinpusaurus that ended up in the ichthyosaur's stomach. "If this is correct, then it might suggest that the predator had 'bitten off more than it could chew,' so to speak, in that it was a much larger meal than it had anticipated, and which could have led to its downfall," Lomax said. 

Researchers often guess what ancient predators ate by analyzing their tooth shape and body size. Surprisingly, this genus of ichthyosaur, which usually measured between 13 and 20 feet (4 and 6 m) long, or just smaller than a killer whale (Orcinus orca) — was not previously thought to be an apex predator. 

"This predator did not have a typical dentition of the top predator — its teeth look like they are good for grasping squids," Motani said. "So, it was a surprise to find such large prey" in its stomach. The finding changes the view of other large reptiles with teeth like Guizhouichthyosaurus's. They "may have also been megapredators, although we did not consider them as such before," Motani said. 

In other words, fierce megapredators didn't necessarily need sharp, slicing teeth to be dangerous, Motani noted. Perhaps Guizhouichthyosaurus used its blunt teeth to grip prey, possibly breaking the spine with the force of its strong bite, just as modern apex predators such as orcas, leopard seals and crocodiles do today, the researchers said.

"This study has compelling evidence that we are underestimating the number of megapredator taxa in marine ecosystems," said Eric Metz, the manager of a paleobiology laboratory at Montana State University, who wasn't involved with this study. 

Because megapredators rely on a vast food chain beneath them for survival, their prevalence can reveal whether an ecosystem was doing well. For instance, earlier research on the end-Permian mass extinction, which killed more than 96% of marine and 70% of land animals about 252 million years ago, used the presence of megapredator fossils to show when ecosystems had recovered. 

If paleontologists have been undercounting megapredators, "This could have an impact on our understanding of the recovery rate of marine ecosystems following the Permian mass extinction event," Metz said.

The study was published online today (Aug. 20) in the journal iScience.

Originally published on Live Science.

A Triassic-aged sea monster with "a very long broomstick for a neck," sharp curved teeth and a crocodile-like snout wasn't a prima donna; rather, this reptile shared Pangaea's coastal waters with another long- and stiff-necked beast — one that was so similar-looking, scientists used to think the two predators were the same species. 

Now that it's clear that these giraffe-like reptiles are two distinct species, scientists chose to name the larger of the two Tanystropheus hydroides, a nod to the hydra, the long-necked mythical sea monster of Greek antiquity. The smaller one kept the preexisting name, Tanystropheus longobardicus.

It's rare for two animals with such peculiar necks — which were not just long but also fairly inflexible — to live in the same place simultaneously, the researchers said. But T. hydroides and T. longobardicus somehow found a way to coexist when they were alive about 242 million years ago, mainly by hunting different animals so they didn't have to compete for food, according to an analysis of their teeth and earlier analyses of T. hydroides' stomach contents.

"They had evolved to feed on different food sources with different skulls and teeth, but with the same long neck," study lead researcher Stephan Spiekman, a former doctoral student at the University of Zurich's Paleontological Institute and Museum in Switzerland, told Live Science in an email.

Related: Image gallery: Photos reveal prehistoric sea monster

Paleontologists first described Tanystropheus in 1852, but have struggled since then to make sense of its strange anatomy. The Italian paleontologist Francesco Bassani (1853-1916) thought Tanystropheus was a flying reptile called a pterosaur, and that its long hollow neck bones were actually finger bones that supported its wings. This hypothesis was later debunked when scientists realized that the 20-foot-long (6 meters) reptile had a 10-foot-long (3 m) neck that was three times the length of its torso. 

Smaller, 4-foot-long (1.2 m) fossil specimens found in the same Triassic period outcrops were thought to be juveniles of the same species, said study co-researcher Olivier Rieppel, the Rowe Family Curator of Evolutionary Biology at the Field Museum in Chicago. 

Curiously, these big and small reptiles each had only 13 elongated neck vertebrae, some of which were reinforced with extra bones known as cervical ribs, making their necks relatively stiff. In contrast, the Triassic long-necked reptile Dinocephalosaurus had upwards of 30 neck vertebrae, and the sauropod dinosaurs had up to 19 neck vertebrae. The additional vertebrae gave these animals more cervical flexibility than Tanystropheus had, Rieppel said.

"Why such a neck? That has always been the question," Rieppel said. Some paleontologists thought it survived in spite of its neck. But the genus Tanystropheus, which includes several other long-necked species such as T. conspicuus and T. antiquus, did quite well for itself, surviving roughly 14 million years, from about 248 million to 234 million years ago. Soon, paleontologists began wondering whether Tanystropheus survived not in spite of, but because of its neck, Rieppel said.

Given that so many of these species had stiff, long necks, it's likely that "this strange anatomy of Tanystropheus was ecologically much more versatile and adaptive than had previously been thought," Rieppel said.

While it's anyone's guess exactly how the two Tanystropheus species used their necks, one idea is that it helped them hunt. Tanystropheus have small heads at the end of their long necks. "My best guess is that this would make this head quite difficult to see for its prey, especially in somewhat turbid water," Spiekman said. "This way, Tanystropheus, both the small and large species, were able to approach their prey closely without getting spotted and without having to be particularly good swimmers."

Once that prey was close enough, "it would simply snap at its prey to catch it," Spiekman said. Or, maybe Tanystropheus had a fleshy lure that didn't fossilize (soft tissues rarely do), but which helped it attract prey, much like how the snapping turtle uses its tongue as a lure, he said. 

Stiff necks

Tanystropheus resembled a monitor lizard, "but with a very long broomstick for a neck," said Spiekman, who will be a postdoctoral researcher at the Natural History Museum in London this October. However, many large Tanystropheus fossils are crushed, so they're hard to decipher. Scientists couldn't even agree if it was land dwelling or sea faring. 

So, the researchers of the new study CT scanned the skull of a big Tanystropheus specimen from the Swiss-Italian border, which allowed them to assemble 3D digital images of its skull. The scientists also studied both creatures' cranial anatomies, and they sliced through some of the fossilized bones of two smaller Tanystropheus individuals, so they could see the creatures' growth rings, which are like the rings of a tree. 

Related: Photos: Early dinosaur cousin looked like a croc

The researchers focused on the skulls because "other than size, there's basically no difference in the skeleton between the two species," Spiekman said. "But the skulls are, of course, very different as they are adapted to deal with different food sources."

