Surfer, spear-fisher and free-diver Riley Elliott and marine biologist, shark diver and underwater photographer Kori Burkhardt put themselves in harm's way in don't-try-this-at-home "Shark Week" 2026 special "Secrets of the Great White Kill", and Live Science is here with all the TV and streaming details.

It doesn't always go to plan, as this seal uprising and vengeful turtle demonstrate, but great white sharks (Carcharodon carcharias) are known for attacking prey from below with such frightening speed and power it can propel their enormous bodies clear out of the water and stun or even kill their prey upon impact.

However, closer inspection has revealed that they can be a little more subtle when the need arises

In "Secrets of the Great White Kill," Eliott and Burkhardt aim to capture and unpack the full range of great white hunting techniques, including one or two surprising methods, the nuances of which have never been fully appreciated before.

How to watch "Secrets of the Great White Kill" in the U.S.

"Secrets of the Great White Kill" airs on Discovery at 8 p.m. ET/PT on Friday, July 31.

If you don't have the Discovery channel on cable, it's available on a streaming basis from several cable alternatives. Best of all, many of the services offer a free trial to new customers.

YouTube TV usually costs $82.99 per month but comes with a free trial and $15 off each of your first five months.

The DirecTV MyEntertainment genre pack costs $42.99 per month after a 5-day free trial, and Hulu + Live TV costs $89.99 per month after a 3-day free trial.

Alternatively, the HBO Max streaming service starts at $10.99 per month.

Can you watch "Secrets of the Great White Kill" in the U.K.?

"Shark Week" programming typically airs on Discovery+ in the U.K. at a later date.

At the time of publication, plans for "Secrets of the Great White Kill" and the other 2026 specials are still firmly under wraps.

If you're currently in the U.K. for work or on vacation from the U.S., you can still catch "Secrets of the Great White Kill" by using a VPN, such as Surfshark.

Watch "Secrets of the Great White Kill" from anywhere

If you're travelling abroad you can access your usual streaming services from anywhere with a good VPN.

A VPN, or virtual private network, is a piece of internet security software that can alter your device's digital location, unlocking the geo-restrictions on most streaming platforms.

Our expert colleagues at TechRadar rate Surfshark as one of the best VPNs. Not only is it great for unblocking streaming services, it has top-level security features, a reasonable price tag and, right now, a big discount.

We test and review VPN services in the context of legal recreational uses. For example: 1. Accessing a service from another country (subject to the terms and conditions of that service). 2. Protecting your online security and strengthening your online privacy when abroad. We do not support or condone the illegal or malicious use of VPN services. Consuming pirated content that is paid-for is neither endorsed nor approved by Future Publishing.

Whale sharks may be the biggest fish in the ocean, but their feeding habits have remained mysterious. Now, new camera footage from the backs of these gentle giants has captured them doing something scientists rarely get to see: hunting for food far below the surface.

The footage reveals that whale sharks (Rhincodon typus) spend far more time feeding underwater than scientists realized and that they use a surprising variety of foraging techniques that had never been documented before.

The videos show whale sharks filtering food while cruising through open water, gliding downward as they feed during dives, climbing back toward the surface with their mouths still open, and cruising just above the seafloor to feed. Slow, steady underwater feeding turned out to be one of the sharks' most common activities.

Philip Motta, a professor emeritus of biology at the University of South Florida who was not involved in the study, said the videos provide "very valuable" new information on the variability of whale shark feeding behaviors, which have been poorly documented to date.

Cameras reveal whale shark feeding

Before this study, whale sharks had been studied from boats, from planes and by divers swimming alongside them. But those methods shared a blind spot: They could only follow the sharks when they were near the surface.

Earlier research had hinted that whale sharks spend a lot of time feeding out of view, at varying depths. In a 2020 study, researchers estimated that whale sharks may forage at these depths for up to 20% of the day and feed at the surface for less than 1% of their time.

In the new study, scientists strapped cameras directly onto the whale sharks, offering a rare shark's-eye view beneath the waves.

They deployed camera tags on 10 whale sharks at Ningaloo Reef in Western Australia and gathered more than 22 hours of footage from the sharks' own perspective. They combined that footage with a review of 106 previously published studies to build the most comprehensive catalog of whale shark behavior to date. Ultimately, they cataloged 36 distinct behaviors ‪—‬ 12 were related to feeding, and of those, six had never been recorded before. The findings were published July 21 in the journal Marine Biology.

Whale sharks can grow to 60 feet (18 meters) in length. And yet, this enormous fish survives on tiny prey ‪—‬ like krill, fish eggs and plankton ‪—‬ in tropical waters that are notoriously poor in nutrients. The ability to switch between so many feeding techniques may help to explain the long-standing puzzle of how such a large species can survive in these nutrient-poor waters.

However, even with a shark's-eye view, the cameras captured only part of the story. Whale sharks are known to dive hundreds of feet below the surface, where sunlight disappears and conventional cameras can no longer record.

"The most important new discoveries could be what these gentle giants are doing when they perform really deep dives," Motta said.

Shark quiz: How much do you know about these iconic ocean superstars?

"Expedition X: Atomic Sharks" – a "Shark Week" 2026 special – sees biologist Phil Torres and "Expedition X" host Heather Amaro explore the islands' waters, including Troy's Coral Head, to establish if nuclear fallout could be behind reports of sharks displaying unusual and highly aggressive behaviors.

The U.S. military detonated 67 nuclear bombs at Bikini Atoll and Enewetak Atoll over 12 years from 1946 to 1958, which inflicted catastrophic and irreversible harm on the local populace and environment. Cancer rates among residents increased significantly, and local produce was rendered unfit for consumption.

Half a century later, however, the Marshall Islands became the site of the world's largest shark sanctuary.

How to watch "Expedition X: Atomic Sharks" in the U.S.

"Expedition X: Atomic Sharks" airs on Discovery at 8 p.m. ET/PT on Wednesday, July 29.

If you don't have the Discovery channel on cable, it's available on a streaming basis from several cable alternatives. Best of all, many of the services offer a free trial to new customers.

YouTube TV usually costs $82.99 per month but comes with a free trial and $15 off each of your first five months.

The DirecTV MyEntertainment genre pack costs $42.99 per month after a 5-day free trial, and Hulu + Live TV costs $89.99 per month after a 3-day free trial.

Alternatively, the HBO Max streaming service starts at $10.99 per month.

Can you watch "Expedition X: Atomic Sharks" in the U.K.?

"Shark Week" programming typically airs on Discovery+ in the U.K. at a later date.

At the time of publication, plans for "Expedition X: Atomic Sharks" and the other 2026 specials are still firmly under wraps.

If you're currently in the U.K. for work or on vacation from the U.S., you can still catch "Expedition X: Atomic Sharks" by using a VPN, such as Surfshark.

Watch "Expedition X: Atomic Sharks" from anywhere

If you're traveling abroad you can access your usual streaming services from anywhere with a good VPN.

A VPN, or virtual private network, is a piece of internet security software that can alter your device's digital location, unlocking the geo-restrictions on most streaming platforms.

Our expert colleagues at TechRadar rate Surfshark as one of the best VPNs. Not only is it great for unblocking streaming services, it has top-level security features, a reasonable price tag and, right now, a big discount.

We test and review VPN services in the context of legal recreational uses. For example: 1. Accessing a service from another country (subject to the terms and conditions of that service). 2. Protecting your online security and strengthening your online privacy when abroad. We do not support or condone the illegal or malicious use of VPN services. Consuming pirated content that is paid-for is neither endorsed nor approved by Future Publishing.

"Demon cavefish" have been discovered lurking in caverns beneath a contaminated U.S. Army base in Alabama, a new study has found.

Biologists have named the pale, eyeless creatures Demogorgonichthys arcanus, after the monstrous Demogorgons from Netflix's "Stranger Things" and the underworld demon of Greek mythology from which the Demogorgon name derives. They are likely among the rarest fishes in the world.

The find came as a shock to scientists because the cavefish's home, Bobcat Cave, has been extensively studied in recent decades. The subterranean system is part of U.S. Army site Redstone Arsenal, which was historically a center for chemical weapons production. Bobcat Cave is regularly subject to water quality monitoring and part of efforts to save endangered Alabama Cave Shrimp (Palaemonias alabamae), which also call the cave home.

In a new study, published July 6 in the journal Scientific Reports, researchers described the cavefish find as a "discovery in plain sight." Study lead author Matthew Niemiller, who directs the cave biology lab at The University of Alabama in Huntsville, encountered the cavefish by chance during a routine survey of Bobcat Cave's largest chamber, known as the Shrimp Room, in early 2025.

"I slipped in the mud at the back of the Shrimp Room and fell into a deeper pool," Niemiller told Live Science in an email. "During my graceful plummet, I disturbed a cavefish and crayfish underneath a rock ledge."

Niemiller quickly snapped photos of the animals using an underwater camera before silt clouded his view of them. It wasn't until several days later, when he checked the photos, that he noticed the cavefish looked different from southern cavefish (Typhlichthys subterraneus), a known species within the cave.

"The new cavefish had a pronounced hump behind the head, a longer, flatter snout, and unbranched fin rays," Niemiller said. "We returned a few days later, before a storm system forecasted to dump several inches of rain moved into the area. On the next trip, we confirmed that nearly half of the cavefish we observed were this new species."

Niemiller studied the cavefish with colleagues at Auburn University, The University of Alabama and Mississippi State University, with students performing much of the lab work. Genetic analysis revealed that demon cavefish didn't fit within any known cavefish group. Notably, demon cavefish carry unique disabling mutations for rhodopsin, a light-sensitive protein that would otherwise support dim light vision. Niemiller noted that this mattered for two reasons.

"First, it's a great example of 'use it or lose it' at the molecular level," he said. "In total darkness, vision is useless, so natural selection stops maintaining the gene, and mutations simply accumulate. Second, and more importantly, the specific way this fish's rhodopsin is broken is different from how it's broken in the related cavefish it lives alongside. That's strong evidence they lost their vision independently."

Demon cavefish and southern cavefish seemingly losing the ability to see independently is an example of how evolution can lead different species to converge on the same physical characteristics when they're suitable for an environment.

The conditions in Bobcat Cave have likely been influenced by the history of the military base above it. Redstone Arsenal made various chemical weapons during World War II. At the end of the war, vast quantities of chemical munitions were buried at the site, along with chemical weapons from overseas, like British mustard gas and nerve agents and other toxic weapons recovered from Nazi Germany. The site is the subject of ongoing investigations, clean-ups and storage.

Researchers have found that the cave contains elevated levels of trace metals compared to what would normally be found in such a habitat. However, Niemiller noted that the restricted-access status of the military installation does limit disturbance in the cave.

A bigger concern for the demon cavefish is that surface water connects to the cave's groundwater, so the life in the cave is also exposed to runoff, sediment and contaminants linked to the nearby city of Huntsville. As demon cavefish are, as far as we know, restricted to a single cave, they are very vulnerable to extinction.

The researchers concluded that demon cavefish would meet the criteria for becoming a "critically endangered" species, under the International Union for Conservation of Nature (IUCN) Red List — a framework for determining a species' conservation status. It's unknown how many demon cavefish live within the cave, and it's likely that many of them will be in places that are inaccessible to researchers.

"Like other cavefish, these animals probably spend much of their lives down in the water-filled aquifer below the cave, beyond where we can observe them, so any single survey is a snapshot, not a census," Niemiller said. "What we can say with some confidence is that it's known from just one cave system, it's rarely encountered, and by every measure we use, it qualifies as critically imperiled."

Fortunately for the cavefish, Bobcat Cave is already known for being a home for endangered Alabama Cave Shrimp. Since 1990, the cave has been a focus for water quality monitoring, shrimp surveys, and other biological investigations that should also help the newfound species.

"What protects the shrimp's water protects the fish's water too," Niemiller said.

We've all heard of the fearsome megalodon, the largest known shark to have ever lived, but how about its predecessors, contemporaries and successors? Shark Week premiere "Jurassic Sharks" uses CGI to flesh out the fossils of ancient cartilaginous fish, and Live Science is here with all the TV and streaming details.

Using fossil records and "cutting-edge" visual effects, "Jurassic Sharks" will attempt to trace the ancestry of modern-day species back through millions of years, and build a picture of the prehistoric ocean, complete with superpredators that are both weird and awe-inspiring.

It's a must-watch for budding palaeontologists and animal fans alike.

How to watch "Jurassic Sharks" in the U.S.

"Jurassic Sharks" airs on Discovery at 8 p.m. ET/PT on Tuesday, July 28.

If you don't have the Discovery channel on cable, it's available on a streaming basis from several cable alternatives. Best of all, many of the services offer a free trial to new customers.

YouTube TV usually costs $82.99 per month but comes with a free trial and $15 off each of your first five months.

The DirecTV MyEntertainment genre pack costs $42.99 per month after a 5-day free trial, and Hulu + Live TV costs $89.99 per month after a 3-day free trial.

Alternatively, the HBO Max streaming service starts at $10.99 per month.

Can you watch "Jurassic Sharks" in the U.K.?

"Shark Week" programming typically airs on Discovery+ in the U.K. at a later date.

At the time of publication, plans for "Jurassic Sharks" and the other 2026 "Shark Week" specials are still firmly under wraps.

If you're currently in the U.K. for work or on vacation from the U.S., you can still catch "Jurassic Sharks" by using a VPN, such as Surfshark.

Watch "Jurassic Sharks" from anywhere

If you're traveling abroad you can access your usual streaming services from anywhere with a good VPN.

A VPN, or virtual private network, is a piece of internet security software that can alter your device's digital location, unlocking the geo-restrictions on most streaming platforms.

Our expert colleagues at TechRadar rate Surfshark as one of the best VPNs. Not only is it great for unblocking streaming services, it has top-level security features, a reasonable price tag and, right now, a big discount.

We test and review VPN services in the context of legal recreational uses. For example: 1. Accessing a service from another country (subject to the terms and conditions of that service). 2. Protecting your online security and strengthening your online privacy when abroad. We do not support or condone the illegal or malicious use of VPN services. Consuming pirated content that is paid-for is neither endorsed nor approved by Future Publishing.

Great white sharks can launch themselves clear out of the ocean, but why they breach so dramatically remains one of marine biology's biggest mysteries. "Air Jaws: Red, White and Breach", premiering during "Shark Week" 2026, follows a team of filmmakers and scientists as they investigate the shark's behavior.

"Shark Week" is now in its 25th year, and to mark this milestone, Jeff Kurr and marine biologist Alison Towner head to the Californian coast, which has seen an unexpected surge of great whites (Carcharodon carcharias) breaching the surface.

With cinematographer Andy Casagrande in tow, "Air Jaws: Red, White and Breach" aims to capture this behavior in full glory, and to establish why breaching great whites have entered American waters.

How to watch "Air Jaws: Red, White and Breach" in the U.S.

"Air Jaws: Red, White and Breach" airs on Discovery at 9 p.m. ET/PT on Sunday, July 26.

If you don't have the Discovery channel on cable, it's available on a streaming basis from several cable alternatives. Best of all, many of the services offer a free trial to new customers.

YouTube TV usually costs $82.99 per month but comes with a free trial and $15 off each of your first five months.

The DirecTV MyEntertainment genre pack costs $42.99 per month after a 5-day free trial, and Hulu + Live TV costs $89.99 per month after a 3-day free trial.

Alternatively, the HBO Max streaming service starts at $10.99 per month.

Can you watch "Air Jaws: Red, White and Breach" in the U.K.?

"Shark Week" programming typically airs on Discovery+ in the U.K. at a later date.

At the time of publication, plans for "Air Jaws: Red, White and Breach" and the other 2026 specials are still firmly under wraps.

If you're currently in the U.K. for work or on vacation from the U.S., you can still catch "Air Jaws: Red, White and Breach" by using a VPN, such as Surfshark.

Watch "Air Jaws: Red, White and Breach" from anywhere

If you're traveling abroad you can access your usual streaming services from anywhere with a good VPN.

A VPN, or virtual private network, is a piece of internet security software that can alter your device's digital location, unlocking the geo-restrictions on most streaming platforms.

Our expert colleagues at TechRadar rate Surfshark as one of the best VPNs. Not only is it great for unblocking streaming services, it has top-level security features, a reasonable price tag and, right now, a big discount.

We test and review VPN services in the context of legal recreational uses. For example: 1. Accessing a service from another country (subject to the terms and conditions of that service). 2. Protecting your online security and strengthening your online privacy when abroad. We do not support or condone the illegal or malicious use of VPN services. Consuming pirated content that is paid-for is neither endorsed nor approved by Future Publishing.

Researchers have identified a new species of "walking shark," a rare group of small carpet sharks that use their fins to "walk" along shallow reefs.

A team of divers spotted the newfound shark, which they named Hemiscyllium dudgeonae, in the dark waters around the reefs of southeastern Papua New Guinea. Gliding along the rocks was a small, brown-spotted shark that they didn't recognize.

"I was so excited. … I didn't look very closely at the pattern and quickly caught it and took it back to the boat," Christine Dudgeon, a senior research fellow at the University of the Sunshine Coast in Australia, told Live Science in an email.

Dudgeon handed the shark to Jess Blakeway, a doctoral student and first author of a new study describing the shark. Blakeway "noticed that the shark had a different pattern to the one that we were looking for and called out to me: 'Chris, it's different.'"

The new shark is named the Dudgeon's walking shark after Dudgeon, in recognition of her 20 years of researching the Hemiscyllium genus.

The new find, described June 15 in the Journal of the Ocean Science Foundation, brings the number of known walking shark species to 10, each with their own unique body pattern.