Tanystropheus had nostrils on top of its snout like a crocodile, suggesting it lived in the water. The larger T. hydroides was likely an ambush predator that waited for fish and squid-like animals to swim by before it grabbed them with its long, fang-like teeth. It's still unclear whether the larger beast laid eggs on land, like a turtle, or had live births in the water like other Triassic reptiles, such as the ichthyosaur. 

An analysis of the smaller Tanystropheus' growth rings revealed that it was fully grown. Taken together with its unique skull anatomy and teeth (the smaller Tanystropheus had cone-shaped teeth while the larger one had crown-shaped chompers), the researchers concluded that the smaller Tanystropheus wasn't a juvenile, but the separate species T. longobardicus. 

Despite their shared long necks and habitats in Pangea's Tethys Sea, these two Tanystropheus species had different lifestyles. The smaller T. longobardicus likely ate small shelled animals, such as shrimp, while the larger T. hydroides gulped down fish and squid.

"The neck of Tanystropheus looks very awkward to us," Spiekman said. "But Tanystropheus was not a weird evolutionary 'mistake,' as was previously thought. Instead, it was in terms of evolution a very successful animal because of its neck, and not despite of it."

The study was published online today (Aug. 6) in the journal Current Biology. 

Originally published on Live Science.

New slow-motion video shows how praying mantises snatch their prey with lightning-fast, deadly precision.

Though these strikes are completed in microseconds, the long-armed predators calibrate their attacks even more quickly than that, adjusting to prey's speed and movements; praying mantises can even halt mistimed attacks mid-strike, scientists reported in a new study.

Related: Lunch on the wing: Mantises snack on birds (photos)

Mantises are ambush predators; rather than stalking or chasing their prey, they select a perch and then wait, motionless, their spike-studded arms folded and ready. When an unsuspecting victim wanders too close, the mantis lunges and grabs, holding tight to the prey's wriggling body. The mantis then begins to feed on its living victim almost immediately.

This type of sit-and-wait approach was long thought to be mostly one-size-fits-all, with predators using the same technique over and over again, said lead study author Sergio Rossoni, a doctoral candidate in the Department of Zoology at the University of Cambridge's Clare College, in England.

"This is because a lot of famous sit-and-wait predators use attacks, which rely on a loaded spring (like a jack-in-the-box toy), such as the projectile tongue of frogs, or the loaded punch of mantis shrimps," Rossoni told Live Science in an email.

"The assumption was that a spring needs to be loaded with a set force in order to spring back, leaving little room for variability," he explained. 

But Rossoni and his co-author Jeremy Niven, a senior lecturer at the University of Sussex in England, suspected that mantises' ambush attacks could be more flexible. The scientists put that to the test by observing and documenting the hunting habits of Madagascan marbled praying mantids (Polyspilota aeruginosa), creating enclosed "arenas" for their mantises; offering them small insects or tiny beads as attack targets; and filming the mantis strikes at 200 frames per second. 

Huge variation

The researchers then reviewed and analyzed the slow-motion footage. They found that the speed of the strikes varied greatly, with some taking just 60 milliseconds (a millisecond is one-thousandth of a second), and some lasting nearly five times as long, up to 290 milliseconds. The speed of the mantises' strikes changed in response to the speed of the moving prey, according to the study. 

Even more surprising was that the mantises would sometimes "pause" mid-strike, either to correct an attack if they moved too soon, or to abandon an ill-timed move before they caught their prey — a behavior that had never been described before in these big insects, Rossoni said. 

This suggests that mantids monitor the timing of their attacks and calculate the speed and trajectory of their prey to pinpoint precisely when they should snatch it, the researchers found. However, that doesn't mean that the insects are adding up numbers in their tiny heads, Rossoni said. 

"I'm not suggesting that they can do maths, just like humans do not consciously calculate the speed of a moving ball when trying to catch it. But the mantid's nervous system is somehow capable of transforming visual information about prey into a well-timed sequence of motor output," he explained. 

"For a brain as small as an insect's, that's quite formidable! So, we would like to understand how the mantid's nervous system is capable of this, with future research," Rossoni said.

The findings were published online May 13 in the journal Biology Letters.

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Originally published on Live Science.

D.C. Comics' manic pixie criminal Harley Quinn gets it: Hyenas are delightful.

In the movie "Birds of Prey (and the Fantabulous Emancipation of One Harley Quinn)" (2020, Warner Bros. Pictures), Ms. Quinn (Margot Robbie) acquires some new partners in crime, including a large and very intimidating hyena that she bestows with a pink collar and names Bruce — "after that hunky Wayne guy," Quinn says.

While hyenas are ill-suited to be pets in real life, they are nonetheless fascinating animals that have complex social lives and astounding physical capabilities that even a supervillain would envy. 

Here are just a few of the reasons why we think hyenas are awesome.

Related: Image gallery: Hyenas at the kill

They communicate using 'butter' from their butts

While hyenas do share messages with their signature cackle, some of their most important communications are generated at their other end. They produce a sticky, smelly secretion in their anal glands, and they smear it on grasses to send signals to other hyenas.

This malodorous paste — known as "hyena butter" — smells similar to wet mulch or cheap soap, Kevin Theis, an ecologist at Wayne State University in Michigan, previously told Live Science. Its distinctive scent is actually the product of bacterial communities that inhabit hyenas' scent glands, and changes in the bacteria can affect the "messages" that hyenas are sending with their butts, Theis explained.

They are 'incredible bone-crushing machines'

Hyenas' skulls and jaws are so powerful that they can crush the leg bones of large animals such as wildebeests and rhinos, according to Jack Tseng, an assistant professor with the Department of Pathology and Anatomical Sciences at the University at Buffalo in New York. 

Tseng studied the bone-crushing abilities of hyenas by scanning their skulls and creating computer models to calculate their bite force and tooth structure, he said in an animated video describing his research. 

However, not all hyenas have strong jaws. One notable exception is the aardwolf (Proteles cristata), a hyena species that feeds primarily on termites, Oliver Höner, a senior researcher at the Leibniz Institute for Zoo and Wildlife Research in the Department of Ecology, and co-founder of The Ngorongoro Hyena Project, told Live Science in an email.

Ancient hyenas dined on human relatives

Early humans once competed with ancient hyenas for space and resources — and sometimes humans ended up on the menu.

Tooth marks and cracks crisscrossed a femur found in a Moroccan cave and dating to around 500,000 years ago, and the marks suggest that a large carnivore, likely a hyena, chewed on the bone. Other bones in the cave belonged to the hominin Homo rhodesiensis, an extinct lineage of early humans, but it is unknown if the ancient hyena killed its hominin prey or scavenged the remains.  

By looking at coprolites, or fossilized dung, scientists have also found evidence that hyenas ate our human relatives. In 2009, researchers discovered dozens of animal hairs preserved in hyena coprolites from South Africa that dated to 200,000 years ago; an analysis revealed that humans — early Homo sapiens or our close relative Homo heidelbergensis — were the closest match for the tiny hairs.

They are better at cooperating than chimpanzees

Scientists discovered that hyenas can work together to get a reward, and they collaborated more readily and required less preparation than chimps or other primates did in similar experiments.

Researchers tested captive pairs of spotted hyenas (Crocuta crocuta) with a rope-tugging challenge: The hyenas received a food reward if they pulled two ropes at the same time. Not only did the hyenas cooperate to succeed at the task, they did so with no prior training and mostly without vocalizing — they watched and learned from each other in near-complete silence.

"The first pair walked in to the pen and figured it out in less than two minutes," said Christine Drea, an evolutionary anthropologist at Duke University in North Carolina who led the experiments. "My jaw literally dropped," Drea said.

They once ranged as far north as the Arctic

Today, hyenas are found only in Africa. But their ancestors first appeared about 20 million years ago, in Europe or Asia, and some of those ancient predators crossed into North America over the now-submerged Bering Strait land bridge, according to a pair of fossil teeth dating between 1.4 million and 850,000 years old that place the extinct hyena Chasmaporthetes as far north as the Arctic, in Canada's northern Yukon Territory.

These wolf-size hyenas vanished from North America between 1 million and 500,000 years ago, perhaps due to competition from ice age carnivores such as the giant short-faced bear Arctodus and the bone-cracking dog Borophagus. 

Chasmaporthetes is just one of around 100 species of hyenas that are known from the fossil record, according to a study published in 2005 in the journal Molecular Biology and Evolution. Today, there are only four hyena species: spotted hyenas (Crocuta crocuta), striped hyenas (Hyaena hyaena), brown hyenas (Parahyaena brunnea) and aardwolves (Proteles cristatus).

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Originally published on Live Science.

Paleontologists in Poland recently unearthed the jaws and teeth of a monstrous pliosaur, an ancient marine reptile with a bite more powerful than that of Tyrannosaurus rex.

Pliosaurs, the biggest of the Jurassic period's ocean predators, lived around 150 million years ago. Researchers found fossils of this enormous carnivore in a cornfield in the Polish village of Krzyżanowice in the Holy Cross Mountains, along with several hundred bones of crocodile relatives, ancient turtles and long-necked plesiosaurs — cousins of pliosaurs — according to a new study. 

Jurassic pliosaur fossils have been found in only a few European countries, and this is the first time bones of the massive marine predator have emerged in Poland, lead study author Daniel Tyborowski, a paleontologist with the Polish Academy of Sciences' Museum of the Earth in Warsaw, said in a statement.

Related: Image Gallery: Ancient Monsters of the Sea

A limestone block found at the site in Poland held cone-shaped teeth and fragments of an upper and lower jaw that the scientists identified as belonging to a pliosaur, dating between 145 million and 163 million years ago. The biggest tooth measured about 3 inches (68 millimeters) from crown to tip. Another large, isolated tooth — also thought to belong to a pliosaur — measured about 2 inches (57 mm) in length, according to the study.

Pliosaurs lived alongside dinosaurs (though not T. rex, which didn't appear until around 70 million to 65 million years ago, during the Cretaceous period). "They measured over 10 meters [32 feet] in length and could weigh up to several dozen tons," Tyborowski said in the statement. "They had powerful, large skulls and massive jaws with large, sharp teeth. Their limbs were in the form of fins." Unlike plesiosaurs — which had long, graceful necks and small heads — pliosaurs had massive heads  supported by thick, powerful neck muscles that helped them crush the bones of large prey.

One known pliosaur species, Pliosaurus funkei, had a 7-foot-long (2 m) skull and a bite estimated to be about four times as powerful as that of T. rex. These apex predators would have been at the top of the food chain in their marine ecosystems, feasting on crocodilians, plesiosaurs, turtles and fish, the study authors reported. Six pliosaur species have been described to date. However, it is not yet known to which species the new fossils belong.

"We hope that the next months and years will bring even richer material in the form of bones of large reptiles," Tyborowski said in the statement.

More than 100 million years ago, this mountainous region was an archipelago of islands surrounded by warm lagoons, but the variety of Jurassic marine species at the mountain site also suggested that this area was a "hub" where the habitats of different groups of marine reptiles overlapped, the scientists reported. 

Ancient turtles and crocodile relatives are known from Mediterranean sites; they inhabited warm waters in the Tethys Ocean, a vast sea that lay between two ancient supercontinents — Gondawna in the south and Laurasia in the north — during the Mesozoic period, 251 million to 65.5 million years ago. But pliosaurs, plesiosaurs and ichthyosaurs (another type of marine reptile with long, slender jaws) are more commonly found in cooler waters farther north. Because the site in Krzyżanowice holds fossils from both warmer and cooler environments, the researchers proposed that it represents a transitional zone that was once a unique ocean ecosystem, according to the study. 

The findings were published online Oct. 6 in the journal Proceedings of the Geologists' Association.

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Originally published on Live Science.

A recent confrontation between an elephant and a crocodile ended in a surprising twist that left both combatants dead, with the crocodile flattened underneath the fallen pachyderm.

A photo that was captured in Zambia's South Luangwa National Park by a guide with Kafunta Safaris showed the grim and surprising scene: A dead elephant lay on top of an equally dead crocodile, the reptile's long tail extending beyond the elephant's splayed hind legs. Other photos of the gruesome scene show dozens of vultures and other scavengers crowding around the carcasses. 

The safari company shared images of the remains on Facebook, calling the death poses "extremely strange." But what may have led to this highly unusual tableau?