"This discovery is exciting because a lot of new fishes, and in particular, new shark and ray species, tend to be deep sea, so finding something in very shallow [less than 3 feet, or 1 meter] of water is unusual and highlights that there is potentially a lot of biodiversity that we really don't know about," Dudgeon said.

Encountering a new species

The team had been searching for another walking shark species, called Michael's walking shark (Hemiscyllium michaeli), when they encountered the unusual shark.

"Michael's walking shark has leopard prints and Dudgeon's walking shark has small white dashes and brown dots all over its body," Dudgeon said. "But with only one specimen we were not sure if this was an anomaly or a true difference."

The researchers continued surveying nearby reefs, and within two days, they had located 11 additional Dudgeon's walking sharks across three sites. These included males and females, both juveniles and adults, with all displaying the distinctive body pattern. That consistency convinced the team that they were likely looking at an undescribed species.

Dudgeon and Blakeway used genetic data to test this hypothesis at their laboratory in Australia. By comparing DNA from the newly discovered sharks with genetic samples from the other nine walking shark species, they confirmed that the population represented a new species.

Walking on land

Walking sharks are notable for their unusual biology. Unlike larger, open-ocean shark species, walking sharks spend their lives near coral reefs. Their ability to "walk" across the seafloor using their pectoral and pelvic fins is particularly useful during low tide, when parts of the reef become isolated from deeper waters. "Walking" helps the animals remain active when oxygen levels drop so that they can continue hunting prey across reef flats.

Scientists think this ability evolved as a response to the challenging environment of tropical reef flats, where oxygen levels can shift dramatically as the tides rise and fall.

Studies indicate that some walking sharks can survive in low oxygen environments for hours, though more research is needed to understand how the sharks are able to do this, Dudgeon said.

So far, Dudgeon's walking shark has been documented at only three locations in Papua New Guinea. If future research confirms that the species has a highly restricted range, H. dudgeonae could be vulnerable to habitat degradation, climate change or overfishing.

Many walking shark species appear to stay close to the reefs where they were born, which limits their ability to recolonize damaged habitats. Species with small geographic ranges are often more susceptible to population declines because local disturbances can affect a larger portion of the total local population.

The discovery also shows how new shark species are still being found in regions that have received relatively little scientific attention. Dudgeon and her team plan to continue doing surveys in Papua New Guinea to study the new species in its home environment.

"I think many people are not aware of the wonderful diversity of sharks and their relatives, the rays, skates and chimeras," Dudgeon said. "Very few species are dangerous to humans and they are a wonderfully broad and eclectic group of animals. They continue to surprise and fascinate us."

How much of a shark fan are you? Find out with our shark quiz!

For the first time ever, scientists have captured deep-sea footage of the elusive goblin shark, extending its known range far into the Central Pacific and down to nearly 6,560 feet (2,000 meters) below the water's surface.

The goblin shark (Mitsukurina owstoni) is a deepwater shark with an elongated snout and protrusible jaws that shoot out to snatch prey. The species, which has been around for about 125 million years, is described as a "living fossil." Until now, it had been seen alive only briefly, when it got hooked on fishing lines and hauled to the surface, according to a new study.

In the new footage, researchers documented two goblin shark sightings — one near Jarvis Island in the South Central Pacific Ocean and another at the Tonga Trench in the Southwest Pacific. Researchers suspect that goblin sharks live throughout the planet's oceans, as they have been caught in many different regions, but the specimen record is very sparse. So far, goblin sharks have been found only in narrow regions in the Atlantic and Indian oceans, as well as in small patches off the western U.S., Australia, Japan and Taiwan.

"The goblin shark is a deep-sea charismatic animal, and I never thought we'd see one alive," study co-author Alan Jamieson, the director of the Minderoo-University of Western Australia Deep-Sea Research Centre, said in a statement.

Not only was it fascinating to capture footage of goblin sharks in their natural habitat for the first time, but the specimen in the Tonga Trench was found swimming 2,300 feet (700 m) deeper than any other goblin shark, at around 6,550 feet (1,997 m), Jamieson said.

"On that expedition we filmed over 50 days of continuous footage between depths of 800 and 10,800 metres [2,600 to 35,400 feet] and this observation was a little over 20 seconds long which is [a] testament to how elusive this species is, and how special it is to have two observations in the same study," he said.

The researchers made the Tonga Trench observation in August 2024, while the Jarvis Island record dates to July 2019. The Tonga Trench shark was likely female and swam along the trench's northern slope, the team wrote in the study.

The Jarvis Island shark, on the other hand, was a male that was more than 11 feet (3.4 m) long and probably over 51 years old. It swam above an unnamed seamount at a depth of 4,058 feet (1,237 m), according to the study, which was published May 19 in the Journal of Fish Biology.

"New discoveries like this demonstrate that there is still so much to explore in our deep ocean home," study first author Aaron Judah, a doctoral student in biological oceanography at the University of Hawaii at Manoa, said in the statement. "Given the newly expanded geographic range of the goblin shark, this species can be included in regional management and a nation's biodiversity list."

Shark quiz: How much do you know about these iconic ocean superstars?

The first-ever whole-genome sequence of a Greenland shark has revealed genetic clues to how the animals avoid cancer and live for hundreds of years. The work may pave the way to a better understanding of age-related diseases in humans.

Greenland sharks (Somniosus microcephalus) typically grow to about 13 to 16 feet (4 to 5 meters) and live long lives in the North Atlantic and Arctic oceans. Little is known about these sharks, partly because they live at depths of up to 1.65 miles (2.65 kilometers). They are estimated to live to about 400 years and don't reach maturity until they're about 150 years old, making them the longest-living vertebrates in the world.

Now, new research by Shigeharu Kinoshita, a fisheries chemist at the University of Tokyo, and his colleagues has uncovered nearly the entire sequence ‪—‬ 96.7% ‪—‬ of a Greenland shark genome. In their study, published May 19 in the journal PNAS, the researchers found a wealth of genes that could be linked to the sharks' longevity.

Key among the findings were genetic tweaks relating to unique amino acid substitutions in "linker histone proteins," a series of proteins that spool and compact DNA. These changes may stabilize the structure of the sharks' chromatin, the mixture of DNA and proteins that makes up the chromosomes. This, in turn, may help to suppress the accumulation of DNA damage over the sharks' exceptionally long lifespans, Kinoshita told Live Science by email.

The researchers also found that gene families related to immune responses and DNA repair pathways were expanded in the shark genome. This finding, Kinoshita said, supports the idea that efficient damage repair and regulation of the immune system are key components of both longevity and cancer resistance.

A third discovery that provides clues to the sharks' longevity was the marked expansion of ferritin genes, which are involved in iron storage and regulation. This gene expansion suggests the sharks have a boosted capacity to control iron metabolism and to limit oxidative stress, which can damage DNA and lead to cancer. It may also mean they restrict a mechanism called ferroptosis, an iron-dependent form of programmed cell death.

"Our genomic analyses revealed multiple lines of evidence pointing to enhanced genome stability and stress resistance in the Greenland shark," Kinoshita said. "Extreme longevity is likely governed not by a single gene, but by coordinated changes across multiple biological systems, including genome stability, iron metabolism, immune function, and stress resistance," he said, adding that the work could inform research on human aging and age-related diseases.

The features linked to immune enhancement, cancer resistance, DNA repair and chromatin stability may help to explain the shark's extreme lifespan, said Dorota Skowronska-Krawczyk, a physiologist and biophysicist at the University of California, Irvine, who recently showed how DNA-repair-associated genes in the retina may help keep the Greenland shark's eyesight clear over its long life. "This could be related to longevity and cancer resistance, but functional studies will be needed to test that idea directly," said Skowronska-Krawczyk, who was not involved in the research.

Previous work suggested that the sharks' metabolism remains stable throughout their lives, which has been given as another reason for their epic longevity.

Aaron MacNeil, a biologist at Dalhousie University in Nova Scotia who was not involved in the research, told Live Science that the results support the idea that the sharks are particularly long-lived. But MacNeil is skeptical of the 400-year age estimate, which is based on radiocarbon isotope traces left over from Cold War nuclear bomb testing seen in the eyes of sharks. The eye lenses grow in layers, so seeing where the isotope sits in the layers gives a fixed point in time that helps assess the animals' age.

The slow mixing of different layers of the ocean in the cold depths where Greenland sharks live means it could take longer for the bomb radiocarbon to reach the deep sea, and thus the age estimate for the sharks may be too high. "But we do know they're damn old — 200 years at least," MacNeil said.

How much of a shark fan are you? Find out with our shark quiz!

Hitchhiking fish that are famous for suctioning themselves to other marine animals have a very unexpected hiding place: the rear ends of manta rays, a new study finds.

These fish, known as remoras (family Echeneidae), frequently get free rides when they use their suction discs ‪—‬ modified backs, or dorsal fins ‪—‬ to latch onto marine animals like sharks, whales and sea turtles. It has generally been thought that remoras provide a cleaning service to the animal they are traveling with, picking parasites off their skin. But this new discovery shows that this relationship might not always be beneficial to the manta rays.

The suckerfish's behavior is "pretty weird," study first author Emily Yeager, a doctoral candidate in the Department of Marine Biology and Ecology at the University of Miami, told Live Science.

In one observation, a free diver swam near an adult Atlantic manta ray (Mobula yarae) and noticed a common remora (Remora remora) was near the ray's pelvic fins. The diver's presence seemed to startle the remora, which then "quickly inserted itself into the manta ray's cloacal opening," the researchers wrote in the study, which was published Monday (May 11) in the journal Ecology and Evolution.

The manta ray appeared bothered by the abrupt insertion. "In response to this intrusion, the manta ray briefly shuddered before continuing to swim away with the remora still inside of its cloacal opening," the team wrote.

The researchers were surprised to find remoras inside the cloaca, a hole that's a one-stop shop for copulating, having offspring and eliminating waste, Yeager said. The remora's cloacal proclivities reveal a previously undocumented behavior in one of the ocean's best known symbiotic relationships and may change how scientists view symbiotic relationships overall, Yeager said.

"Oftentimes they're just sort of seen swimming along with their hosts with no kind of visual negative consequence to their host," Yeager said.

But based on the images and videos of remoras sliding up manta ray behinds, Yeager thinks it may not be a harmless relationship. "The manta's ability to remove the remora is probably pretty non-existent," she said.

"My first reaction was a combination of amazement and horror — it's so cool that remoras can do that, but I imagine it's no fun for the manta," David Shiffman, an independent marine conservation biologist and author based in Washington, D.C. who was not involved with the study, told Live Science in an email.

For this study, Yeager collected data from manta ray scientists around the world and found cloacal diving recorded seven times in 15 years. These instances occurred in multiple oceans, spanning from the Maldives to Florida, in all three manta ray species (M. yarae, M. birostris and M. alfredi) and in both juveniles and adults. It's likely a widespread behavior but rarely seen, she said.

According to Yeager, one previous study hinted that very small remoras might have been in the cloacae of manta rays, and another study mentioned one remora in the cloaca of a whale shark. Sometimes, small remoras are spotted in the gill cavities of sailfish and rays.

Symbiosis or something else?

Yeager studies symbiosis — close, long-term interactions between two species living together — in the ocean. Historically, scientists have categorized these relationships into one of three types: mutualism, where both species benefit; commensalism, where one benefits without affecting the other; and parasitism, where one benefits at the other's expense. Remoras and their hosts have been thought of as either mutualism or commensalism, she said.

As far as remoras and manta rays, "I'd argue that this is evidence of more of a parasitic relationship, which is new to our kind of understanding of what these relationships are and how they function in the wild," she said.

For the manta rays, the suction may lead to physical injury or discomfort, increase their energetic costs as the manta rays try to remove the fish, and even interfere with reproduction, Yeagar said. She noted that mantas have been observed trying to dislodge remoras by leaping out of the water or scraping against the sand.

This reasoning contributes to Yeager's overall argument that symbiotic relationships shouldn't exist in discrete categories but rather a continuum, in which their partnership varies.

She compared it to relationships with your family. "You guys get along really well, but sometimes you're fighting, right?" she said. "And those types of relationships likely also exist in these ecological communities." It's just a matter of spending the time to observe them.

China's Yangtze River is showing signs of recovery following the introduction of a 10-year ban on commercial fishing in 2021. The number of large fish has increased, and there has been recovery among endangered animals, including the Yangtze sturgeon (Sinosturia dabryanus) and the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis), new research finds.

"These results show that strong political decisions are required to restore biodiversity," Sébastien Brosse, an ecologist at the University of Toulouse in France and co-author of the new study, told Live Science via email. "This is an encouraging message because biodiversity loss is often seen as irreversible." The Yangtze is the longest and largest river in China. About 30% of the country's population lives within its drainage basin, and the 11 provinces and municipalities that make up the Yangtze River Economic Belt generate about 47% of China's total gross domestic product.

But rapid urban development since the 1950s, dam building, decades of overfishing, pollution and habitat degradation had all led to a decline in water quality and a biodiversity crisis. The Yangtze River dolphin (Lipotes vexillifer) and the Chinese paddlefish (Psephurus gladius) went extinct, and 135 fish species found in historical surveys disappeared.

This decline continued despite the establishment of a network of protected areas and an investment of more than $300 billion in water-quality management and improvement. In response, China took drastic measures: The country instituted a 10-year fishing ban across the entire Yangtze basin in 2021, used river police to enforce strict penalties, and continued broad environmental management.

To assess the effects of the fishing ban, Yushun Chen, a hydrobiologist at the Chinese Academy of Sciences in Wuhan, China, and his colleagues used data from between 2018 and 2023 to evaluate the health of fish communities in the Yangtze before and after the ban went into effect.

They found that overall, the total mass of fish collected in samples more than doubled between those dates, and there was a 13% boost in the number of species in the samples.

The overall number of fish stayed about the same, but larger-bodied species that are higher up in the food web, including the economically valuable black Amur bream (Megalobrama terminalis) and the white Amur bream (Parabramis pekinensis), grew, and they contributed a larger amount of the biomass. However, the total mass of smaller species sampled decreased by 18%.

The team's findings, published on Thursday (Feb. 12) in the journal Science, also included positive signs for migratory and endangered species. For example, populations of slender tongue sole (Cynoglossus gracilis) increased after the ban, and its freshwater migration extended farther upstream. Endangered fish species — such as the Yangtze sturgeon, Chinese sucker (Myxocyprinus asiaticus) and tube fish (Ochetobius elongatus) — also showed signs of recovery.

Another notable positive was the boost in numbers of the only freshwater mammal remaining in the Yangtze River, the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis), whose population rose by a third from 445 in 2017 to 595 in 2022. This gain may have resulted from a greater availability of bigger fish to eat; fewer deaths related to vessel strikes or fishing bycatch; and a reduction in other stressors, such as underwater noise from vessel propellers, the researchers suggested.

"In an era of unprecedented biodiversity losses and declines, especially in freshwater systems, this study offers a glimpse of hope regarding the future of biodiversity," said Lise Comte, a conservation ecologist at California-based Conservation Science Partners who wasn't involved in the research.

"It demonstrates that bold protection and restoration strategies can be efficient in slowing down and even reverting human impacts on ecological communities," she told Live Science via email.

Chen and his colleagues are still monitoring Yangtze River biodiversity, and they said the recovery is continuing. But they warned that the progress could easily be reversed if commercial fishing were to restart and that lasting biodiversity recovery will depend on sustained management that addresses all human pressures on river systems.

They also suggested that similar conservation measures might be useful on rivers such as the Mekong and the Amazon.

However, the Yangtze fishing ban had huge human and financial costs, as it involved the recall of 111,000 fishing boats, the resettlement of 231,000 fishers, and an investment of more than $2.74 billion in the Yangtze River Economic Belt.

"The promising findings demonstrate the resilience of these systems but are also a case study of an approach that I hope we don't have to emulate elsewhere," co-author Steven Cooke, a professor of biology at Carleton University in Ottawa, Canada, told Live Science via email. "Closing all fisheries in a river basin has significant socio-economic consequences. Fishers, and those in related industries, often move on, forever changing those communities. Managing fisheries in ways that do not require such a 'nuclear' option is always preferred."

A better approach would involve the ongoing assessment of fish populations; science-based fisheries management; and the study of watersheds as integrated systems that connect people, water and fish, he added.

"Sharktober" — the spike in shark bite incidents off the west coast of North America during the fall — is real, and it seems to happen in Hawaii when tiger sharks give birth in the waters surrounding the islands, new research suggests.

Carl Meyer, a marine biologist at the University of Hawai'i at Manoa's Hawaii Institute of Marine Biology, analyzed 30 years' worth of Hawaii shark bite data, from1995 to 2024, and found that tiger sharks (Galeocerdo cuvier) accounted for 47% of the 165 unprovoked bites recorded in the area during that period. Of the others, 33% were by unidentified species and 16% were attributed to requiem sharks (Carcharhinus spp.)

About 20% of all the bites occurred in October, a frequency two to four times higher than in any other month, despite there being no evidence of more people being in the water for recreational activities at that time of year.

Crucially, tiger sharks accounted for at least 63% of the recorded bites during that month. What's more, 28% of the October bites involved unidentified species, some of which may have also been tiger sharks, Meyer wrote in the study, which was published Jan. 6 in the journal Frontiers in Marine Science."The October spike appears to be driven by tiger shark biology rather than changes in human ocean use," Meyer told Live Science via email.

Tiger sharks typically reach 10 to 14 feet (3 to 4.3 meters) long and weigh more than 850 pounds (385 kilograms). They are named for the dark vertical stripes that younger ones have, and they are found throughout the world in temperate and tropical waters, especially around central Pacific islands.

Tiger shark numbers are highest in the waters off Hawaii during October according to ecotourism operators. This month is also when large, mature females move from islands in the northwest Pacific to areas close to the shores around the main Hawaiian Islands to give birth. The increased presence of large sharks is one crucial factor that could lead to more bites, Meyer said.