Related: Beastly Feasts: Amazing Photos of Animals and Their Prey

Safari guide Andrew Mwanza discovered the carcasses on Oct. 8 on a bank of the Luangwa River near one of Kafunta Safaris' campsites, a company representative told Live Science in an email. Accompanying Mwanza at the time were several safari guests and an armed scout from Zambia's Department of National Park and Wildlife (DNPW). 

The dead elephant and crocodile both appeared to be young individuals, based on their body sizes; a later inspection by the DNPW and officials with Conservation South Luangwa ruled out poaching as the elephant's cause of death, as there were no bullets found in the body, according to the email.

Nile crocodiles (Crocodylus niloticus) are plentiful in the Luangwa River, and they often prey on elephants that come to cross the river or to drink from the water's edge, the representative said. Adult crocodiles can grow to be 20 feet (6 meters) long and can weigh as much as 1,650 lbs. (748 kilograms), according to National Geographic. By comparison, an adult African elephant (Loxodonta africana) weighs between 5,000 and 14,000 lbs. (2,268 and 6,350 kg), so crocodiles typically avoid attacking healthy adult elephants, said Marisa Tellez, co-founder of the Crocodile Research Coalition with the Marine Science Institute at the University of California in Santa Barbara.

"From the pictures I've seen, the croc was a small subadult or small adult, and I highly doubt it was trying to take an injured adult elephant down. That seems like a lot of work for a smaller predator, and not in its favor," Tellez told Live Science in an email. "Of course, you will always have more bold individuals that will take more than they bargained for," Tellez added. "I am also wondering if this may have been a young female defending her nest from an elephant possibly trampling all over it."

In general, crocodiles are more likely to target elephants that are young, ill or injured. The dead elephant in the photo was probably sick or hurt — "maybe previously attacked by lions" — when it encountered the crocodile, said the representative.

Crocodiles are ambush predators, and when they lunge at an elephant they usually grab its vulnerable trunk, said Agata Staniewicz, a crocodile researcher and doctoral candidate with the Behavioural, Acoustic and Sensory Ecology Lab at the University of Bristol in the United Kingdom.

"A healthy adult (sometimes with the assistance of the herd) can usually fight off the crocodile, though it may sustain severe injuries to the trunk," Staniewicz told Live Science in an email. "However, an injured or sick elephant might not have been strong enough to fight."

After struggling with the river predator, the elephant may have simply collapsed from its injuries or from exhaustion, and as it fell it landed on the reptile and crushed it to death, the Kafunta Safaris representative said. 

Although this story had an unhappy ending for the elephant and crocodile, plenty of nearby scavengers were clearly thrilled with the outcome, Kafunta Safaris representatives wrote on Facebook.

"All this made for a huge and happy meal for dozens of vultures," the representatives said.

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Originally published on Live Science.

Birds that live on land were recently found for the first time in a very unexpected place: the stomachs of sharks.

In 2010, biologists surveying populations of tiger sharks (Galeocerdo cuvier) along the coasts of Mississippi and Alabama were surprised when one of their shark subjects regurgitated some unusual feathers that did not resemble those from a seabird.

Visual and DNA analyses revealed that the feathers were from a ground-dwelling brown thrasher (Toxostoma rufum), the scientists reported in a new study. Over the next eight years, the scientists examined the stomach contents of 105 tiger sharks. The researchers found that songbird-eating happened far more frequently than expected, identifying 41 sharks that had eaten terrestrial birds — 11 species in all, including barn swallows, wrens, sparrows and meadowlarks. [8 Weird Facts About Sharks]

Nearly half of those bird-eating sharks were youngsters, according to the study.

It's not unheard of for both juvenile and adult tiger sharks to eat seabirds such as gulls and pelicans, though those birds typically make up only a small percentage of the sharks' diets, lead study author J. Marcus Drymon, an assistant extension professor at Mississippi State University's Coastal Research and Extension Center, told Live Science in an email.

But how were the sharks catching songbirds, which live on land? The sharks' avian prey were likely blown out to sea by storms during seasonal migrations, the scientists wrote. Seabirds can easily alight on the ocean surface and take off again, but exhausted and soggy songbirds would flounder. That would make them easy targets for even very young sharks that weren't experienced hunters. [See Photos of Baby Sand Tiger Sharks]

Some of the songbird remains were easy to identify by sight, but in many cases, the scientists dredged up lone and bedraggled feathers from the tiger sharks' bellies. To identify those outliers, the researchers turned to a technique called DNA barcoding, which looks at a small section of the genome — much like a barcode — to identify a species, said study co-author Kevin Feldheim, manager of the Pritzker Laboratory for Molecular Systematics and Evolution at the Field Museum in Chicago.

To isolate the feathers' genetic material from the slurry of "fish goop" and other stomach contents, Feldheim sliced into the feather shaft and extracted DNA, he told Live Science. Some of the feathers were already too digested for scientists to identify them, but about half of them provided enough DNA to pinpoint the owners, Feldheim said.

When songbirds migrate, powerful storms that force the birds from the skies can kill thousands of the animals, according to the study. "These weather events, while lethal for the birds, provide unique scavenging opportunities for tiger sharks," the scientists reported.

The findings were published online today (May 21) in the journal Ecology.

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Originally published on Live Science.

In lakes around the world, fearsome creatures attack with strikes that were recently found to be among the fastest in the animal kingdom.

High-speed footage showed the nightmarish swimmers in action; multiple-jointed mouthparts extended from their heads, revealing branching structures to catch and hold squirming prey — even when the prey sprouted "teeth" from its neck.

Fortunately for humans, these predators are positively puny, measuring just a fraction of an inch. They are the young of tiny flies in the Chaoborus genus; also known as phantom midge larvae or glassworms, they are so-named for their transparent bodies. And when researchers turned special cameras on the tiny phantom midge larvae, they discovered that the creatures' deadly attack was among the fastest seen in animals. [Tiny Grandeur: Stunning Photos of the Very Small]

Atop a glassworm's see-through body, its head is "a complex catching basket" tipped with an array of appendages for quickly trapping small crustaceans, scientists reported in a new study. 

Using high-speed video and computed X-ray tomography (CT) scans, the researchers recorded glassworms as they caught water fleas. The scientists then built 3D computer models of the "basket" of structures on the glassworms' heads, identifying grasping antenna, bristly "knife hairs," powerful mandibles and a finger-shaped structure tipped with bristles and spiky "thorns."

When a water flea floated close by, the waiting glassworm would strike, its "basket" opening outward and then quickly contracting, pushing the flea toward the glassworm's waiting mouth. The tiny predator would stuff the water flea into its esophagus, using alternating movements of its jaws; while this "chewing" action didn't seem like it was meant to shred the water fleas, they would sometimes burst from the friction, according to the study.

A glassworm's average strike lasted about 14 milliseconds (a millisecond is one-thousandth of a second) "from start of movement to prey contact" — one of the fastest attack moves in animals, the researchers wrote.

By comparison, the attack of the praying mantis Coptopteryx viridis takes 42 milliseconds (ms). Scientists have also recorded phenomenally speedy strikes in mantis shrimp (4 to 8 ms) and in trap-jaw ants and some trap-jaw spiders (less than 1 ms), according to the study.

Despite the phenomenal speed of the glassworms' strike, water fleas aren't defenseless; special "neck teeth" pop out under their heads when a threat appears. When water fleas did not deploy their teeth, glassworm attacks succeeded approximately 80 percent of the time. However, if water fleas displayed their spiky necklace of teeth, glassworms captured only around 50 percent of their prey, the scientists reported.

The findings were published online March 22 in the journal PLOS ONE.

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Originally published on Live Science.

For small animals in the tropics, spiders and their arthropod cousins are responsible for "a surprising amount of death," scientists recently discovered.

Researchers captured gruesome photos of the spiders' hunting prowess in the Peruvian Amazon, revealing in a new study that the arachnids regularly dine on frogs, fish, lizards and even small mammals.

Large tropical spiders are known to hunt vertebrates — animals with backbones — but this is the first study to collect observations of these predators in a region over time. The scientists also recorded the first evidence of a tarantula clutching one particularly unexpected victim: a young mouse opossum (Marmosops noctivagus) that was about the same size as the spider, a species in the Pamphobeteus genus. [In Photos: A Tarantula-Eat-Snake World]

Spiders and other arthropods that prey on vertebrates tend to have special adaptations to subdue their wriggly, muscular dinners, such as modified jaws, enlarged chelicerae — claws in front of their mouths — and powerful venom, the researchers wrote in the study.

Photos taken by the researchers documented multiple species of spiders and other arthropods (a group that includes spiders, insects and crustaceans) — such as a giant water bug and several centipede species — as they sank their mandibles deep into their prey. The study authors described 15 interactions captured in night surveys that took place during expeditions to southeastern Peru's Madre de Dios region in 2008, 2012, 2016 and 2017, according to the study.

"In a single night survey, it's fairly common to see between three and five predator-prey interactions," lead study author Rudolf von May, a postdoctoral research fellow in the Department of Ecology and Evolutionary Biology at the University of Michigan (UM), told Live Science in an email.

"The most common interaction we see is spiders eating other invertebrate prey such as crickets and moths," von May said. But vertebrate prey was also on the menu, the scientists reported. In one instance, a centipede was consuming a juvenile snake while it was still alive (the scientists humanely euthanized the snake after the centipede abandoned it).

These observations suggest that arthropods are "a major source of mortality" for small vertebrates, said study co-author Dan Rabosky, an associate professor of herpetology at UM and a curator at the UM Museum of Zoology.

Why does that matter? Scientists need a clear picture of how species interact in order to understand and protect fragile ecosystems that are increasingly at risk from human activity and climate change, Rabosky said.

"We're trying to collect data as frantically as we can to at least get a snapshot of what's going on now, so we can understand future impacts," he said.

The findings were published online today (Feb. 28) in the journal Amphibian and Reptile Conservation.

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Originally published on Live Science.

Any other name

There is no animal across the Americas that has been given more names than the hemisphere's dominant hunting cat often known as the mountain lion, Puma concolor — which translates to "lion of one color," referring to the adult mountain lion's beautiful tan-colored coat. Regardless of their regional names, these magnificent predators are the second largest member of the cat family in the Americas (jaguar takes the top slot) and the fourth largest cat found in the world.

Tough critters

These large American cats once had a home range spanning over 110 degrees in latitude, thriving from the far northern Canadian Rockies to the Straits of Magellan and from the Atlantic Ocean to the Pacific Ocean. Only man has ever had as wide a distribution. The native people of both North and South America had their special name for the cats found in their cultural area, and the many European explorers added to the names used for these graceful cats. Etymologists contend that the mountain lion has more than 16 different names among the native people of South America, 25 names among the native people of North America and some 40 different English names. If you look up the name "mountain lion" in a current dictionary, you will find a listing of more names for this creature than any other animal in the world.

Long heritage

Whether called a mountain lion or a catamount, puma, panther, cougar, painter, gato monte or el leon, this indigenous American cat has ancestors that crossed over the Bering Land Bridge from Asia during the Illinoian glacial stage some 191,000 to 130,000 years ago and has always been one of the America's apex predators.

Beautiful and unique

Male mountain lions can grow to be 8 feet (2.4 m) long from nose to the tip of their tail and weigh upwards of 220 pounds (100 kilograms). Females only grow upwards to 7 feet (2.1 m) in length and 140 pounds (64 kg) would be considered a large female cat. A beautiful tawny-beige fur covers the cats' bodies, except for the belly and chest, which is a grayish-white. The tips of the tail, ears and around the snout are highlighted with black fur. Mountain lions are unique to the large cat family in that they cannot roar, but they can make a series of shrieks, growls, hisses and even will purr like the domestic house cat.

Big foot

Mountain lions have a distinctive M-shaped foot pad with three lobes on the rear heel pad. When walking, their claw marks do not show up as part of their track marks. Since their toes slant, like the human foot does, they too have definite left and right feet. When walking, their back feet step into the track of their front feet creating an overlapping pattern of tracks.

Solitary creatures

Biologists have long thought that male and female mountain lions tend to live a solitary lifestyle, except during mating season. Both sexes are extremely territorial, marking their territories with pheromones, feces and claw marks. An adult male mountain lion's territory is usually more than 100 square miles (2,592 square kilometers) in size, while a female's territory is smaller, ranging from 20 to 60 square miles (52 to 1,552 square km). Mountain lions can move through their territories at speeds approaching 10 mph (30.6 km/h).