"The most plausible explanation is seasonal reproduction: a partial migration of large adult female tiger sharks associated with pupping season appears to increase their presence in nearshore waters used by humans," Meyer said.

The other key factor is that giving birth is draining. Tiger sharks are ovoviviparous, which means their eggs hatch inside the mother's body, and the embryos receive additional nutrition beyond what was in the egg's yolk sac.The sharks also give birth to an average of about 30 pups after 15 to 16 months of gestation.

This means females, while pregnant and after they have given birth, are likely to need to actively forage to recover energy reserves, Meyer said. Other ecological factors may also contribute to the spike in bites, though, he added, such as seasonal increases in the availability of preferred prey, such as large reef fish. Attacks won't be down to the mothers protecting their young, though — once born, tiger shark pups are independent and often stay in shallow areas to avoid being eaten by bigger sharks, including their mother.

The available information suggests an increase in unprovoked shark bites around Hawaii, said Daryl McPhee, an environmental scientist at Bond University in Queensland, Australia, who studies shark attacks but wasn't involved in this study.

"Any seasonal behavioural change that can increase the potential overlap between large species of sharks such as tiger sharks, has the potential to increase the risk of a bite occurring," he told Live Science via email, adding that regardless of the circumstances, the risk of a bite remains low.

Meyer also noted the overall risk of shark bites is extremely low. "The key implication is awareness, not alarm," Meyer said. "Extra caution is advised during this month, particularly for high-risk, solo activities such as surfing or swimming in coastal areas."

Although the October peak revealed in the study is specific to Hawaii and tiger sharks, there may be similar patterns elsewhere in the world, Meyer said. "When large coastal sharks show strong seasonal shifts in habitat use, bite risk can also become seasonal. Other regions and species may experience similar patterns, but the timing and drivers will vary depending on local ecology."

Globally, three large coastal shark species account for most recorded unprovoked bites. These are great white sharks (Carcharodon carcharias), tiger sharks and bull sharks (Carcharhinus leucas), a type of requiem shark.

Bull sharks are thought to be behind a recent spate of bites near Sydney in New South Wales, Australia, with four events within 48 hours, and this period does roughly align with their southern hemisphere summer breeding period.

"Bull sharks along parts of the Australian east coast are more seasonally abundant nearshore and in rivers and estuaries during their reproductive period in the austral summer," McPhee said.

However, other factors may have been more influential to the recent bites in Australia, including a combination of increased summer water use by people, environmental conditions such as storm runoff and reduced water clarity.

"There was a set of environmental conditions that concentrated bull sharks towards the mouth of Sydney Harbour and adjacent beaches," McPhee said. "There was heavy rain in the catchment that would have flushed prey out and it made the water murky. Thus, prime conditions for bull sharks to feed in."

Despite substantial variation in the number of bites across time and in different places, there is a general long-term trend of increasing shark bites, particularly on surfers, McPhee added. In New South Wales there were four recorded bites between 1980 and 1999, while 63 bites were recorded between 2000 and 2019.

Globally the picture is similar, according to data from the Florida Museum. In the 1970s, there were a total of 157 attacks, but that hit 500 in the 1990s and totalled 803 between 2010 and 2019.

Shark quiz

The patient: A 12-month-old boy in Portugal

The symptoms: Shortly after eating different types of fish, the child would develop an odor of rotting fish emanating from his body. The smell was noxious and powerful, especially around his head and hands. He was 10 months old the first time this happened. (The child had been exclusively breastfed as an infant and began eating solid foods at 7 months of age.) His mother temporarily put him on a fish-free diet, but after she reintroduced fish to his meals two months later, the odor returned.

What happened next: When doctors examined the child, they did not detect a fishy smell, though they noted that he had not eaten fish before his medical visit, according to a report of the case. They detected no abnormalities in the boy's neurodevelopment or growth, and laboratory tests showed that his kidneys, liver and thyroid were functioning normally.

The diagnosis: Doctors suspected that the child had developed a rare metabolic disorder called trimethylaminuria, also known as "fish odor syndrome," in which breath, saliva, sweat and urine smell like decaying fish. Rotten fish gets its distinctive smell from a molecule called trimethylamine, and the human body produces trimethylamine from nitrogen-rich foods, such as fish. An enzyme called flavin-containing monooxygenase 3 (FMO3) breaks down trimethylamine in the body, changing it to the odorless compound trimethylamine N-oxide. But if the enzyme isn't working as it should, trimethylamine accumulates in the body and can make a person produce a foul, rotting-fish aroma.

A metabolic pediatrician conducted a molecular analysis of the child's FMO3 gene, which makes the FMO3 enzyme, and found a combination of genetic variants that could disrupt the production of the enzyme, leading to a mild or temporary type of trimethylaminuria.

The treatment: The doctors recommended that the child's parents reintroduce fish to the child's diet in small increments and that they manage any lingering smell with a low-pH soap, which reduces body odors. Over time, the rotten smell after fish meals weakened. By the time the child was 19 months old, he was eating fish five or six times per week without experiencing any malodorous symptoms afterward, and the symptoms had not returned by the time he was 3 years old.

What makes the case unique: There is no treatment or cure for trimethylaminuria; its primary cause is genetic, and in adults the condition is frequently chronic. In this case, the child's temporary bout of trimethylaminuria was likely shaped by a combination of factors, including inherited variants of the FMO3 gene and the immaturity of his metabolism, his physicians wrote in the report.

As the boy's metabolic system matured, the FMO3 enzyme improved its ability to break down trimethylamine. This child's case and others suggest that the causes of trimethylaminuria are more nuanced than once thought and that the disorder varies in severity, according to the report.

Trimethylaminuria is an uncommon disorder, with just a few hundred cases described in medical literature. However, the condition may be underdiagnosed, as people with trimethylaminuria often link their symptoms to personal hygiene habits and do not seek medical treatment for the unusual smell.

This article is for informational purposes only and is not meant to offer medical advice.

A bumpy, pink fish with blue eyes and beard-like appendages has been filmed hovering over the muddy bottom of Monterey Canyon, at a depth of more than 10,700 feet (3,300 meters) off the coast of California.

This strange little snailfish, captured on camera by a group led by researchers at the Monterey Bay Aquarium Research Institute (MBARI), turned out to be one of three newly identified snailfish species living in the perpetual darkness and crushing pressures of the ocean's depths.

Snailfishes are considered unusual even by deep-sea standards. Some have a suction cup of sorts on their stomach that allows them to cling to rocks or hitch rides on other animals. With over 400 known species, snailfishes live in ecosystems ranging from shallow tide pools to the deepest trenches on Earth.

"In addition to being an important part of the ecosystem, snailfishes give us the opportunity to study evolution into the deep ocean within one family," team leader Mackenzie Gerringer, an associate professor of biology at State University of New York at Geneseo, told Live Science.

"By comparing shallow-living snailfishes to their deep-living relatives, we can better understand what adaptations are required for life in the deep sea," Gerringer added.

Scientists discovered the new pink, "bumpy" snailfish species (Careproctus colliculi) in 2019 while using a remotely operated vehicle to explore Monterey Canyon.

Later that year, dives with the human-occupied submersible Alvin found two more new snailfish species at a depth of 13,100 feet (4,000 m): the jet-black "dark snailfish" (Careproctus yanceyi) and the "sleek snailfish" (Paraliparis em), a slender species without a suction disk.

"Distinguishing snailfishes from one another is a puzzle," Gerringer said. "We're looking carefully at multiple features, such as the number of vertebrae and fin rays, the positions of sensory pores, and the shape and size of a specialized suction disk that some species use to stick their bellies to rocks."

The team collected measurements and looked at the different features, along with genetic information, to compare the new specimens with every other known snailfish and find matches. "With each new piece of evidence, it became clear that these three fishes were undescribed species, not previously known to science," she said.

The team's findings, published Aug. 27 in the journal Ichthyology and Herpetology, show not only that snailfish are thriving at these crushing depths but also that a larger, richer biodiversity of the environment remains to be uncovered.

"Accessing the deep oceans is in itself the biggest challenge of this research and requires collaboration between engineers, scientists and ship crews," Gerringer said. "It takes many people to discover a new deep-sea species, all bringing their expertise together to accomplish a shared goal..

"The fact that two undescribed species of snailfishes were collected from the same place, on the same dive, at one of the better-studied parts of the deep sea in the world highlights how much we still have to learn about our planet," she said.

A first-of-its-kind bright orange shark with white eyes has been caught and released in the Caribbean, a new study reveals.

The nurse shark (Ginglymostoma cirratum) had a mysterious condition called xanthism, or xanthochroism, which increases yellow pigmentation in the skin. Researchers have recorded xanthism in several animals, but this is the first definitive case of a nurse shark with the trait. The shark also appears to have albinism, making it even more unusual.

Sports fishers discovered the shark by chance off the east coast of Costa Rica in 2024. Garvin Watson, owner of the Parismina Domus Dei hotel in the village of Parismina, reeled in the shark, which was around 6.6 feet (2 meters) long and swimming 120 feet (37 m) below the surface.

"We could not believe what we had in front of our eyes," Watson told Live Science in an email.

"That orange shark shining with the sunlight was something out of the ordinary," he said. "We did not know that it was going to be a discovery worldwide, recognized by all the biologists of the world."

The fishers photographed the shark, then removed the hook from its mouth and released it back into the Caribbean Sea. Researchers described the event and its significance in a new study published Aug. 1 in the journal Marine Biodiversity.

Related: Do sharks make noises? An accidental discovery might just answer that question

Scientists have documented xanthism in a variety of species, including frogs, birds and fish. While some animals are normally yellow and orange, these colors are more prominent in xanthic individuals of these species.

Nurse sharks are typically yellow to gray-brown. There have been occasional reports of unusual coloring in this species, including albinism — characterized by a complete lack of melanin pigmentation in the skin and iris — and potential xanthism, but a xanthic nurse shark had never been scientifically documented before now, according to the study.

"We were very surprised and excited when we saw the [xanthism] in the photos," study lead author Marioxis Macías-Cuyare, a doctoral candidate in biological oceanography at the Federal University of Rio Grande in Brazil, told Live Science in an email.

The researchers spoke with Watson and studied photos of the shark. They noted that the shark lacked the black irises typically seen in shark eyes, and concluded that it was likely albino as well as xanthic. A 2018 study documented this combined condition, known as albino-xanthochromism, in a ray species (Raja montagui) found in the Irish Sea.

Researchers are still studying the causes of abnormal pigmentation in sharks. Such conditions are typically associated with genetics, but factors such as environmental stress, elevated temperatures and hormonal imbalances may also contribute to different colors, according to the study.

Macías-Cuyare said that xanthism is usually genetic, but more research was needed to understand the conditions influencing the shark's anomalous pigmentation.

The shark's survival is also curious. Animals evolve to be specific colors to better survive in their environments, so being bright orange when the species isn't meant to be would normally be a hindrance. In this case, the shark has made it to adulthood and doesn't appear to have been held back by its unusual color.

"Many factors influence this, such as the environment, but everything remains speculative until the variables that could influence this genetic condition are tested," Macías-Cuyare said.

Never-before-seen footage has captured thousands of catfish climbing a waterfall in southern Brazil — the first detailed observation of the species migrating.

Bumblebee catfish (Rhyacoglanis paranesis) get their name from the black spots on their orange bodies and their tiny size, with the fish reaching just 3.5 inches (89.2 millimeters) in length. The small jumping fish were filmed scaling slippery rocks between 3.3 and 13.1 feet (1 to 4 meters) high behind a waterfall on the Aquidauana River.

Scientists know virtually nothing about this rare fish species' behavior. But in 2024, members of the Environmental Military Police from Brazil’s Mato Grosso do Sul State noticed the spectacle before calling in a team of scientists to document it. Their findings were published Aug. 8 in the Journal of Fish Biology.

The genus Rhyacoglanis encompasses nine species of small catfish that live throughout the Amazon, Orinoco, and La Plata river basins. "[This genus] is rarely collected and even less frequently observed," Manoela Marinho, a biologist at the Federal University of Mato Grosso do Sul in Brazil and first author of the new study, told Live Science in an email. "That's why the large aggregation we reported is so remarkable, as there had been no prior indication that such behavior was part of this genus's natural history."

In the new paper, the scientists report that the bumblebee catfish only climbed later in the day: in the hotter afternoons the fish found shade under rocks. But at around 6 p.m. local time, as the sun was setting, thousands of them began their ascent.

Starting in small pools connected to the river, the catfish jumped up steep and vertical stretches of rock. On flat rocks, there were so many fish that they were seen climbing on top of each other. In their climbing frenzy, some of the catfish even clambered up the scientists' plastic bucket.

Related: Gigantic, 9.4-foot-long catfish is the largest ever caught

The catfish climbed by keeping their fins straight, and using side-to-side rocking and tail-flipping motions to propel themselves forward. The scientists also speculate the fish might create a suction mechanism to stick to rocks as they climb by forming a small cavity between the body and the rock — a strategy shared by some other fast-flowing river fish like stream loaches and Andean climbing catfishes.

The research team doesn't know why the catfish were climbing the waterfall, but they suspect they were migrating upstream to reproduce. The climbing group included males and females, most of them adults. This behavior also began in November, the start of the rainy season, after a particularly dry winter.

"All the signs point to this being a reproductive gathering," said Marinho. "It happened right after a long and severe drought in the region, and the sudden rise in water levels seems to have triggered the species to spawn, bringing together a massive concentration of fish that had never been seen before."

Small fish migration behavior is poorly understood in Brazilian rivers, according to the researchers, because most studies focus on larger fish species important to the fishing industry. The lack of information on smaller fish species in the region could also be because migrations occur quickly and under very particular environmental conditions, making them easy for scientists to miss.

The discovery shows how important river habitats are to small fishes' life cycles, according to the researchers, in light of river damming projects that threaten to fragment Brazilian river habitats and hinder fish migration.

"Recording and sharing this type of behavior…underscores the need to preserve natural habitats, especially fast-flowing streams," Marinho said. "These habitats are often submerged by hydroelectric reservoirs, causing species adapted to these environments to disappear entirely."

A rocket-like jellyfish, a majestic Komodo dragon and a dangerous surfing encounter are just a few of the stunning photographs captured by the finalists for the Ocean Photographer of the Year 2025 competition. The competition includes categories such as Impact and Hope, which have solicited breathtaking photographs that capture diverse forms of marine life and human interaction with the ocean.

The overall and category winners of the contest, hosted by Oceanographic Magazine and watch company Blancpain, will be announced in September. But all of the finalists' photos emphasize the need to protect the planet.

"In the midst of a deepening climate and biodiversity crisis on our blue planet, ocean photography has never been more important," Will Harrison, director of Ocean Photographer of the Year, said in a statement from the organization. "These images are far more than just beautiful; they are powerful visual testaments to what we stand to lose, and they remind us of the urgent need for protection."

Here are some of the gorgeous photos.

Synchronized swimmers

Photographer Yuka Takahashi, a finalist in the "Young" category of the competition, captured a pair of synchronized humpback whales in French Polynesia swimming through rays of sun. "These two humpback whales are always seen together, and I was fortunate to capture this rare moment of synchronicity," Takahashi said. "To me, this photo reflects the strong bond between them while also revealing their playful and curious personalities."

Warm bath

In this image, snapped by "Wildlife" category finalist and photographer Suliman Alatiqi, a Komodo dragon (Varanus komodoensis) looms over an Indonesian shore. Because Komodo dragons are cold-blooded, they rely on cold water or mud to regulate their body temperature in the summer. They also travel across seabeds to search for food and mates.

Related: Ocean Photographer of the Year 2024: See stunning photos of hungry whale, surfing seagull, freaky fish babies, land-loving eel and adorable toxic octopus

Collateral damage

Photographer Natnattcha Chaturapitamorn snapped this image of fishers unloading their catches at a Bangladeshi harbor during sunrise, which is a finalist in the "Impact" category.

"Amidst this industrious energy, the presence of an endangered species serves as a reminder of the urgent need to protect marine biodiversity," Chaturapitamorn said. "As global fish stocks decline, safeguarding threatened species like this is vital, not only for ecological balance but for the long-term sustainability of fishing communities that depend on the ocean’s bounty."

Stranded

On July 1, wildlife veterinarians received a call about a humpback whale stranded on an Australian beach, and photographer Craig Parry documented the harrowing scene from above. For 15 hours, rescue teams and other members of the community worked to save the whale but were unsuccessful.

"While the outcome was heartbreaking, witnessing the collaboration and compassion shown by multiple agencies and volunteers was incredibly moving — a powerful reminder of what can be achieved when people come together with a shared purpose," said Parry, whose photo is a finalist in the "Human Connection" category.

School of fish

This mesmerizing image, taken in Indonesia by photographer Kim Hyeon Min, captures a school of juvenile fish circling around a tower of coral and is a finalist in the "Hope" category. The vibrancy of the coral suggests it has been unaffected by bleaching and is still able to host a miniature ecosystem for surrounding creatures. "In a time when marine ecosystems are rapidly disappearing, this image is a reminder of what we still have — and a hopeful glimpse of what we must protect for the future," Hyeon Min said.

Otherworldly jellyfish

Jellyfish are often described as alien-like, and this ethereal image captured in Spain by photographer Toni Bertran Regàs takes that comparison to new heights with this finalist in the "Fine Art" category.

"I've always been fascinated by the resemblance between jellyfish and space rockets," Bertran Regàs said. "I was looking for a photograph that conveyed that connection: a rocket leaving Earth. To do this, I used a fisheye lens and took the photo just as the sun was rising. Snell's Window" — an underwater optical phenomenon — "helped me create the Earth, the particles were the stars, and the sun luckily appeared behind it."