Quick on their feet

Deer are the mountain lion's prime prey animal. Wherever deer are found, there is a good chance that mountain lions are nearby. Mountain lions thrive best in regions of steep, rocky canyons and/or mountainous terrain, but they can adapt to make their homes everywhere from arid deserts to coastal forests. They can live at elevations from sea level to 10,000 feet (3,048 meters). Their powerful legs can propel them as high as 15 feet (4.5 m) into the air, allow them to leap forward some 40 feet (12 m) and burst into a short hunting sprint at a speed nearly 50 mph (80 km/h).

Meat eaters

Mountain lions are carnivores and often travel great distances in search of food. In addition to deer, mountain lions will eat a variety of other mammals, including raccoons, mice, squirrels, rabbits, porcupines, beavers and coyotes. They will eat just about any mammal that crosses their path. They nearly always stalk their prey and attack from behind. They attempt to break the neck of their prey by biting the victim at the base of the skull. After the kill, the mountain lion will often bury the prey, returning to feed upon it when hungry.

Cutie-patooties

Mountain lion breeding season is commonly December to March, but these large cats can and do breed any time of year. Gestation usually lasts from 82 to 96 days. The mother cats generally give birth to two kittens, but female lions have been known to have litters ranging in number from one to six.

The young normally stay with their mother for about 14 months, but can stay for upwards of 26 months. Female mountain lions raise the young alone, as the male takes no parenting role and could kill the young kittens in order to encourage the female to mate again. The fur of the young is spotted to aide in camouflaging. The spots fade as the young mountain lions mature.

Too comfy

Urban mountain lions have become more common around the cities of the American West. Some biologists suggest that females bring their kittens closer to the cities to escape potential danger from male lions. Others suggest that as the deer population became more urban, the mountain lions simply followed the deer. Living near humans has many hazards for the female lions and her kittens, as the large cats are never welcome into a neighborhood of human children, livestock and pets.

Losing home

Mountain lions were once hunted to extinction along the east coast of the United States, except in Florida; and all mountain lions seem to have a natural avoidance of human contact. Since these large cats have a most elusive nature, biologists have had a tough time counting them or even studying them. Unwelcome by humans and extensive loss of habitat makes living in the wilds of North America challenging for these large predators. Biologists suggest that a free-roaming mountain lion in the wild will live only 10 years, while those in captivity can live nearly 20 years. Best estimates today suggest that there are some 30,000 mountain lions across North America, mostly living in the rugged regions of the American West. The natural habitats of these mountain lions are under extreme pressure from human development.

Learning more

RRecent research at the University of California, Berkley, suggests that mountain lions are far more social than previously thought. Through the aide of camera traps in the Greater Yellowstone Ecosystem, biologists captured video evidence of female mountain lions sharing food at a variety of kill sites. The videos represent some of the first evidence of social interaction and cooperation between these large, evasive predators. More opportunities are just waiting for the next generation of research biologists to discover the true and complete story of the lifestyle of the mountain lions of the Americas.

A new undersea video is going viral for all the right reasons. Specifically: fish-on-fish-on-snail action, as well as a shocking twist.

The video, released by the National Oceanic and Atmospheric Administration's (NOAA) Ocean Exploration and Research Program, opens on a scene somewhere off the coast of the Southeastern United States, where an an Atlantic midshipman fish (Porichthys plectrodon) lays in wait, buried face-up in a shallow hole. Arrayed around its grim, ugly face are the local invertebrate bottom-dwellers, a sea snail and several quill worms. They all inch toward the precipice as if they're curious, apparently oblivious to the danger.

"It's a race to the burrow," an unseen NOAA researcher says over the video's spooky music. "The snail is winning."

The researcher seems unaware of what's going to come next, and indeed it looks as if the snail might march carelessly right into the not-very-well-hidden trap.

But then...

...a shock of blue enters from the left of the frame, as if hurtling deliberately into the hole. It's a barracudina in the family Paralepididae, according to a NOAA statement. A substance like dark, liquid smoke rises from the hole to fill the frame as predator and prey briefly struggle. When it clears, neither are visible. Only the snail remains, still perched on the very edge of the hole while the quill worms look on.

In one final moment of strange undersea grace, the snail leans too far past the edge of the burrow and plunges in as well.

The video was collected as part of NOAA's 2018 Windows to the Deep expedition, a series of robotic dives from the ship Okeanos Explorer to explore the region off the eastern coast of Florida, Georgia, and the Carolinas.

Editor's note: This story was updated at 10:15 am Eastern, July 20 to correct the name of the fish captured. It was a barracudina, not a barracuda.

Originally published on Live Science.

American alligators are beautiful, amazing, horrible monsters. As such, there are many parts of their body that they can obviously hurt you with. Up front, they've got wide, grinning toothy mouths that can clamp down on your limbs with deadly force. In the back, they've got powerful tails for thwacking. Even alligator claws are wicked, though they don't usually use them to fight.

But, as one trapper in Ocoee, Florida experienced firsthand yesterday (June 6), even an alligator with nearly all those parts pinned down has a weapon of last resort: the incredible thwack of its hard skull. [Alligators vs. Crocodiles: Photos Reveal Who's Who ]

A local NBC affiliate shared a video on Twitter that begins with an alligator trussed up on a sidewalk in a residential neighborhood, surrounded by a trapper and several police officers. Its jaws are taped shut, its eyes blindfolded, its four limbs are tied behind its back, and its tail lolls harmlessly behind its body. The trapper bops the alligator on the head several times. (Exactly what his goal is is unclear, though alligator trappers do often rub the creatures' bodies to calm them down.)

Eventually, the trapper and the officers grip the alligator and lift it toward the back of a pickup truck. Just as its tail contacts the truckbed, the alligator snaps its head back, apparently head-butting the trapper. The incredible force of the blow sends his sunglasses shooting off of his head, and he falls over, reportedly unconscious. One of the police officers topples as well, struck by the writhing tail. The alligator slithers off the back of the truck, and plops back onto the ground.

John Hutchinson, an expert in animal motion at the University of London, said that no one's ever studied just how much speed and power an alligator can deliver with a head butt, but that it doesn't surprise him to learn it's enough to knock a man out.

"Gators have large neck muscles for handling prey, and those muscles have fast-twitch fibers so they can contract quickly," Hutchinson told Live Science.

He added that he wouldn't be comfortable judging the trapper for the alligator's treatment or for the end result.

"It’s a tough situation because the gator was in a populated area and needed to be removed, hopefully to somewhere safer. Someone could have been more seriously hurt. The gator was blindfolded which calms them, and the trussing shown would be uncomfortable but not causing permanent injury," Hutchinson said.

"The trapper and police were putting themselves in harm’s way, and they didn't kill the gator outright, so one might say that they were making the best of a bad situation," he said.

Originally published on Live Science.

A tiny but proficient jumper named Kim is the first spider ever trained by scientists to leap on demand.

Teaching her to jump when and where they wanted her to wasn't easy. Of the four spiders the researchers tried to train, only one — which they eventually nicknamed Kim — would obligingly hop between parallel platforms and leap to higher or lower levels. By studying Kim, the scientists hoped to better understand how jumping spiders fine-tuned their jumps, depending on the purpose of the leap, the distance of their target and the jump's direction — upward or downward. [Creepy, Crawly & Incredible: Photos of Spiders

After observing and measuring Kim's performance, the scientists described their findings in the most detailed study of spider jumps to date, published online May 8 in the journal Nature: Scientific Reports.

The regal jumping spider (Phidippus regius), which measures only 0.5 inches (12 millimeters) long, is part of a group that is well-known for using swift, long-distance jumps to catch fast-moving insect prey or navigate tricky terrain and avoid threats. And while most jumping spiders measure between 0.1 and 0.4 inches (3 to 10 mm), they are capable of leaping horizontally up to 6 inches (160 mm) from a standstill.

"The force on the legs at take-off can be up to five times the weight of the spider. This is amazing," lead study author Mostafa Nabawy, a researcher at The University of Manchester's School of Mechanical, Aerospace and Civil Engineering, said in the statement.

"If we can understand these biomechanics, we can apply them to other areas of research," Nabawy said.

Might as well jump

Previous studies examined spiders' jump speed and body position, but much about their jumping was still unknown, such as how they adjusted their posture to compensate for different conditions, the amount of energy that powered their jumps and how much their jumps relied on muscular force, rather than hydraulic pressure that sends blood rushing to their legs, the study authors reported.

To investigate the spiders, they built a structure with two movable platforms that could be fixed at different levels and distances, and then tried to train four female P. regius spiders to jump between the platforms, by carrying them back and forth to familiarize them with the apparatus.

Most of the spiders showed no interest in the experiment. Kim, however, jumped at the opportunity, becoming the scientists' lone source of data. She performed in 15 jumping tasks, leaping up, down and across the platforms, while the researchers filmed her with high-speed cameras. They recorded her speed, landing positions, leg and body angles, and lengths of the jumps, and then calculated how much energy Kim spent on every leap.

They also scanned and modeled Kim in 3D, to better visualize the structures and movements of her legs and body.

The researchers found that Kim deployed different strategies depending on where she had to jump. She adjusted the position of her legs depending on the distance of the targets, and she used lower-angled jumps to travel shorter distances, and steeper jumps for longer distances.

The short-range horizontal jumps tended to be lower and faster, requiring Kim to expend more energy but minimizing the amount of time she was in the air — and likely increasing her chances of catching prey. By comparison, long-distance horizontal hops or jumps to a higher or lower platform required her to use less energy, according to the study.

Spiders' leg movements are known to employ both muscles and hydraulic pressure — mechanisms in their bodies send blood swiftly flowing to their limbs when they extend their legs. But the scientists noted that there was enough force generated by Kim's leg muscles alone to fuel her leaps, without requiring her to rely on hydraulic pressure to propel swift takeoffs.

However, further research would be necessary to confirm whether the spiders do, in fact, push off solely with muscular power, the scientists reported.

Original article on Live Science.

This ancient, gummy whale is breaking all the rules.

The weird marine beast, called Llanocetus denticrenatus, lived about 34 million years ago. It was big. It was an early ancestor of modern humpbacks and blue whales. And (this is the maverick, rule-breaking bit for a whale of its type) it had thick gums studded with teeth.

Today, all the biggest whales are filter feeders, while only small whales of the odontocetl group (including belugas, sperm whales, and all dolphins and porpoises) still chew their food.

Modern large whales instead suck huge volumes of water through stringy bristles in their mouth called baleen, separating out tons of tiny organisms, which they digest en masse. This is such an essential feature of the group of massive whales, or Mysticetes, to which L. denticrenatus also belongs, that biologists call whales in this group baleen whales. [Whale Album: Giants of the Deep]

But L. denticrenatus, according to a paper published today (May 10) in the journal Current Biology, didn't have any baleen.

After the flesh of ancient creatures has long rotted away, it can be tricky to determine what these animals looked like when they were alive. But researchers studied a remarkably complete L. denticrenatus skull found in Antarctica and were able to make some judgments about the flesh it likely supported, based on its ridges, grooves, and holes for blood vessels and nerves.

L. denticrenatus, they found, did have large gums, which included some signs of features that may have preceded baleen. But those gums were studded with teeth — the sort of teeth creatures use to take bites out of one another.

That's bizarre, because L. denticrenatus was also huge, growing to be up to 26 feet (8 meters) long, according to researchers. And, as Live Science previously reported, researchers have long believed that only filter-feeding whales could grow larger than about 20 feet (6 m).

"The giants of our modern ocean may be gentle, but their ancestors were anything but," study author Felix Marx, a paleontologist at the Royal Belgian Institute of Natural Sciences, said in a statement. "Llanocetus was both large and a ferocious predator and probably had little in common with how modern whales behave."

This finding also reverses the order researchers had long assumed for whale evolution. L. denticrenatus may have been what researchers call a "suction-assisted raptorial feeder" — a big animal that sucks smaller animals into its mouth before noshing on them — but it didn't do any filter feeding.

"Until recently, it was thought that filter feeding first emerged when whales still had teeth," researcher R. Ewan Fordyce, a paleobiologist at the University of Otago in New Zealand, said in the same statement. "Llanocetus shows that this was not the case."

Originally published on Live Science.

David Steen received his Ph.D. in Biological Sciences from Auburn University and is now a Research Ecologist at the Georgia Sea Turtle Center on Jekyll Island. Steen has published dozens of scientific papers about wildlife ecology and conservation biology and is also an award-winning science communicator known for his wide-ranging outreach efforts (find him on Twitter, Instagram and Facebook. Finally, Steen is Executive Director of The Alongside Wildlife Foundation, a nonprofit he founded to promote science-based solutions to living alongside wildlife in perpetuity. Steen contributed this article to Live Science's Expert Voices: Op-Ed & Insights.