Monster waves

Photographer Ben Thouard, a finalist in the "Adventure" category, captured a day of rough seas in Nazaré, Portugal. Though the water was too dangerous for many surfers, two gave it a go. Despite the difficulty of photographing between huge waves and through salt water in the air, Thouard eventually shot this moment.

A deep-sea expedition off the coast of Argentina has captured stunning footage of more than 40 never-before-seen species.

One unexpected star of the show is a plump sea creature that has been dubbed the "big-butt starfish" for its uncanny resemblance to Patrick Star from "SpongeBob SquarePants."

During the remotely operated vehicle (ROV) SuBastian's dives in Argentina's Mar del Plata submarine canyon, which have been running since July 23, scientists aboard its accompanying research vessel provide a high-definition livestream, with real-time commentary on rarely seen deep-sea life. The dives have revealed carnivorous sponges, translucent fish, vividly colored rays and corals that have never been documented in the South Atlantic, a biodiversity hotspot that remains largely unexplored.

The sea star, which has become a viral hit on social media, belongs to the genus Hippasteria, which is known for its thick central disc and short, stubby arms. During the livestream, viewers interacting via chat affectionately nicknamed it "estrella culona" — Spanish for "big-butt star."

Argentine scientists involved with the expedition have offered a few hypotheses for the creature's attention-grabbing anatomy. The starfish may simply be well fed; they are voracious carnivores. Or, its rounded appearance could be the result of gravity, as it was filmed on a vertical surface with its central disc hanging downward, creating the illusion of glutes.

Starfish don't have rear ends like humans or other bilaterally symmetrical animals do. Instead, they exhibit radial symmetry, with a mouth located on the underside of the central disc. That lower, or "oral," surface lies pressed against the seafloor, where feeding occurs. The anus is located in the center of the upper, or "aboral," surface, which is what a diver would see first when approaching the animal.

Related: 'A disembodied head walking about the sea floor on its lips': Scientists finally work out what a starfish is

"Although starfish do have a complete digestive system and an anus, it's not in the location people are pointing to on social media," Mariela Romanelli, a biologist and curator of the invertebrate collection at Argentina's National Museum of Natural Sciences, told local news site Infobae in Spanish. "Still, the resemblance to Patrick Star's butt is pretty hilarious."

The big-butt starfish isn't the only creature from the expedition, led by scientists from the National Scientific and Technical Research Council and the Schmidt Ocean Institute, that has charmed the public. Another deep-sea creature captured on camera was a violet sea cucumber, belonging to the genus Benthodytes, whose plump body and purple hue earned it its name "Batatita"" ("Little Sweet Potato"). The specimen was collected by the ROV and is alive and well at the surface, expedition scientists said.

So far, the expedition has documented at least 25 species of fish, both bony and cartilaginous; carnivorous sponges that have never been recorded in the South Atlantic; and crustaceans and other invertebrates that are specially adapted to the pitch-black depths.

The livestream, broadcast for the first time from nearly 13,100 feet (4,000 meters) below sea level, continues through Aug. 10 and can be viewed on the Schmidt Ocean Institute's official YouTube channel.

In 2019, shark tagger Keith Poe was working off the coast of California when he hooked a surprisingly big "black mako" shark. The shark appeared larger and darker than shortfin makos (Isurus paucus), which are generally dark blue or gray with white undersides.

This sighting is the basis of the new Shark Week show "Black Mako of the Abyss," where a team sets out to find more of these black makos in an attempt to work out exactly what Poe caught six years ago. Suggestions for the creature’s unusual appearance and size include genetic mutations and the potential for shortfin makos hybridizing with another species.

In the episode, Poe works with environmental scientist Kendyl Berna, marine biologist Tristan Guttridge and shark attack survivor Paul de Gelder as they travel 40 miles (64 kilometers) off the coast of California to lure ocean predators in the hope of attracting black makos. Their ultimate goal is to obtain tissue samples to conduct genetic analysis and find out what the mysterious animals really are.

During the show, the team lures sharks using a helicopter carrying hundreds of gallons of chum. They later deploy a white shark decoy to see if any makos interact with it — with the latter drawing out an aggressive, unusually dark mako shark.

This shark, like that in Poe's original video, appears to have shortfin and longfin features, leading the team to speculate that it could be a longfin mako (Isurus paucus), or longfin/shortfin hybrid.

Unlike shortfins, longfin mako sharks are more elusive, living in deeper waters further out from coastlines. As a result, they're less understood than their shortfin cousins, with big questions about their range and habitat — although sightings off California are particularly rare. Physically, their bodies are more slender than shortfins, and they have longer pectoral fins and darker coloration.

To establish whether the black makos are potentially longfins, the team released bait that encourages the sharks to breach, so they can see their size and physical characteristics more clearly. The captured footage revealed several shortfins, but one appeared to have pectoral fins far longer than the average, again raising the idea of a shortfin/longfin hybrid.

Shark hybridization is not unheard of. In 2019, scientists reported scalloped hammerhead (Sphyrna lewini) and Carolina hammerhead (S. gilberti) hybrids in the western North Atlantic, while in Australia in 2011, researchers found hybrids of the black-tip whaler shark species Carcharhinus tilstoni and C. limbatus.

While the Shark Week team tried to get samples from their black makos to see if they are hybrids, the sharks were too fast.

Experts say the potential for shortfin/longfin hybridization is unlikely. There is no evidence of the two species mating, and even if they did, any hybrid offspring would likely be sterile.

"Different species with naturally overlapping ranges typically don't hybridise, if they did and the offspring were viable, the species would merge back into one," Jess A.T. Morgan, principal scientist at the animal science division of the Department of Primary Industries, Queensland, Australia, told Live Science in an email.

"Natural hybridisation can and does occur in nature, but often only in restricted regions of species overlap called hybrid zones," Morgan added. "Hybrids occasionally do survive in nature and are able to reproduce (this appears to be the case with black tip sharks) but in most cases they will be less fit than the pure species so don't pass on their DNA."

Morgan was a co-author on the blacktip hybrid study from 2011, and said DNA evidence is needed to establish if a weird-looking shark is a hybrid: "One thing we know about sharks is that differences in external appearance can be misleading," she said. "A lot of species can be easily confused, particularly if they belong to the same genus and are not fully grown."

Berna said another possibility is that the black makos are just longfins that are coming closer to the coastline, or they are shortfins with mutations that help them hunt in deeper waters, such as darker skin. Environmental changes could also potentially explain shifts in shark ranges — for example, climate change has been linked to tiger sharks (Galeocerdo cuvier) moving northwards over the last few decades.

"I think it's possible that these black makos that we're seeing are actually just longfin makos," Berna told Live Science. "When you see a mako that isn't supposed to be in these waters, and isn't very documented in these waters, looking funny, then you would think 'wow, that's a strange looking shortfin mako,' when in reality, maybe it's actually a longfin, just in a different geographic range than what's sort of accepted by science."

Longfin makos tend to be found in more tropical waters, and are known off the coast of Mexico — but as ocean temperatures heat, it's possible their distribution is also shifting north, Berna said. "Global warming, climate change — that's constantly changing distributions of animals, as well as overfishing [changing] where they have availability of prey and food sources. There's a lot of reasons that animals, and sharks in particular, can change their geographic distribution and ranges."

Douglas Adams, a researcher at the Florida Fish & Wildlife Conservation Commission, said genetic analyses would be needed to answer these questions about the unusual makos found by the group. "Many questions remain regarding the range and habitat use of longfin makos," he told Live Science in an email. "The ecology and biology of longfin makos are not well understood, but the ranges of many other fish species have been shifting with ocean warming and other factors."

Berna said they are still hoping to get a sample to find out what these black makos are. "A genetic sample would be the absolute, highest form of confirmation that we could get. That, ultimately, is the goal."

Shark Week 2025 is almost here, offering new shows full of thrills to celebrate its 37th year. Once again, we've put together a handy guide on how to watch Shark Week 2025, including air times, where you can watch, and the standout shows worth keeping an eye on.

Despite recent years having big names like Dwayne "The Rock" Johnson and Jason Momoa on board to lead the proceedings, it appears Discovery is going with a leaner (and hopefully meaner) approach in 2025. Shark Week has been around since 1988, and it's meant to help us celebrate and understand these beautiful creatures, rather than build up fear.

We'll admit it hasn't always lived up to that mantra, but these days Discovery does a good job of showing sharks to the world while ramping up the fun factor for the most part.

The hottest shows lined up to chomp on during Shark Week 2025 include "Dancing with Sharks" — a new Shark Week special — and "Air Jaws: The Hunt for Colossus" (now that's a wild title).

When is Shark Week 2025?

• July 20 – July 26

Shark Week 2025 starts on July 20 (Sunday) and runs until July 26 (Saturday).

The official kick-off takes place on Sunday, July 20, at 8 p.m. ET/PT on Discovery, with the content also available to stream on HBO Max.

"Dancing With Sharks" — hosted by Emmy Award-winning TV personality Tom Bergeron — will lead the charge, but Discovery's full July 20 schedule suggests a substantially larger offering of shark-related shows throughout the whole day.

Where to watch Shark Week 2025: TV & Streaming

Shark Week airs exclusively in the US on the Discovery Channel, which is available on most cable TV services.

If you want to watch Discovery but don't have traditional cable, you can get it via the new wave of "cord-cutting" streaming platforms, which offer cable channels in an online subscription package.

Sling TV is one of the best, with Discovery on the Blue package for $45 per month – half price for your first month. You can also watch Discovery on Hulu + Live TV, DirecTV Stream, and YouTube TV.

To watch on demand, you can get Shark Week content on HBO Max, ($9.99 per month), which is Discovery’s main streaming platform since the Warner Media-Discovery merger in 2022.

We also believe Discovery+ will offer the full Shark Week 2025 offerings at a later date. As far as we know, you can watch most of 2024's Shark Week content on there.

How to watch Shark Week outside the US

Shark Week 2025 is only airing live in the U.S.

If you're stuck abroad during Shark Week and can't access one of the above streaming options in your current location, we have a solution for you: a VPN.

A Virtual Private Network will allow you to access geo-restricted content by bouncing your connection to a server based in that country. This means that you can access all of your U.S.-based streaming services no matter where you are in the world.

There are many VPN services out there, but NordVPN is the best all-round option, according to our expert colleagues at Tom's Guide, and it's a good time to take out a subscription.

Offer applies in the US, Canada, and UK. To take advantage, follow the deal, select a discounted two-year plan, and the four-month bonus will be added automatically to your selection. Once you've taken out the plan and reached the end of the 30-day free trial period, your Amazon gift card (amount depends on selected plan) will land in your inbox.

Shark Week 2025 schedule

Below you can find the full Shark Week 2025 schedule, which includes every big show airing during Shark Week plus the dates & times to catch them live. All of them can be watched on HBO Max any time after the air date. More shark-related shows will be part of the complete Discovery schedule throughout Shark Week.

“Jaws vs. Mega Croc”

Right after “Great White Sex Battle,” we highly recommend not skipping the silly-sounding but somewhat compelling “Jaws vs. Mega Croc,” which gives viewers “a CGI fight to the death between two of the biggest and baddest apex predators in the water — the great white shark and Nile crocodile.

► 9pm ET/PT on Monday, July 21.

"Great White Sex Battle"

"In a Shark Week first, male and female great white sharks compete in a series of challenges to determine which sex is the superior predator in the waters off the coast of New Zealand," the press release says.

► 8pm ET/PT on Monday, July 21.

"Air Jaws: The Hunt for Colossus"

If you're into shows and documentaries following researchers around as they chase a specific animal of mighty proportions and/or special skills, you should be interested in "Air Jaws: The Hunt for Colossus," which, as you might expect, focuses on the search for a great white shark known as "Colossus" who has been missing for years.

► 9pm ET/PT on Sunday, July 20.

"Dancing With Sharks"

Hosted by Emmy winner (and former "Dancing With the Stars" host) Tom Bergeron, "Dancing With Sharks" is a brand-new Shark Week 2025 special that features "an unprecedented underwater dance competition between expert divers and their shark partners," which is something we don’t see often.

► 8pm ET/PT on Sunday, July 20.

Discovery has adjusted recent Shark Weeks to a 20-hour format which might feel a bit small for some viewers, but there’s plenty of exciting and informative programming to watch every day of the event. We suggest carefully studying the full schedule — straight from Discovery — that we shared above, but we’ve picked out some potential standouts leading the pack that you should keep an eye on.

Shark Week 2025: Best shows to watch

What is Shark Week?

Shark Week 2025 is a week-long extravaganza of original content about, you guessed it, sharks.

Shark Week was originally created to spread awareness about conservation efforts and correct misconceptions about sharks in a post "Jaws" world. Over time, however, it grew in popularity and became a recurring hit for Discovery. As a result, more entertainment-oriented and sometimes fictional programming took over.

By the 2010s, criticism of its most dramatic programs, many of which hurt the reputation of sharks, led to professionals in the science blogger community as well as scientists calling for a boycott of the network.

As accusations of junk science and fake stories piled up, Discovery vowed in 2015 to remove this type of programing from future Shark Week lineups. While dubious shows like "Megalodon: The Monster Shark Lives" are rarer nowadays, you can tell from the spicy titles that even the most scientifically accurate programs are designed to attract as many eyes as possible.

Shark Week also offers more than just shows. There’s now a podcast — captained by environmental journalist and comedian Kasha Patel — to listen to. Discovery is also highlighting plenty of educational shark-centric articles, facts, and videos to get people interested in these animals.

We test and review VPN services in the context of legal recreational uses. For example: 1. Accessing a service from another country (subject to the terms and conditions of that service). 2. Protecting your online security and strengthening your online privacy when abroad. We do not support or condone the illegal or malicious use of VPN services. Consuming pirated content that is paid-for is neither endorsed nor approved by Future Publishing.

Sharks can be formidable predators, but when they're flipped upside down, many species enter a trance-like state, known as tonic immobility, and are as helpless as a beetle on its back.

Tonic immobility is "as close to hypnotising a shark as you can get!" Joel Gayford, a doctoral candidate of marine ecology at James Cook University in Australia, told Live Science in an email. "The animal completely stops swimming, and the only movement it's making is slow rhythmic breathing."

But what happens when a shark enters this state? And why do sharks freeze when turned belly-up?

During tonic immobility, a shark experiences a decrease in sensory responsiveness, cardiac rate and blood pressure, as well as analgesia, meaning a decrease in its sensitivity to pain, Abraham Miranda-Páez, a researcher at the National School of Biological Sciences in Mexico city, told Live Science in an email.

For the shark species that go into tonic immobility — including great white sharks (Carcharodon carcharias), lemon sharks (Negaprion brevirostris) and gray nurse sharks (also known as a sand tiger shark, or Carcharias taurus) — this freeze response "can be induced when the shark is flipped over or by stimulating the snout (home to lots of electroreceptors called the ampullae of Lorenzini), Jillian Morris, founder of Sharks4Kids, a Florida-based nonprofit, told Live Science in an email.

By putting sharks into this snoozing state, scientists can conduct research safely while reducing stress for the animal.

"We can make a small incision and insert an acoustic tag safely and humanely, without the need for special equipment," Morris said. "It's always done very quickly, and then the shark is flipped back over."

Related: Can turtles really breathe through their butts?

How tonic immobility helps sharks survive

But sharks didn't evolve this trait to help scientists take samples, so what's going on?

There are a few leading theories. According to a 2023 study in the journal Environmental Biology of Fishes, tonic immobility could be for self-defense, courtship or protection from sensory overload. "The consensus among the scientific community is that tonic immobility is a passive defensive response," said Miranda-Páez, co-author of the study.

In other species, playing dead can be helpful. Dice snakes and fire ants pretend they've popped their clogs when predators attack, while female dragonflies and European common frogs fake their own death to avoid sex.

But not everyone is convinced that paralysis would be effective protection for sharks. "This explanation doesn't work very well for sharks," Gayford said. "Most shark predators would not be deterred by a motionless target."

In some instances, it's a clear disadvantage — orcas have worked out that they can incapacitate sharks to overpower them and gobble down their nutrient-rich livers.

Sharks go into this state during sex, said Morris, who has observed nurse sharks mating. "The male flips the female over, and she enters tonic immobility before copulation." However, males are affected too, "so mating does not fully explain why this phenomenon occurs," she added.

A 2025 study in the journal Reviews in Fish Biology and Fisheries suggests that tonic immobility has no purpose and is just an evolutionary hangover. "We actually found that tonic immobility has been lost independently several times throughout the evolutionary history of sharks and rays," said Gayford, a co-author of the study.

Many of the species that don't have this response probably lost it for a reason, Gayford said. Typically, small coral-dwelling sharks spend lots of time looking for food in tight spots, where they could get stuck. "If these species were to go into tonic in this situation, it could have deadly consequences," Gayford said.

For now, scientists don't have enough data to conclusively say what purpose tonic immobility serves. "There are many theories, none of which are fully understood or thoroughly supported," Morris said.

Editor's note: This story was updated at 9:23 a.m. ET on July 25 to correct the title of Abraham Miranda-Páez.

Shark quiz: How much do you know about these iconic ocean superstars?

Pacific spiny lumpsuckers' tiny, plump bodies and adorable appearance make them essentially wild kawaii. They are awkward swimmers, so to avoid being swept off by currents in their coastal homes, their pelvic fin has evolved to act as a suction cup, enabling them to anchor themselves to a stable surface.

At just 1 to 3 inches (2.5 to 7.6 centimeters) long, they are the smallest of the 27 species of lumpsuckers, also called lumpfish, some of which can grow as long as two feet (61 cm). Lumpfish are in the same order, Scorpaeniformes, as blobfish, sea robins and stonefish.

Pacific spiny lumpsuckers are small, globular fish with extra-small fins which they flap wildly to get around. It makes them able-but-awkward swimmers. Living close to the coast and facing the pulls of tides and strong currents, their pelvic fins are fused to form a surprisingly strong sucker disc which lets them attach to rocks, coral or kelp, and, in aquariums, even to the side of a tank.

These sucker discs are a bit fearsome to look at from the underside – like a lamprey with a circle of human teeth. That's because, like our teeth, those of the Pacific spiny lumpsucker are made from enamel. The disc also emits a green and yellow glow — though the reasons for this are not known.

Males are usually red (see “concerned strawberries”) and glow red under ultraviolet light, while females are usually green to brown and don't glow under UV rays.

When it's time to reproduce, only the males settle down. They stake out a territory, usually a shallow depression in warmer water where the females lay their eggs. The male fertilizes them and then she leaves and he tends to and guards the next generation from predators.Young lumpsuckers don't yet have a defense the adults have — rows of enamel bumps called odontodes covering their bodies, including that toothy-looking circle on their undersides.

Eventually, they will grow odontodes in spiral rows all around their bodies to protect them against predators and collisions with rough surfaces.

As it drifts through the inky blackness of the "midnight zone" in the deep sea, the pelican eel undulates its narrow, whiplike tail and long, snakelike body. It's hard to imagine its slender form consuming large prey — that is, until the eel unfolds its jaw like an umbrella and yawns its cavernous sac of a mouth.

Like its pelican namesake, this eel has an elastic pouch under its lower jaw that balloons open as its jaw gapes wide, engulfing anything unlucky enough to be swimming close to the eel's head. And with an expandable throat and stomach, a pelican eel can scoop up animals larger than its own body, swallowing prey whole while filtering the mouthful of water through its teeth and gills.

The pelican eel, also known as a gulper eel, measures about 3.3 feet (1 m) long and has deep black skin that absorbs nearly all light, making it practically invisible in the dark depths of the ocean.

The hinged lower jaw of a gulper eel is about one-quarter as long as its entire body. While its mouth is enormous, it has tiny eyes and very small teeth. It also lacks scales and a swim bladder, which fish use to regulate their buoyancy. Its pectoral fins are so reduced that they are barely visible at all.

As a result, the pelican eel is a poor swimmer and hunter. But its gaping maw makes the eel an exceptional opportunistic predator. A light organ, or photophore, at the tip of the eel's tail glows pink or bright red in the dark water and is thought to act as a fishing lure, attracting prey close to the eel's massive trap of a mouth.

A pelican eel's elastic stomach can stretch significantly to hold a hefty meal. In 2023, scientists were exploring waters near Costa Rica using a remotely operated vehicle, when they spotted a pelican eel that had recently eaten. As it swam away from the camera, its belly was visibly and dramatically distended. Its shape hinted that the eel's recent dinner was a squid, the researchers reported.

When male pelican eels become sexually mature, their jaws weaken and they lose teeth but grow larger olfactory organs, improving their sense of smell. This likely helps them find mates. But as is the case with many deep-sea dwellers, there is still much to be learned about this species' habits and behaviors in the wild.

Our sensitive teeth originally evolved from the "body armor" of extinct fish that lived 465 million years ago, scientists say.

In a new study, the researchers showed how sensory tissue discovered on the exoskeletons of ancient fish is linked to the same "genetic toolkit" that produces human teeth.

"This shows us that 'teeth' can also be sensory even when they're not in the mouth," study co-author Yara Haridy, a paleontologist and evolutionary biologist at the University of Chicago, said in a statement. Haridy and colleagues published their findings Wednesday (May 21) in the journal Nature.

Originally, the researchers set out to identify the earliest vertebrate in the fossil record, seeking out fossil specimens from the Cambrian and Ordovician periods (541 million to 443 million years ago). One telltale sign of a vertebrate species is the presence of internal tubules for dentine, a calcified tissue that is found just underneath the enamel in human teeth, but that is found in external bumps in ancient fish armor.

While using high-resolution CT scans to investigate the jawless "first fish" species Anatolepis heintzi, the researchers discovered what looked like pores filled with dentine. To confirm this, they compared A. heintzi to a coterie of ancient fossils and modern marine life.

But as they looked more closely, they realized that the supposed dentine-lined pores were actually more like the sensory organs on the shells of crabs. A. heintz was therefore an ancient invertebrate arthropod — not a vertebrate fish.

Related: Scientists discover new 15 million-year old fish with last meal fossilized inside its stomach

Clearing up the confusion about the categorization of A. heintz led to an important new insight: Ancient vertebrates like fish and ancient arthropods were making the same mineralized tissue to help them sense their environment. Eventually, that mineralized tissue evolved into dentine — and into our sensitive teeth.

The new study supports the idea that sensory structures evolved on exoskeletons at least 460 million years ago, and then later in evolutionary history, animals used the same "genetic toolkit" to make teeth.

"Viewed through this evolutionary lens, the fact that teeth in the mouth are extremely sensitive is less of a mystery, and more a reflection of their evolutionary origins within the sensory armor of early vertebrates," the researchers wrote in the study.

Evolution quiz: Can you naturally select the correct answers?

Sharks have long been thought to be mute, relying on stealth to hunt their prey and avoid predators. But now, sharks have been recorded making sounds for the very first time.

The new recordings reveal that rig sharks (Mustelus lenticulatus) — small, bottom-dwelling sharks native to New Zealand — emit distinct clicks when handled by researchers underwater. These sounds were consistent and repeated across multiple individuals, and were potentially tied to distress or defensive responses, according to a study published Mar. 26 in the journal Royal Society Open Science.

The recordings represent the first known case of a shark actively producing sound. "Sharks have sensory systems that are more refined than their hearing, like their electroreceptors, their smell and the way they propel themselves through the water," study lead author Carolin Nieder, a researcher at the Woods Hole Oceanographic Institution, told Live Science. "But I think the original notion that we had that sound isn't important at all is also likely not true."

Ten juvenile rig sharks were observed making sounds by accident during routine behavioral experiments at the University of Auckland's Leigh Marine Laboratory. When briefly handled by researchers underwater, all 10 sharks produced audible clicks.

Related: Octopus spotted riding on top of world's fastest shark

These clicking sounds were very frequent during the first few handlings but then stopped as the experiments progressed, Nieder said. "Maybe they weren't afraid for their lives anymore," she said, adding that in the wild, loud clicks may serve as a split-second distraction for juvenile sharks to make their escape when they are seized by predators.

Most sharks are thought to be silent because they lack swim bladders — air-filled sacs commonly used by fish to make sounds. MicroCT scans and 3D reconstructions of rig sharks also revealed no obvious sound-producing organs or structures.

The team proposed that the sounds could be coming from the sharks snapping their teeth.

Rig sharks have broad, blunt teeth arranged in tightly packed, plate-like formations, which are ideal for crushing hard-shelled prey like crabs. This "pavement dentition," may also serve a second function of producing noise when the jaws snap shut, the researchers said.

However, Nieder noted that without direct observation of the sharks' jaws during click production, the mechanism remains speculative.

Each click lasted around 48 milliseconds, with volumes sometimes exceeding 155 decibels, which is comparable to shotgun blast.

Roughly three-quarters of the clicks were single bursts, while the rest were short double-clicks. The scientists observed that about 70% of these clicks were accompanied by calm, swaying body movements, but a few occurred without any visible motion at all.

Whether the clicking is an accidental byproduct of handling or a purposeful behavior remains unknown.

The sharks' own hearing range is largely below 1 kilohertz, far lower than the frequencies of its clicks, meaning it's unlikely the clicks are meant for communicating with other sharks.

However, some known predators of rig sharks, such as New Zealand fur seals (Arctocephalus forsteri), are sensitive to higher frequencies and might be startled or confused by the sharp clicks.

Several species of rays and skates — close relatives of sharks — are also known to produce clicks when disturbed by divers. These sounds are thought to serve as warning signals or distress calls.

Nieder said future studies could target closely related shark species to investigate whether they are also capable of making noises, and whether they make noise in response to stress.

Adrian Gutteridge, a shark biologist with the IUCN Shark Specialist Group who was not involved in the study, said more research will be needed to establish what the shark clicks are for, and what they could mean.

"It's too early to tell whether it's a response, kind of saying, 'go away,' or if [it's] just their nervous system is firing off which just happens to make their teeth and jaws click," he told Live Science.

Editor's note: This article was first published on March 26, 2025.

Shark quiz: How much do you know about these iconic ocean superstars?

Fish that survive in extreme deep-sea environments have developed the same genetic mutation despite evolving separately and at different times, researchers say.

The scientists also found industrial chemicals in fish and in the ground in the Mariana Trench, meaning human-made pollutants can reach some of the deepest environments on Earth.

Deep-sea fish have developed unique adaptations to survive extreme pressure, low temperatures and almost complete darkness. These species adapt to extreme conditions through unique skeletal structures, altered circadian rhythms and either vision that's extremely fine-tuned for low light, or are reliant on non-visual senses.

In a new study, published March 6 in the journal Cell, researchers analyzed the DNA of 11 fishes, including snailfish, cusk-eels and lizardfish that live in the hadal zone — the region about 19,700 feet (6,000 meters) deep and below — to better understand how they evolved under such extreme conditions.

The researchers used crewed submarines and remotely operated vehicles to collect samples from about 3,900 to 25,300 feet (1,200 to 7,700 m) below the water's surface, in the Mariana Trench in the Pacific and other trenches in the Indian Ocean.

Tracing the evolution of deep-sea fishes, the researchers' analysis revealed that the eight lineages of fish species studied entered the deep-sea environment at different times: The earliest likely entered the deep sea in the early Cretaceous period (about 145 million years ago), while others reached it during the Paleogene (66 million to 23 million years ago), and some species as recently as the Neogene period (23 million to 2.6 million years ago).

Despite different timelines for making the deep sea their home, all the fishes studied living below 9,800 feet (3,000 m) showed the same type of mutation in the Rtf1 gene, which controls how DNA is coded and expressed. This mutation occurred at least nine times across deep-sea fish lineages below 9,800 feet, study author Kun Wang, an ecologist at Northwestern Polytechnical University, told Live Science in an email.

This means all these fishes developed the same mutation separately, as a result of the same deep-sea environment, rather than as the result of a shared evolutionary ancestor — showing just how strongly deep-sea conditions shape these species' biology.

Related: How deep is the Mariana Trench?

"This study shows that deep-sea fishes, despite originating from very different branches of the fish tree of life, have evolved similar genetic adaptations to survive the harsh environment of the deep ocean — cold, dark, and high-pressure," Ricardo Betancur, an ichthyologist at the University of California San Diego who was not involved in the new study, told Live Science in an email.

It's an example of convergent evolution, where unrelated species independently evolve similar traits in response to similar conditions. "It's a powerful reminder that evolution often reuses the same limited set of solutions when faced with similar challenges — in this case, adapting to the extreme conditions of the deep sea," Betancur said.

The expeditions also revealed human-made pollutants in the Mariana Trench and Philippine Trench. Polychlorinated biphenyls (PCBs) — harmful chemicals used in electrical equipment and appliances until they were banned in the 1970s — contaminated the liver tissues of hadal snailfish, the scientists discovered.

High concentrations of PCBs and polybrominated diphenyl ethers (PBDEs), flame retardant chemicals used in consumer products until they fell out of popularity in the early 2000s, were also found in sediment cores extracted from more than 32,800 feet (10,000 m) deep in the Mariana Trench.

Previous research has also found chemical pollutants in the Mariana Trench, as well as microplastics in the deep sea. The new findings further reveal the impacts of human activity even in this ecosystem that's so far removed from human life.

Editor's note: This article was originally published on March 28, 2025

Mariana Trench quiz: How deep is your knowledge?

Shocking new footage shows a pair of bloodsucking parasites latched onto the head of a deep-sea rattail fish.

In the video, which the Schmidt Ocean Institute shared in a Facebook post, two copepods — small crustaceans — are positioned on either side of their host's head. Long egg sacs attached at the back of the parasites make it look like the fish is sporting a pair of pig tails.

"They feed on blood and fluids from their host using their scraping mouth parts that are embedded in the muscle of the fish," James Bernot, an evolutionary biologist at Smithsonian National Museum of Natural History who was not on the expedition, told Live Science in an email.

Scientists captured the footage at a depth of 1,604 feet (489 meters) during an expedition to examine the seafloor and biodiversity of the South Sandwich Islands, a chain of 11 subantarctic volcanic islets in the South Atlantic Ocean.

The copepods are a species called Lophoura szidati, and are latched onto the head of a rattail fish from the genus Macrourus, representatives wrote in the Facebook post.

Related: Watch bright red blood-sucking parasite feast on gulper eel in rare, deep-sea footage

Macrourus are commonly known as grenadiers or rattails because of their large heads and slender tails. These widespread deep-sea fish occupy the cold waters of the North and South Atlantic Ocean, as well as the Southern Ocean that borders Antarctic waters, and can be found at depths from 1,312 to 10,450 feet (400 to 3,185 m).

Knowledge of deep-sea fish parasites in Antarctic waters is scarce, but L. szidati, is one of the most common parasites found on Macrourus species in this region.

L. szidati is part of the family Sphyriidae. Females of this species have been observed using their mouth parts to bore into the bodies of various fish and feed on their host's muscle tissue.

"These copepods are mesoparasites, meaning they are partly inside and partly outside of their host," Bernot said, adding that in the video the middle and back end of the copepods stick out of the fish, while the anterior, or head-end of their body is embedded in the fish.

Many copepod parasites have multiple stages in their life cycle and typically find their hosts while in their larval stage. These tiny larvae bury themselves within the host's skin and begin feeding. During this time they metamorphose and develop anterior holdfasts that serve as anchors to keep them attached to their hosts as they grow.

In the video, each parasite carries a pair of sacs containing hundreds of eggs. "Copepods are surprisingly good mothers for invertebrates," Bernot said. "They carry their eggs in sacs attached to their body until the eggs hatch into swimming nauplius larvae that will molt through several larval stages and eventually go on to find their own host."

Very little is known about the life cycle and lifespan of these parasites, but they are permanent fixtures to the fish and likely live for several months as they grow from a near microscopic size, Bernot said.

"Even after the parasite dies, remnants of the embedded head can still be found in their host for many years," Bernot noted.

A CT scan of an ancient marine reptile that was entombed while pregnant has revealed a huge surprise — there were two fetuses inside her fossilized remains.

"Twins! She has another baby," Judith Pardo-Pérez, a paleontologist at the University of Magallanes in Chile who first discovered the fossil in 2009, told Live Science, adding that she plans to release more details of this discovery in a forthcoming research paper.

Sixteen ago, researchers working in southern Chile's Torres del Paine National Park struck paleontological gold, unearthing the fossilized remains of a pregnant ichthyosaur — a dolphin-like predator that patrolled the seas for most of the Mesozoic era (252 million to 66 million years ago).

The ichthyosaur was preserved in exquisite detail, and included the approximately 6-inch-long (15 centimeters) skeleton of an unborn fetus, the researchers initially reported.

The fossil was first discovered in 2009 when Pardo-Pérez was working as a doctoral student. When she returned to the site a year later, she noticed unusual bones between the ribs of the main fossil, indicating the presence of a fetus — but it wasn't until 2022 that the pregnant ichthyosaur, dubbed Fiona, was fully excavated.

Now, Pardo-Pérez and colleagues have carried out a full analysis of the fossil. Their findings were published Feb. 25 in the Journal of Vertebrate Paleontology.

Related: The world's largest ichthyosaur may have just been discovered in the Swiss Alps

The ichthyosaur, which lived approximately 131 million years ago, is estimated to have been around 11.5 feet (3.5 meters) long. Its remarkable preservation is attributed to the rapid burial of the carcass in sediment, coupled with a lack of scavengers, likely due to low oxygen levels on the seafloor, according to the study. Researchers identified it as Myobradypterygius hauthali, a species previously known from other fragmentary remains.

This find represents the third instance of a pregnant ichthyosaur from the Cretaceous period (145 million to 66 million years ago), although pregnant ichthyosaurs dating to the Jurassic and Triassic periods have also been found. The fetus' vertebrae, measuring approximately 0.6 inches (1.5 cm) in height, are surprisingly large in proportion to Fiona's 11.5-foot length. The researchers feel that M. hauthali may have given birth to relatively large babies.

Although some earlier ichthyosaurs pushed their newborns out head first, Fiona's remains suggest otherwise. The orientation of the fetus inside Fiona suggests that, like many evolutionary "advanced" ichthyosaurs, M. hauthali delivered its young tail first, an adaptation also seen in modern dolphins and whales.

The researchers also uncovered Fiona's last meal: the remains of small fishes. This is a rare glimpse into the dietary habits of Cretaceous ichthyosaurs, as direct evidence of their meals is uncommon.

Pardo-Pérez is continuing to analyze the pregnant ichthyosaur and has performed a CT scan of the fossil, allowing her to observe the entire skeleton in greater detail. It was then that she discovered that the ichthyosaur was pregnant with twins, and she plans to publish a new study on these findings in the future.

Fossils of 15 million-year-old freshwater fish discovered in Australia represent a species completely new to science — and they still have the remains of their final meals in their stomachs.

The fossils of the new species, named Ferruaspis brocksi, were unearthed by paleontologists at the McGraths Flat fossil site in New South Wales, Australia, according to a new study published March 17 in the Journal of Vertebrate Paleontology.

Inside several of the fish's stomachs were the fossilized remains of their last suppers, including bits of insect larvae, two insect wings, and a bivalve (a mollusk with two hinged shells, such as a clam or a mussel).