Species are rapidly disappearing all around us; indeed, you and I are living through Earth's sixth great extinction. Most reasonable people agree that losing species is a problem. However, as a conservation biologist and a science communicator, I am used to hearing the occasional argument from radicals about why we need not be especially concerned about that loss. Imagine my horror to see these arguments compiled into a Perspectives piece published in The Washington Post, and written by a professor of biology no less! I cannot believe that it is 2018 and I have to explain why extinction is actually a bad thing, but here we are.

The piece works hard to make the case that we need not be particularly distressed about the loss of biodiversity by arguing, if you will humor me some loose paraphrasing, that we are going to lose species no matter what and extinction does not make much of a difference anyway because new species might evolve in the future. But for this line of reasoning to make sense one must ignore decades of conservation science and centuries of art, literature and philosophy, not to mention millions of years of evolution. Although there have already been many responses to the article — nearly unanimous in their disapproval — I feel compelled to go on record as well and explain why the article was so aggravating to me, as someone who puts a lot of time and effort into helping people appreciate and value biodiversity.

Mainly, the author should have known better.

As an accomplished evolutionary biologist, the author must recognize how silly it is to describe the gradual change of evolutionary lineages over millions of years, and argue this process is synonymous — biologically and ethically — to our ongoing and rapid extinction crisis. Today, our actions are actually ending lineages, and in only a few scant years too, while simultaneously destroying the evolutionary stage, the animals' habitats.

One of the foundations of a graduate education is learning how to appreciate and understand a subject before critically evaluating it. A few moments spent talking to any conservation biologist would have revealed to the author why so many scientists and environmentalists are concerned about the issues he callously tosses aside.

For example, the author questions why invasive species — animals that are not native to a habitat — are perceived as negative, despite the fact that they often increase the number of species in a given area. There is a pretty simple answer. Conservation biologists do not view conservation as a game, in which the goal is to create areas with the highest species counts. Rather, our priorities are based on the preservation of native ecosystems and their communities of unique species.

Although the article frames conservation as a field attempting to save species in isolation, it has been nearly 70 years since the philosopher and scientist Aldo Leopold emphasized the importance and complexity of ecological interactions in natural communities, and how these communities begin to fall apart when their member species are lost. He noted that keeping "every cog and wheel is the first precaution of intelligent tinkering." Consequently, he would not likely subscribe to the worldview espoused in the Washington Post article, nor would the generations of scientists that came after him.

Finally, when the author argues that extinctions will not significantly change our way of life, to whom is he referring? Who is part of the "developed society" that the author sees in our shared future? Does "we" include all of the world's different cultures and their unique relationships with nature, or is he actually just envisioning a future world like his own?

I could go on. The piece is littered with mischaracterizations and oversights all seemingly in service to nihilistic proclamations about biodiversity loss; the article is not a robust scholarly work so I will not treat it as such. It is a shame that the article did not reflect much familiarity with the work of scientists and philosophers who have built their careers studying and communicating conservation issues.

After the article's publication and in the face of mounting criticism, the author seemed to backtrack considerably from the points he made in the article while responding to critics on the Facebook page I use for science outreach and in a longer piece that he posted on his own Facebook page. Specifically, he claimed that he values conservation efforts but was not able to effectively communicate this in the article because of, among other things, restrictive word limits. Frankly, I feel that this explanation rings hollow, given he used 247 words to make the case in one paragraph of the original article that biodiversity — both the pinnacle and foundation of life on Earth — can actually be bad.

Why do I care so much about a single article? I care because I worry that it provides the public with a distorted view of how biologists view our ongoing extinction crisis while also providing ammunition to those who wish to unsustainably exploit our natural resources.

But perhaps I fear most of all that the piece will demoralize those who care about conservation and biodiversity.

In truth, we are surrounded by conservation successes; we have brought iconic species like the American alligator and the bald eagle back from the brink of extinction because we recognized their value and we fought for them. We can and will do it again for other imperiled species. For me, extinctions caused by our actions will never be spiritually or culturally acceptable.

And I know I am not alone.

Original article on Live Science.

A type of brightly colored sea slug has a taste for microscopic marine creatures called zooplankton, and it feeds on them using a method that's never been seen before: It captures quantities in a gulp by using a middleman.

The sea slug's unsuspecting helpers are hydroid polyps — tiny, coral-like animals that live in colonies and gorge on zooplankton. And the sea slug, known as a nudibranch, treats the polyps as living fishing nets, avidly scooping them up and swallowing them down as soon as the hapless hydroids finish their zooplankton supper.

Some animals, such as hyenas, are known for a behavior called kleptoparasitism, in which they wait until an animal kills its prey and then drive the predator away to claim its meal. However, this nudibranch behavior — stealing the predator's feast by swallowing the predator and prey together — is something that was previously unknown, and researchers dubbed it "kleptopredation" in a new study. [Gallery: Jaw-Dropping Images of Life Under the Sea]

The nudibranch Cratena peregrina is a common type of bottom-dwelling marine mollusk found in the Mediterranean and the Atlantic coastal waters near the Iberian Peninsula, Senegal and the Canary Islands. It measures about 1 to 2 inches (3 to 5 centimeters) in length, and has a pale body covered with colorful, elongated, fleshy spines called cerata, which help with respiration by increasing the surface area on the upper part of the animal's body.

C. peregrina was previously known to feed on hydroid polyps, but the study authors discovered that the nudibranchs preferred polyps that had just eaten. In experiments, when presented with a colony of polyps that had just fed and a colony that was "empty," the sea slugs ate twice as many of the polyps that were full of zooplankton.

In fact, kleptopredation provides the nudibranchs with enough plankton to account for about half of their diet, overturning previous claims that polyps were the nudibranchs' primary food source, according to the study.

Their findings hint that nudibranchs may not be the only marine creatures to use this previously unknown strategy, and that predator-prey interactions in this group may be more complex than once thought, the researchers wrote. 

"This may be widespread among other invertebrate specialists, altering our understanding of the functional roles of suspension feeders," the study authors reported online today (Nov. 1) in the journal Biology Letters.

Original article on Live Science.