The discovery is the first fossil of a freshwater smelt — a small, silvery fish — in the group Osmeriformes to have been discovered in Australia and will help scientists determine when these fish arrived on the enormous island.

"The discovery of the 15 million-year-old freshwater fish fossil offers us an unprecedented opportunity to understand Australia's ancient ecosystems and the evolution of its fish species, specifically the Osmeriformes group during the Miocene epoch, 11-15 million years ago," study lead author Matthew McCurry, a paleontologist at the Australian Museum and the University of New South Wales, said in a statement.

Osmeriformes is a broad order of fish that includes various smelt species found worldwide, both in freshwater and marine environments. Smelt are relatively common across the U.S., particularly in the Great Lakes, the Northeast, the Pacific Northwest, and Alaska, though some species are also present in inland rivers and lakes. There are at least six species of smelt across the country, including rainbow smelt (Osmerus mordax), Eulachon or Columbia River smelt (Thaleichthys pacificus) and delta smelt (Hypomesus transpacificus).

Scientists have long wondered exactly when smelt and related species arrived in Australia because the fossil record for this group of fish and their ancestors has been notably sparse. "Without fossils it has been hard for us to tell exactly when the group arrived in Australia and whether they changed at all through time," McCurry said.

Related: Living fossils: 12 creatures that look the same now as they did millions of years ago

In the new study, the researchers describe how they discovered the fossilized remains of F. brocksi embedded in goethite, an iron-rich mineral. By analyzing the fossils with high-powered microscopes, the researchers discovered that the specimens had been preserved with a surprisingly high level of detail. The position of the fish's bones and fins, cells that gave the fish color, and their final meals had all remained frozen in time for 15 million years.

Because the paleontologists discovered several fish from this new species preserved at the same site, they could piece together what the ancient fish species might have looked like, as not every fish was entirely preserved. According to the researchers, F. brocksi represents an early ancestor of species in the Osmeriformes order found across Australia and New Zealand today.

"The fossils formed between 11 [million] and 16 million years ago and provide a window into the past," McCurry said. "They prove that the area was once a temperate wet rainforest and that life was rich and abundant in the Central Tablelands, NSW [New South Wales]."

Their stomach contents also offer a glimpse into the behavior of this ancient species. "We now know that they fed on a range of invertebrates, but the most common prey was small phantom midge larvae," McCurry said.

Additionally, the unexpected discovery of fossilized pigment cells called melanophores allowed the researchers to determine what color the fish might have been. "The fish was darker on its dorsal surface, lighter in colour on its belly and had two lateral stripes running along its side," study co-author Michael Frese, a researcher at the University of Canberra and Australia's national science agency CSIRO, said in the statement.

Melanophores are responsible for producing melanin, the pigment that gives color to skin, hair, eyes and feathers.

"Fossilised melanosomes have previously enabled palaeontologists to reconstruct the colour of feathers," Frese said, but melanosomes have never been used to reconstruct the color pattern of a long-extinct fish species.

Researchers collecting fossils deep inside Kentucky's Mammoth Cave have uncovered the remains of a never-before-seen species — an absolutely tiny ancient shark with nail-like teeth.

The newfound species is called Clavusodens mcginnisi, or McGinnis' nail tooth. The animal lived 340 million years ago and belonged to a group of sharks known as obruchevodid petalodonts, or "chipmunk sharks" because of their tiny size and unusual teeth.

These sharks grew to just 3 to 4 inches (7.5 to 10 centimeters) long and fed on crustaceans, worms and other prey on the seafloor, according to a statement released by the National Park Service (NPS). It's thought their tiny size helped them avoid large predators while foraging.

Researchers unveiled McGinnis' nail tooth in a study published Jan. 24 in the Journal of Paleontology. The species name is named after David McGinnis, a retired National Park Service superintendent, and their teeth, which resemble old iron nails.

Related: 325 million-year-old shark graveyard discovered deep within Mammoth Cave harbors new fossilized species

Mammoth cave

A team of researchers plucked the fossils out of rocks inside Mammoth Cave, the longest cave system in the world. Mammoth Cave is a treasure trove for ancient fish fossils, with more than 70 different species identified within its walls, according to a 2024 study published in the journal Parks Stewardship Forum.

Underground rivers and streams forged the cave's passages, which are made up of rocks that have preserved marine sediment from the Carboniferous period (358.9 million to 298.9 million years ago). The cave has given researchers a unique window inside these rocks, and therefore the marine environments they preserve, according to the 2024 study.

Researchers have been documenting vertebrate fossils in Mammoth Cave since 2019. The work is challenging because of the cave's often cramped conditions and limited space to move equipment in and out.

"Many of these sites have low ceilings requiring crawling for long distances on hands and knees, and at times belly crawling," the researchers wrote in the new study. "The fish fossils are frequently encountered in the cave ceilings or walls."

The newly discovered fossils came out of the Ste. Genevieve rock formation and date back to 330.9 million to 323.2 million years ago. The fossils are the oldest obruchevodid petalodonts discovered so far, according to the study.

Researchers suspect that these ancient sharks may have lived in reef-like systems filled with marine invertebrates called crinoids, or sea lilies, that attached themselves to the sea floor like plants. However, that assessment remains speculative until researchers carry out more studies on the ancient fish and their habitat, according to the study.

Discoveries like McGinnis' nail tooth enable researchers to learn more about long-extinct sharks and the ecosystems they inhabited.

"The fossil discoveries in Mammoth Cave continue to reveal a wealth of new information about ancient shark species," Barclay Trimble, the superintendent at Mammoth Cave National Park, said in the statement. "Researchers and volunteers collected samples from the main Mammoth Cave system and from smaller isolated caves throughout the park that have provided new data on previously known ancient sharks and revealed several species that are brand new to science."

Researchers have discovered a never-before-seen golden cave fish in southwestern China that's still evolving to survive underground.

The scaleless fish is a previously unknown species of golden-line fish (Sinocyclocheilus), which are only found in and around Chinese caves. The discovery therefore offers scientists a window into the evolution of these unusual cave-dwelling creatures.

Some golden-line fish have lost their scales and eyes as part of adaptations to cave life — there's no point having eyes if it's too dark to see anything. The newfound species, which the researchers named "Xingren golden-lined fish" (S. xingrenensis) after the city close to where it was found, has large eyes but no scales, suggesting it is still evolving to suit its conditions, according to the study, published Feb. 24 in the journal Zoosystematics and Evolution.

Previous research suggested that golden-line fish moved into caves when China was drying up — so there was less water outside — towards the end of the Miocene epoch (23 million to 5.3 million years ago) and in the Pliocene epoch (5.3 million to 2.6 million years ago). By examining the evolutionary history of golden-line fish, the study authors found that Xingren and others like it probably lost their scales during the Pleistocene (2.6 million years to 11,700 years ago), similar to when some members of the group supposedly started losing their eyes.

"This further suggests that most cave fishes may not have lived in cave ecosystems for more than a few million years," the researchers wrote in the study. "Thus, together with the eyes and scales, we hypothesize that the new species may be undergoing a gradual evolutionary process towards caves."

Related: Do fish get thirsty?

Sinocyclocheilus is the most diverse group of cave fish in the world with 80 recognized species — the Xingren golden-line fish makes 81. Researchers found this latest addition to the group while collecting golden-line fish in southwestern Guizhou province between 2012 and 2020, according to the study.

Golden-line fish are strikingly varied in appearance. The newfound species differs from known golden-line fish thanks to a unique combination of features, including having a scaleless body with irregular black markings. Xingrens also lack a horn-like structure present on some golden-line fish, notably S. longicornus, a unicorn-like blind fish discovered in 2023.

Researchers still have much to learn about Xingrens, but their eyes offer some clues about how this species lives. The researchers suggested that Xingrens' lives are linked to photoperiods, which are the lengths of daylight periods an organism receives within 24 hours. After all, Xingren eyes are significantly larger than the blind fish found in total darkness deep in caves, and can therefore still detect light.

"This is related to the habitat, where the new species can be connected to surface streams through cave windows, and their life rhythms may be closely related to photoperiods," the study authors wrote.

Researchers have tagged a giant great white shark off the East Coast of the U.S. that they say is the largest male they've ever studied in the northwest Atlantic.

The shark, which the researchers named "Contender," measured 13 feet, 9 inches (4.2 meters) long — about as long as a compact car — and weighed an estimated 1,653 pounds (750 kilograms).

Shark non-profit OCEARCH tagged the great white shark (Carcharodon carcharias) on Jan. 17, around 45 miles (70 kilometers) east of the coastline on the Georgia-Florida border. OCEARCH have since shared videos on social media of the moment Contender was caught and released.

Contender is the largest male great white shark ever caught, tagged and released by OCEARCH in the western North Atlantic region, according to the non-profit. OCEARCH researchers tag white sharks spending their winters off the southeastern United States.

Dr. Harley Newton, OCEARCH's chief veterinarian and senior veterinary scientist, told Live Science in an email that Contender was only the third adult animal they'd caught and sampled during the sharks' winter residency.

"Male white sharks mature at approximately 26 years of age and around 11.5 feet [3.5 m], so certainly we were excited to see an animal of his size at nearly 14 feet [4.3 m]," Newton said.

Related: 'Mega momma' great white shark killed on drumline may reveal secrets about iconic predator

Most shark length records are estimates, and the larger estimates are often disputed. However, mature males are 11 to 13 feet (3.4 to 4 m) long, according to the Smithsonian National Museum of Natural History in Washington, D.C. That range means Contender is about 9 inches (23 cm) longer than a typical large male of this species.

Female great white sharks grow to around 20 feet (6.1 m) long — much larger than males — so Contender is far from the biggest member of its species on record. The biggest reliably measured great white shark was 19 feet, 9 inches (6 m), according to the Massachusetts Division of Marine Fisheries. However, there are unconfirmed reports of great whites growing to around 23 feet long (7 m), according to the Florida Museum of Natural History.

Newton said that because they don't encounter adult size white sharks of either sex very frequently, Contender was an important find. OCEARCH has been trying to better understand the lives of white sharks in the North Atlantic to help inform conservation efforts to protect them.

"The elusiveness of the adult animals for researchers may simply reflect that they spend their time in deeper waters/further offshore from sites where active tagging efforts are being performed," Newton said.

The team used a smart position and temperature transmitting (SPOT) tag to monitor the animal. A SPOT tag, which is fixed to the shark's first dorsal fin, sends a signal to a satellite each time the shark breaks the surface of the water, according to the World Wildlife Fund (WWF). The tag transmits the shark's position while also recording depth and temperature data.

Contender has traveled about 290 miles (470 kilometers) since he was tagged on Jan. 17, according to OCEARCH's shark tracking website, where they describe him as "the ultimate ocean warrior." The latest ping from his tag, recorded on Monday (Feb. 10), revealed he was out at sea east of Merritt Island, near Orlando, in Florida.

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Scientists have unlocked the secret sex lives of sharks off North Carolina by examining gruesome bite wounds inflicted during the act.

Shark sex is not for the faint-hearted, requiring them to press their bellies together while the male penetrates the female. This happens swiftly for small sharks, but larger species are less nimble and struggle to hold the position, so the male often grasps the female with his teeth, leaving bloody wounds on her body in the process.

Many males don't leave unscathed either. Some females bite back during sex, according to a new study, published Dec. 4 in the journal Environmental Biology of Fishes.

By examining bite wounds in male and female sharks, researchers can pinpoint the timing and location of mating activity that remains largely hidden in the wild.

"Observations of mating for any shark or ray species are very rare so we used mating wounds as indirect evidence for reproductive behavior," study lead author Jennifer Wyffels, a researcher at Ripley's Aquariums and the University of Delaware, told Live Science in an email. "Sharks and rays use their mouths to hold and position females and therefore, mating wounds are common during the reproductive season."

Related: 'Mega momma' great white shark killed on drumline may reveal secrets about iconic predator

But detailed observations of mating wounds are scarce in the scientific literature, so researchers know little about this aspect of shark reproduction, Wyffels said.

For the study, Wyffel and colleagues examined mating wounds in sand tiger sharks (Carcharias taurus) — a critically endangered species that grows up to 10 feet (3 meters) long and inhabits coastal areas worldwide.

The researchers first observed a group of sand tiger sharks in an aquarium, where they witnessed mating activity that resulted in severe injury to a female. The deepest wound cut through the female's skin and exposed the underlying muscle, but the lesion was quick to heal, the researchers noted in the study.

Next, based on these data, the researchers established a scale from 1 to 4 to describe the severity and healing stages of shark mating wounds — with 1 describing fresh wounds, 2 and 3 describing intermediate levels of healing, and 4 describing initiation of scarring.

The team then applied this healing scale to pictures of sand tiger sharks from the database Spot A Shark U.S.A., which encourages citizen scientists to submit images of C. taurus snapped along the Northwest Atlantic coast. In total, the researchers analyzed 2,876 photographs of 686 sand tiger sharks taken between 2005 and 2020 off the coast of North Carolina.

The images revealed that coastal North Carolina is a hotspot for sand tiger shark sex.

The researchers detected an increase in stage 1 wounds in late May, marking the start of a voracious mating season in the region. The peak leveled off in July, indicating that mating is less frequent and/or less aggressive then, according to the study.

"By mid to late summer, mating has ceased based on the lack of stages 1 and 2 mating wounds on females," the researchers wrote in the study.

But females stuck around after the end of the mating season, photographs taken in late summer revealed. Many of these remaining females had stage 3 and 4 wounds, indicating that the region is both a mating habitat and a gestation habitat for pregnant females, according to the study.

The results unveil little-known aspects of shark reproduction, but they also confirm that sharks have unusually fast healing rates. Anecdotal reports have long suggested that sharks can survive extreme injuries and emerge with little to no scarring, but observations are rare. Here, the deep wounds of the aquarium female closed after just 22 days, and scarring finished 85 days post injury, the study noted.

"By combining aquarium and wild sand tiger shark wound healing observations, we were able to describe wound stages and a timeline for healing for this species," Wyffels said. "This information was used to infer the mating season for wild sand tiger sharks."

An enormous great white shark recently killed on a drumline in Queensland, Australia, will be used to help researchers discover more about the species. The gigantic female was only slightly smaller than the largest great white ever caught.

The 18.4-foot-long (5.6 meters) female white shark (Carcharodon carcharias) was found dead by the Queensland Shark Control Program at Tannum Sands, off the Queensland coast, on Aug. 10. She was pregnant with four pups when she died.

"This is the largest white shark caught in the Queensland Shark Control Program since its commencement in 1962," Tracey Scott-Holland, a spokesperson for the Queensland Department of Agriculture and Fisheries told Live Science in an email.

Reliable, verified records of large white sharks are lacking, and many historical records of behemoth sharks over 21 feet turned out to be exaggerations. The biggest white shark with a reliable measurement was caught off the coast of Massachusetts and measured 19.9 feet (6 m).

A drumline is a fishing method that uses a baited hook that's attached to a buoy and floats, with a chain anchoring it to the seafloor. The Queensland Shark Control Program uses drumlines to reduce the risk of shark bites. If a bull, tiger or great white shark — or other species associated with unprovoked bites —is caught in the Great Barrier Reef Marine Park, it is tagged, relocated and released as long as it is possible and safe to do so. Those caught outside the Marine Park are euthanized.

In Queensland, the authorities have been trialing catch alert drumlines, which send a satellite alert to a response team when a shark is caught so they can quickly tag and release the animal. But in the case of the pregnant great white shark, the team didn’t get to her in time.

"It is a shame to lose a big, reproductive animal like that," Bob Hueter, shark expert and chief scientist at OCEARCH, told Live Science in an email. "Normally, the workers are able to get out to the caught shark within a half-hour or so to tag and release the animal."

Related: 'One of the holy grails of shark science': Watch 1st ever footage of baby great white shark moments after birth

As apex predators, sharks keep the ocean's food web balanced and healthy, so a decline in their populations has a knock-on impact on many other animals. Globally, a third of sharks, rays and chimaeras are threatened with extinction.

Great white sharks are listed as vulnerable on the IUCN Red List of Threatened Species and face threats including overfishing and being caught as bycatch. The eastern Australasian population has around 750 breeding adults left.

White sharks reach sexual maturity at around 20 or 30 years old and carry between two and 17 pups every two or three years. This slow reproduction makes it difficult for the species to recover from threats.

The untimely death of a breeding female can have a significant impact on the local population. "Losing this very large, pregnant female along with her four pups is a setback for the [population's] genetic diversity and rebuilding capacity," Hueter said.

Leonardo Guida, shark conservation lead at the Australian Marine Conservation Society, told Live Science in an email that "a mixed wave of awe and sadness washed over [him]" when he heard the news.

Based on her size, "It's plausible she was born in the late 90s, when white sharks first became a protected species in Australia," he said.

But this loss could help scientists learn more about the species. "Samples were taken for research purposes, and we are collaborating with researchers from New South Wales and South Australia on several projects," Scott-Holland said. The shark's body will be used to help researchers find out more about the species' biology, genetics and populations.

Hueter — who is not involved in the analysis — is excited by what could be discovered. "Because it is exceedingly rare to be able to examine a pregnant white shark anywhere in the world, this particular shark could be very valuable for white shark science," he said.

Analyzing samples from a dead shark can provide data on the animal's feeding habits, contaminants in its waters and more.

"We're not even sure how long gestation takes in this species, and how often the females get pregnant, so examination of this 'mega momma' could help fill in some critical gaps in our knowledge," Hueter said.

A vast array of ancient fish-trapping facilities created by the direct ancestors of the Maya has been discovered in Belize.

The facilities were capable of capturing enough fish to feed up to 15,000 people a year. They consisted of a network of canals and ponds that guided fish into areas where they could be easily caught.

Hunter-gatherers constructed these complex networks about 4,000 years ago, during the Archaic period, a time before people in the region were practicing agriculture on a large scale, scientists wrote in the study, published Nov. 22 in the journal Science Advances.

"This is the earliest large-scale Archaic fish-trapping facility recorded in ancient Mesoamerica," the team wrote in the paper. The success of these hunter-gatherers appears to have helped lead to the formation of the Maya, a civilization that later came to dominate the Maya Lowlands in Central America and modern-day southern Mexico.

These fish-trapping facilities would have encouraged people to gather and develop permanent settlements and, later, cities. "It seems likely that the canals allowed for annual fish harvests and social gatherings, which would have encouraged people to return to this area year after year and congregate for longer periods of time," study co-author Marieka Brouwer Burg, professor of anthropology at the University of Vermont who is co-director of the team, said in a statement.

"Such intensive investments in the landscape may have led ultimately to the development of the complex society characteristic of the pre-Columbian Maya civilization, which subsequently occurred in this area by around 1200 [B.C.]," Brouwer Burg said.

Related: Lasers reveal Maya city, including thousands of structures, hidden in Mexico

At the time the fish-trapping facilities were built, the region was becoming drier and people may have been dealing with droughts, the team wrote in the study. This may have encouraged people to come together and build the facilities to ensure they had enough to eat.

The team used satellite images and aerial images taken by drones to detect the canals and ponds. They also conducted excavations and radiocarbon dated organic sediments and charcoal to determine when the fish trapping facilities were built.

The Maya continued to use these fishing facilities in Formative times (circa 2000 B.C. to A.D. 200), the researchers wrote in the study.

"Honestly, this discovery is stunning," Thomas Guderjan, an anthropology professor at the University of Texas at Tyler, told Live Science in an email. "We have always thought of large-scale land modification projects as being something that occurred in the Maya classic period," or roughly A.D. 250 to 900, Guderjan said.

The research may encourage scholars to reconsider what the Maya were like around 4,000 years ago, Guderjan, who was not involved in the study, added.

Nicholas Dunning, a geography professor at the University of Cincinnati who has studied the Maya extensively, also praised the research.

"Over the past several decades, quite a few scholars of the ancient Maya, including myself, have suggested that aquaculture may have played an important role in the development of Maya civilization," Dunning told Live Science in an email. "However, the present study is the first that I know of to specifically attempt to test this hypothesis." The study "is an important work in helping scholars of the ancient Maya understand the origins of sedentary society in the region," he added.

Live Science contacted the research team but has not heard back at time of publication. In their paper, the scientists said they plan to continue their research in the region.

Sharks are some of Earth's ultimate survivors. They are among the oldest creatures on the planet, predating dinosaurs and trees and surviving multiple mass extinctions. They're also hugely diverse, with more than 500 modern species swimming the world's oceans, from little fish the size of your hand up to 60 foot (18 meters) giants.

Sharks play a critical role in ocean ecosystems, and they're found in all of Earth's oceans. But many species are now under threat from climate change, overfishing, pollution and the shark fin trade.

How much do you know about these incredible creatures? Take our science quiz to find out.

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A ghostly white deep-sea shark has been discovered off the coast of Albania.

The critically endangered angular roughshark (Oxynotus centrina) was caught by a commercial trawler off Sazan Island — an uninhabited military island — at a depth of around 656 feet (200 meters).

The shark is the first of its species to be discovered with leucism, a genetic disorder that disrupts melanin production, causing a reduction in pigmentation, scientists report in a new study. Unlike albinism, in which animals completely lack melanin and have red irises, leucistic sharks have normal iris pigmentation even if they appear completely white.

With leucism, "An individual can still produce melanin but lacks it in certain regions or [the] entire body," lead author Andrej Gajić, director of the Sharklab ADRIA in Albania, told Live Science via email. This shark was leucistic, rather than albino, because it "was notably pale with almost whitish patches on the tail, but the eyes showed normal retinal pigmentation," Gajić said. The study, published Oct. 16 in the Journal of Fish Biology, is the first description of leucism in angular rough sharks and the first record of a pigment disorder in the family Oxynotidae.

Related: Pinky-white leucistic alligator with blue eyes born in Florida is 1 of only 8 in the world

Angular rough sharks are usually dark gray-brown or black all over, with dark blotches on their head and sides to help them blend into their environment. Images show this individual was pale with whitish-gray patches. Its physical health seemed otherwise unaffected by its strange coloration.

"Some research suggests that a lack of pigmentation may make individuals more visible to both predators and prey, potentially reducing their chances of survival," Gajić said. This discovery, along with other records of healthy sharks with pigment disorders, implies that these anomalies don't have a significant negative impact on deep-sea sharks' ability to feed, avoid predators or reproduce, he added.

Pigment disorders are "exceptionally rare" among sharks, and only 15 cases have ever been documented among deep-sea species, Gajić said. He explained that leucism is primarily a genetic disorder and may be caused by abnormalities affecting the production or distribution of melanin.

"Disruptions during embryonic development can also lead to abnormal pigmentation patterns," he said. While more research is needed, other causes for changes in coloration could also include exposure to pollutants, elevated temperatures, hormonal shifts during development, and inbreeding within isolated populations.

The scientists also want to explore how human threats, such as pollution and fishing, affect sharks' susceptibility to disease and other disorders.

Vlorë, the region where the shark was caught, could be an important hotspot for sharks and rays. Other critically endangered species are found in this area, including little gulper sharks (Centrophorus uyato) and spiny butterfly rays (Gymnura altavela). "Some of these, such as spiny butterfly rays, have not been previously recorded in the Adriatic Sea in this century," he said.

What do the ginkgo (a tree), the nautilus (a mollusc) and the coelacanth (a fish) all have in common?

They don't look alike, and they aren't biologically related, but part of their evolutionary history bears a striking resemblance: these organisms are referred to as "living fossils". In other words, they appear to have escaped the transformations that normally come about over time, through evolution.

For the past 85 years, the coelacanth has been dubbed a "living fossil" because it evokes a bygone era, the age of dinosaurs. These fish belong to the sarcopterygians, a group that also includes lungfish (fish with lungs) and tetrapods, a group to which humans also belong. Tetrapods are vertebrates (animals with a backbone) that share specific anatomical features, including the presence of a humerus (forelimb bones), a femur (hindlimb bones) and lungs.

Related: This 'ancient' monster fish may live for 100 years

Few vertebrate species spark as much curiosity as the coelacanth, as much for the fascinating story of its discovery as for its status as a "living fossil." What's more, the only two living species of coelacanth, survivors of this long evolutionary process, are now threatened with extinction.

But does the coelacanth really deserve this label? And what do coelacanth fossils tell us about this evolutionary curiosity?

Respectively a paleontologist, evolutionary biologist and ecological modeller, we are taking a fresh look at the 410 million-year evolutionary history of coelacanths in this article. Using the latest technological advances and innovative analysis methods available, we are working to better understand the evolution of these fascinating species, often referred to as "living fossils".

A major discovery in Western Australia

Our research, recently published in the journal Nature Communications, identifies and describes the fossils of a 380-million-year-old extinct species of coelacanth that was discovered in Western Australia.

These remarkably well-preserved fossils come from a key transitional period in the long evolutionary history of this fish species.

This study is the result of an international collaboration between researchers affiliated with institutions in Canada, Australia, Germany, the UK and Thailand.

"Living fossils": A concept under debate

Charles Darwin was the first to use the expression "living fossil" in his book The Origin of Species, in 1859, to designate living species he considered "aberrant" or "abnormal" with respect to others at the time.

Although the concept was not clearly defined at Darwin's time, it has been taken up by hundreds of biologists since then. However, the term "living fossil" and the species that deserve the title, remains a subject of debate in the scientific community.

In general, for a taxon (a scientifically classified group or entity) to be considered a "living fossil," it must meet certain criteria: it must belong to a group that has existed for millions of years, have changed little morphologically over time, and present so-called primitive characteristics compared to its close evolutionary relatives.

A fascinating history: Coelacanths through the ages

More than 175 species of fossil coelacanth lived between the Lower Devonian period (419 to 411 million years ago) and the end of the Cretaceous period (66 million years ago). In 1844, Swiss paleontologist Louis Agassiz identified a particular group of fossil fish, which he named the order of coelacanths.

For almost a century, coelacanths were thought to have become extinct at the end of the Cretaceous period, around 66 million years ago. During this time nearly 75 per cent of life on Earth became extinct, including the majority of dinosaurs — with the exception of the ancestor of birds.

Then, on Dec. 22, 1938, Marjorie Courtenay-Latimer, the curator of the East London Museum in South Africa, received a call from a fisherman who had caught a rare and strange fish. She realized it was an unknown species and contacted South African ichthyologist (fish biologist) J.L.B. Smith, who confirmed that it was, in fact, the first living coelacanth ever observed.

In 1939, Smith named the species Latimeria chalumnae, also known as gombessa. Since then, this species, found along the east coast of Africa near the Comoros Archipelago, in the Strait of Mozambique, and off the coast of South Africa, has attracted considerable scientific interest.

In 1998, a second living species of coelacanth, Latimeria menadoensis (named ikan raja laut, the king fish of the sea, in Indonesian), was discovered off the island of Sulawesi, in Indonesia.

These two species are the only survivors of an ancient lineage that appears to have evolved little over the last few million years.

Following the discovery of Latimeria chalumnae, coelacanths were considered vertebrates whose body shape has changed little over time, suggesting slow evolution.

Ngamugawi or "ancient fish"

In our study, we describe a new species of coelacanth from the Devonian period of Western Australia. We have named it Ngamugawi wirngarri. Ngamugawi means "ancient fish" in Gooniyandi, the language of the Australian aboriginal people of the Kimberley region. Wirngarri pays homage to Wirngarri, a respected ancestor of the Gooniyandi.

Ngamugawi wirngarri was discovered in the Gogo geological formation, world-renowned as an exceptional fossil site. Gogo is famous for the three-dimensional preservation of numerous fish fossils, and sometimes even soft tissues such as the heart and muscles.

To date, over 50 species of fossil fish have been identified at Gogo. This diverse group of fish, coupled with that of marine invertebrates, cohabited in a Devonian warm sea coral reef around 380 million years ago.

A more complex evolution than it seems

Our study reveals that coelacanths evolved rapidly at the beginning of their history, during the Devonian period, but that this evolution slowed down after that. Evolutionary innovations almost ceased after the Cretaceous period, suggesting that for some traits, coelacanths, like Latimeria, appear to be frozen in time.

However, other features, such as body proportions, continued to evolve at a normal rate during the Mesozoic period (252 to 66 million years ago). Although body shape changed little, supporting the idea that Latimeria is a "living fossil," the evolution of cranial bone shape never ceased, which calls the label into question.

Of all the environmental variables studied, tectonic plate activity has the most marked influence on coelacanth evolutionary rates. New coelacanth species were more likely to emerge during periods of intense tectonic activity when new habitats were created or fragmented.

The Ngamugawi discovery shows that coelacanths have not remained unchanged for millions of years.

Their slow evolution shows that they are not "living fossils," but, in fact, the result of a complex evolutionary history.

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

Name: Northern sea robin (Prionotus carolinus)

Where it lives: The shallow waters of the western Atlantic, from Nova Scotia to Florida

What it eats: Shrimp, crabs, squid, worms and small fish

Why it's awesome: Northern sea robins are weird fish with big, spiny heads; bright-blue eyes; two giant wing fins; and six crab-like legs.

It's these little legs that make sea robins so unusual. Other sea creatures follow these fish around because they are so good at finding and digging up buried food — but until recently, scientists didn't understand what made northern robin fish such skilled foragers.

In two studies published in 2024, researchers revealed that northern sea robins' legs act like tongues, allowing the fish to taste their surroundings for signs of food.

"This is a fish that grew legs using the same genes that contribute to the development of our limbs and then repurposed these legs to find prey using the same genes our tongues use to taste food — pretty wild," study author Nicholas Bellono, a professor of molecular and cellular biology at Harvard University, said in a statement.

The scientists found that northern sea robins can detect and uncover ground-up mussels using papillae that cover their legs. Papillae are small sensory structures, which in humans are found on the upper surface of the tongue. The researchers discovered that northern sea robin papillae have taste receptors and touch-sensitive neurons, enabling the fish to use their legs to taste the ground to find food.

In one of the studies, the researchers grew northern sea robins from embryos in a lab to watch their legs develop. They found that the legs grew from the pectoral fins, separating from the rest of the fin rays during development. The legs are controlled by distinct walking muscles at the base of the legs and are shaped like shovels to help the fish dig.

Although all sea robin species have legs, not all are adapted for digging and tasting, the team found. "We were surprised to see how much sea robins differ from each other in sensory structures found on the legs," study co-author David Kingsley, a developmental biologist at Stanford University, said in the statement. "The system thus displays multiple levels of evolutionary innovation from differences between sea robins and most other fish, differences between sea robin species, and differences in everything from structure and sensory organs to behavior."

But northern sea robins' tongue legs don't always lead to a meal. After the northern sea robins dig up their dinner, the fish following them often swoop in and steal their food, in an act known as kleptoparasitism.

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.

Name: Alligator gar (Atractosteus spatula)

Where it lives: Rivers, reservoirs and coastal bays in southwestern U.S. states, down to Veracruz, Mexico

What it eats: Crabs, fish, birds, mammals, turtles, and carrion

Why it's awesome: With their long snout, thick armored scales, and two rows of piercing teeth, these huge fish could easily be mistaken for a ferocious gator — hence their common name: alligator gar.

They are the largest known species of gar and can grow to around 8 feet (2.4 meters).

Related: 'True rarity': Gigantic alligator gar caught and released in Texas reservoir could break 2 world records

This enormous fish is "a truly prehistoric monster," said biologist Jeremy Wade on "River Monsters." Fossils have shown that these ancient animals existed 100 million years ago during the Cretaceous period (145 million to 66 million years ago), when dinosaurs roamed Earth.

"Their survival is in part because of their unique defense system — scales made of a super hard enamel called ganoine," said Wade. "This armor plating has seen them survive predatory dinosaurs." These hard, interlocking flexible scales protect them from threats. Once gars are more than a meter long, their only predator is the alligator.

And alligator gars grow fast. They start as tiny toxic eggs but reach up to 2 feet (0.6 m) long in their first year. They keep growing their entire lives, and can live to 100 years old, Solomon David, an aquatic ecologist at the University of Minnesota, previously told Live Science.

Alligator gars are also among the ultimate "living fossils" — species that have barely changed for millions of years. A 2024 study found gars have the slowest rates of evolution of all jawed vertebrates. They have evolved so slowly that alligator gars and longnose gars (Lepisosteus osseus) — two species separated by 100 million years of evolution — can still produce fertile hybrid offspring. Evolution across such a long period of time typically produces wildly divergent species that could never reproduce.

By contrast, that's about the same amount of evolutionary time that separates wombats and people, two wildly different species that could never reproduce, study author Chase Brownstein, a first year graduate student at Yale, previously told Live Science.

Although their needle-sharp teeth are capable of causing a nasty bite, these ambush predators prefer eating crabs, fish, and birds. Yet, in the 1930s, the Texas Game Fish Commission created a "gar destroyer" to try to electrocute the fish by shooting 200-volts into the water. Today, the fish is protected in Florida and fishing caps are in place in Texas.

Sharks are some of the most successful, fierce and mysterious predators our world has ever known. With a history spanning around half a billion years, the shark bloodline has produced the mighty megalodon; the bizarre, buzz-saw-jawed Helicoprion; and the fearsome great white shark. So how have they done it?

John Long, a paleontology professor at Flinders University in Australia, has been researching ancient sharks and other fossilized fish for more than 40 years. In his latest book, "The Secret History of Sharks" (Ballantine Books, 2024), Long tells the incredible story of shark evolution. He spoke to Live Science about what he's learned.

Patrick Pester: Sharks have been around for about half a billion years. How have they survived so long?

John Long: They've been resourceful and adaptive. They're the only group of backboned, jawed creatures on the planet to have survived all five major mass extinction events. And it's not a matter of them saying, "Oh, there's a massive extinction event coming; I'll have to whip up some new adaptation." It's that at any time these mass extinction events struck, there was enough variety in sharks that at least some lineages of them got through.

As they developed a superior body plan, which they did by the Devonian period [419 million to 359 million years ago], sharks then looked a lot like sharks today. That body plan allowed them to diversify a lot more rapidly, so each mass extinction event had less and less of an effect on them from that point on.

They also started diversifying in the Devonian period to develop crushing types of tooth plates, as well as sharp, piercing, tearing and slicing teeth. They even developed filter feeding well before any other vertebrates. So they've always had this ability to be very plastic with their dental development, creating new tooth types and new tooth tissues. That's been one of their biggest saving graces, almost like a Swiss Army knife kind of dentition, of adaption, that they could adapt to any sort of food resource that was around.

Related: A really big shark got gobbled up by another, massive shark in 1st known case of its kind

PP: We don't want to give too much away, but can you share something you uncovered as part of this book that researchers didn't know before?

JL: Absolutely. A lot of the research I treated as investigative journalism with my background in fish evolution and shark evolution. I've published several papers describing new species of sharks, and I've dug them up myself — so I have that experience. I was able to contact all of my colleagues who are experts in all the different fields of shark evolution and interview them. Gradually, a lot of them opened up and shared with me research in press that hadn't even gone to print when I wrote the book. Now, a lot of those papers have come out, but I was able to muse on that and build it into the book well before it was public knowledge.

I got all the new information about megalodon [Otodus megalodon], the greatest predator that ever lived. They're just amazing. A lot of the new research that was just recently published was about the fact that it was warm-blooded. Researchers proved its body temperature through clumped isotope paleothermometry, which is measuring the temperature that the [isotope] bonds form at when the cartilage is forming. They can look at living sharks and get that temperature range, then apply the same geochemistry to fossils and get an accurate range of what the body temperature was. Now we know that megalodon had a body temperature of about 27 degrees Celsius [80 degrees Fahrenheit].

PP: What does that mean for the shark if it's warm-blooded?

JL: It means that it can go places other sharks can't go. It can go into colder waters — further south or further north. We've got remains of megalodon teeth from all around the globe — everywhere except Antarctica. There are Pliocene [5.3 million to 2.6 million years ago] fossil sites in Antarctica that are from the age when megalodon was still around and in its prime, and those sites have whale fossils but no megalodon teeth at all. I put this together and think that maybe whales started migrating down to Antarctica as a way of escaping from megalodons and having a safe sanctuary to feed and then came back to the warmer waters to give birth.

PP: There are still some gaps in the shark fossil record. What do you think is the biggest open question in shark evolution research?

JL: For the first 56 million years of shark evolution, we've got very little [fossil evidence]. We've only got some scales to start with in the Ordovician period [485 million to 444 million years ago]. It's not until the Devonian period, around 419 million years ago, that we start getting shark teeth in abundance in the fossil record and we find the first complete fossil sharks. That's when our knowledge of sharks really picks up.

The big question is, what is the relationship between sharks and placoderms like Dunkleosteus, these armored fishes that ruled the roost in the Silurian and Devonian periods [444 million to 359 million years ago] and went extinct at the end of the Devonian, when sharks really blossomed?

A new discovery out of China from the early Silurian is a fish called Shenacanthus, which is shark-like, having shark-like dorsal fin spines, but it's got armored plates around the head, like the placoderms. We don't have the jaws, so we don't have the teeth — we don't know if it even had teeth — but it could be a good example of these really early sharks that we only know from scales and fin spines.

There are all these mysteries: Did placoderms give rise to sharks by losing armor, or did sharks gain armor and become placoderms?

PP: A study earlier this year estimated that humans now kill up to 80 million sharks a year. You've described sharks as nature's great survivors, but can they survive us?

JL: That's the ultimate question I pose in the book. And what can we learn from sharks as ultimate survivors? In the book, I use a conservative figure and say between 70 [million] and 100 million sharks a year are killed through the shark finning industry alone, and it's terrible. It's a horrible way for the sharks to die. They just cut the fins off and throw the living shark back in the water to die a slow, painful death.

Some countries, like the U.K., are banning shark finning and the import of shark fin products. Other countries need to follow. That's the only way we can stop it. In Asian countries like China, where shark fin soup was the delicacy of the ancient dynasties, people are becoming more environmentally aware and starting to turn away from these old traditions that actually are decimating the planet.

My hope is that more information and more education to the public about this horrible practice will see people just refuse to support shark fin soup sellers. I certainly won't go to any restaurant if I know that's on the menu. I also hope countries will collaborate in terms of enforcing legislation.

PP: Do you think your book will help with rehabilitating the public image of sharks by giving a more three-dimensional view of what they are, as opposed to just mindless killers?

JL: Exactly. Ever since "Jaws," we're all terrified to go in the water — myself included. But they're beautiful things. I was invited to go on a shark tour to see the great whites [Carcharodon carcharias] myself off the Neptune Islands of South Australia — the same area where they filmed the live scenes for "Jaws." I was at first a bit apprehensive and a bit terrified. But I eventually got in the shark cage, and I started seeing this beautiful, big white shark swimming around. She was not the least bit interested in me, just focused on the tuna bait they were throwing out.

I spent a total of seven or eight hours over the course of three days there, watching maybe half a dozen different white sharks. I was amazed at how individual they all were, the individual personalities, the individual battle scars and wounds that they all bore. They've each got a life story, and each one deserves a chance at life as much as we do.

This interview has been condensed and edited for clarity.

A hungry whale mid-gulp, a lazy seagull riding a sea turtle, an adorable-yet-deadly mini octopus and a group of alien-looking fish babies fused to eggs were some of the stars of a recent ocean photography competition.

The stunning images were among those short-listed at the 2024 Ocean Photographer of the Year awards. The winners of the competition, which is run by Oceanographic Magazine and sponsored by the Swiss watch company Blancpain, were announced Thursday (Sept. 12) at an event in London's Somerset House.

In total, more than 80 photos were short-listed across 10 categories, and you can see the best ones below.

Related: Under the sea: 50 breathtaking images from our oceans

The standout image was a high-definition shot of a Bryde's whale (Balaenoptera edeni) about to gulp down a massive "bait ball" of fish. Photographer Rafael Fernández Caballero captured the stunning shot in Baja California, Mexico, and took home first place in the Ocean Photographer of the Year category.

"A feeding frenzy is the biggest show on earth for me," Fernández Caballero said in a statement. "The highlight was this whale coming out of nowhere with its mouth wide open." But there was a wide range of other species involved in the banquet, which was likely caused by the recent El Niño event, they added.

One of the standout images short-listed in the Fine Art category was a shot from Enric Gener showing a lone seagull casually sitting on a turtle's shell floating in the middle of the Mediterranean Sea.

After five hours of scanning the empty ocean for something to photograph, Gener spotted a seagull with its legs out of the water and was shocked when he realized it was standing on a sea turtle.

"I decided to jump into the water, thinking I would find the turtle dead because it wasn't moving," Gener said in a statement. "When I got close enough, I saw its face underwater and realised that the sea turtle was alive."

The runner-up in the Ocean Portfolio category was Katherine Lu, who captured a peculiar deep-sea scene in the Philippines. It shows a juvenile poison ocellate octopus (Amphioctopus mototi) planted on a pyrosome, a free-floating colonial creature made up of single-cell tunicates embedded in a gelatinous "tunic."

"Each night during the vertical migration, deep-sea creatures like this octopus migrate upwards to the lighter, shallower waters to feed and avoid predators before descending back into the depths by morning," Lu said in a statement. But hitching a ride on the pyrosome makes this daily migration much easier, she added.

The tiny octopus, which was around 0.8 inch (2 centimeters) tall, contains the same toxin as blue-ringed octopuses (Hapalochlaena), which are among the deadliest animals on Earth.

First place in the Ocean Portfolio category went to Shane Gross, who photographed a bizarre litter of baby plainfin midshipman fish (Porichthys notatus) off the coast of British Columbia, Canada. The wide-eyed juveniles sat atop glowing orange yolk sacs, which they were still attached to at the time.

The vulnerable younglings remain tied to their eggs and "are guarded over by their father until they are big enough to swim out from under the rock they are living on," Gross explained in a statement. Once they leave their den, the fish will swim off into the deep sea and won't return to the shallows until it is their turn to breed, Gross added.

In the Wildlife Photographer of the Year category, Gross was also short-listed for an eye-catching image of a peppered moray eel (Gymnothorax pictus) lying slumped over rocks between two intertidal pools on D'Arros Island in the Seychelles.

A pair of smaller eels can also be seen slithering out of water in the foreground. "Their ability to come completely out of the water is amazing and surprising," Gross said.

You can check out more of the amazing images below.

Name: Angular roughshark (Oxynotus centrina)

Where it lives: In the eastern Atlantic ocean from Norway to South Africa, and the Mediterranean sea

What it eats: Fish, crustaceans, molluscs, marine worms and shark eggs

Why it's awesome: When we think of sharks, we tend to imagine large, muscular predators like great whites or hammerheads. But for the pig-like angular roughshark, this is not the case. These bizarre sharks have flat heads, wide-set eyes and pink snouts.

"It is commonly called a 'pig fish' because when it comes out of the water it emits a kind of grunt," Yuri Tiberto of the Elba Aquarium in Italy, told Toscana Media News in 2021, after a dead individual was pulled from the water in Elba, an Italian island near Tuscany, and posted to Facebook by the tourism website Isola d'Elba App.

Angular roughsharks generally grow around 3.3 feet (1 meters) long and have thick, gray-brown bodies with two large dorsal fins that resemble sails. They have a triangular profile from the front.

Like all sharks, their skin is covered in dermal denticles — flat, V-shaped tooth-like structures that consist of pulp, dentine and enamel.

While all sharks have denticles, roughshark denticles are particularly large and pronounced, giving them a fuzzy appearance. Scientists don't know exactly why this is, but it may be to help protect the animal from larger predators.

Combined with its furry-looking face, the angular roughshark also has a short, blunt snout with massive nostrils, adding to their pig-like appearance.

These strange features relate to their lifestyles; they spend most of their time swimming just above the seafloor looking for food. They tend to move slowly, vacuuming up their prey.

They have one set of sharp, blade-like lower teeth to slice through flesh, as well as conical upper teeth which help to spear slippery prey.

Recent research suggests angular roughsharks also feed on the eggs of other sharks. As well as discovering shark embryos in the stomachs of wild roughsharks, in 2015 scientists reported a captive angular roughshark that fed exclusively on the eggs of elasmobranches.

Although these sharks have little commercial value, their large dorsal fins and spines make them susceptible to being caught in nets as bycatch by fishers .They are also listed as endangered on the International Union for Conservation of Nature Red List of Threatened Species.

Primeval fish that were thought to be "living fossils," largely unchanged since the time of the dinosaurs, are actually evolving dramatically — and they evolved faster when Earth's continents moved faster, fossils of a newly identified coelacanth species have revealed.

The findings suggest that the large-scale movement of continents may spur the evolution of life, the researchers reported Thursday (Sept. 12) in the journal Nature Communications.

Coelacanths are large fish that evolved 410 million years ago. Once known only from fossils, they were thought to be extinct until a fisher in South Africa hauled one up in 1938. Biologists dubbed the modern coelacanth a "living fossil" and believed it had not evolved much over millions of years.

The two coelacanth species alive today, Latimeria chalumnae and Latimeria menadoensis, are more closely related to other early fish, such as lungfish, than they are to today's modern ray-finned fish.

Related: How fast does evolution happen?

But now, new "bridge" fossils reveal that coelacanths never stopped changing. The fossils, beautifully preserved in three dimensions, are one of the best anatomical looks yet at coelacanth history. Combined with other coelacanth fossils, the discovery reveals that the more geologically active the environment was, the more evolutionary change the fish underwent.

"Somewhat surprisingly, plate tectonic activity had a strong influence on rates of evolution of coelacanths throughout their 400 million-year history," said study first author Alice Clement, an evolutionary biologist at Flinders University in Australia.

The newly identified species of coelacanth, Ngamugawi wirngarri, was found in the Kimberley region of northwestern Australia. It's now tropical, with landscapes ranging from mountains to grasslands. But 385 million years ago, it was a thriving reef with at least 50 species of fish, Clement told Live Science. "In a sense, it was Australia's first great barrier reef, stretching hundreds of kilometers offshore," she said.

Two specimens of the new coelacanth species were first found in 2008. It was the first coelacanth from the site, Clement said, so researchers knew they had something special. But it took years to prepare the fossils and analyze the finds.

The newly identified species' scientific name means "ancient fish" in the language of the First Nations Gooniyandi people, who live near the fossil beds. The species was small — only about 7.8 inches (20 centimeters) long. The modern species, by contrast, are about 6.5 feet (2 m) long.

The anatomy of the fish fell between the earliest "primitive" species, which date to 410 million years ago, and the species that still swim the oceans today. By looking at differences among the fossils over time, the researchers learned that while the fish's large-scale features, like its body shape, have stayed consistent since the Cretaceaous more than 66 million years ago, the bones of the jaw and skull have continued to evolve.

In fact, study co-author Richard Cloutier, an evolutionary biologist at the University of Quebec at Rimouski, told Live Science that if all researchers had to go on was the skull, "we would have never thought that it was a 'living fossil,' because it changed so much."

The change was associated with faster rates of continental drift, even more so than environmental factors such as oxygen levels in the ocean or water temperatures, the researchers found.

"I suppose," Clement said, "that greater tectonic plate activity drives the formation of new environments, or splits existing populations in half to continue upon their own natural evolutionary experiments."

Japanese eels have found an ingenious way to escape a fish's stomach after being swallowed — backing up the digestive tract then squeezing themselves out of the predator's gills.

In a scientific first, researchers in Japan have used X-ray videography to capture the behavior of live prey inside its predator's digestive tract.

The dark sleeper fish (Odontobutis obscura) swallows its prey whole and alive. The team discovered that juvenile Japanese eels (Anguilla japonica) wolfed down by the fish can insert the tip of their tails through the fish's esophagus and gill, then wriggle it out of the gill, pulling themselves backward until they're entirely free. The researchers published their findings Monday (Sept. 9) in the journal Current Biology.

In previous work, the authors had noticed that juvenile eels can escape through their predator's gills — but they didn't know exactly how. "Before the X-ray video experiment, we hypothesized that eels might escape directly from the predator's mouth through the gills," co-author Yuuki Kawabata, an associate professor in the Graduate School of Fisheries and Environmental Sciences at Nagasaki University, told Live Science in an email.

When the scientists saw the tiny eels wriggle toward the gills from the predator's stomach — rather than escaping through its mouth — they were "absolutely astonished," Kawabata said. "We were anticipating more straightforward escape routes, but their ability to navigate back up the digestive tract was truly surprising," he said.

Related: Alien-like photo shows eel dangling out of heron's stomach in midair

It took the team a year to film compelling evidence showing how the eels were pulling off their great escape.

The researchers injected the eels with the contrast agent barium sulfate so they could see it inside the stomach of the dark sleeper fish once it had been eaten. Then, they put an eel in a tank with a fish and recorded the interaction using X-ray video.

Of the 32 eels that were swallowed whole by the fish and reached its stomach, 13 managed to push their tail out of the fish's gill and nine made a successful escape.

Not all the eels used the same tactic to try to find freedom. Eleven individuals that had been swallowed entirely tried swimming in circles along the stomach wall, with the researchers wondering if they were looking for a way out. Five of these managed to get their tail into the fish's gills.

The fish weren't significantly harmed by the eels escaping through their gills. "The eels are small and slippery, and the process did not cause any lasting damage to the predatory fish," Kawabata said. "After each experiment, the fish continued to behave normally."

Even though these observations were made in a controlled lab setting, the researchers suspect that it also happens in the wild. "Given the frequency with which it occurred in our experiments, it is possible that this behavior could be more common in natural environments, especially when eels are faced with similar predatory threats," he said.

Next, the team wants to find out if other eel species escape in the same way. They also want to know why some individuals are better escape artists than others. "One of our main outstanding questions is whether this behavior is unique to Japanese eels," he said. "We are also curious about the specific physiological traits, such as muscle strength and behavior, that make some eels more successful at escaping than others."

Name: Giant oarfish (Regalecus glesne)

Where it lives: In the mesopelagic zone of the Mediterranean Sea, Atlantic and Pacific Oceans

What it eats: Krill, plankton, crustaceans and squid

Why it's awesome: According to Japanese myth, oarfish are harbingers of earthquakes, and their appearance signals a tremor could be about to hit.

In traditional Japanese legend, oarfish were known as "ryugu no tsukai" meaning "the messenger from the sea dragon god's palace." People believed oarfish would come up from the deep to warn people when an earthquake was imminent. This myth caused a stir in 2011 when 20 oarfish washed ashore in the months before Japan was struck by the country's most powerful earthquake.

While there is no evidence to back up the link between oarfish sightings and earthquakes, in August 2024 snorkelers found an oarfish in California — two days before an earthquake hit the region. However, scientists believe this was a coincidence.

Related: New piranha-like fish with 'human teeth' and Eye of Sauron marking found deep within the Amazon

Also known as the king of herrings or ribbonfish, the oarfish is the world's longest bony fish. The species' elongated body is usually around 10 feet (3 meters) long, but individuals can grow to 36 feet (11m) — around twice as long as a giraffe is tall.

"The striking nature of this long, sinewy fish is what many people say gave rise to the original notion of sea serpents," Russ Vetter, a biologist at National Oceanic and Atmospheric Administration's Southwest Fisheries Science Center, said on the podcast On The Line. "From beginning to end, this has all the qualities you would want in a sea serpent."

Oarfish don't have any visible teeth and instead filter water to eat tiny prey. "You could put your hand into the mouth, around the mouth, down the throat and not even scratch your skin," Vetter said.

These unusual creatures live in the mesopelagic zone of the deep sea where there is no light — one reason we know so little about them and why sightings are so rare. They usually live around 650 feet (200 m) below the surface but can be found as deep as 3,300 feet (1,000 m).

Like other animals in this zone, oarfish swim to the surface at night to find food before returning to the safety of the deep during the daytime. In the rare instances that oarfish are seen in shallow waters, they are usually sick, dying or were caught in strong currents.

A large, predatory shark swimming near Bermuda was gobbled up by an even bigger shark — even swallowing the tracking device that was attached to it — in what scientists say is the first recorded case of its kind.

Porbeagle sharks (Lamna nasus) can grow to about 12 feet (3.6 meters) long. These large sharks patrol the Northern Atlantic Ocean as well as parts of the oceans of the Southern Hemisphere, ranging into the Antarctic. Their muscular, streamlined forms and angled, spear-like teeth make them formidable predators. But the porbeagle, it seems, is not immune to predation itself.

In a paper published Tuesday (Sept. 3) in the journal Frontiers in Marine Science, researchers describe the likely predation of a porbeagle shark by one of its larger relatives. "This is the first documented predation event of a porbeagle shark anywhere in the world," study lead author Brooke Anderson, marine fisheries biologist with the North Carolina Department of Environmental Quality said in a statement.

The pregnant female shark was tagged in October 2020 using both a satellite transmitter and a pop-off satellite archival tag (PSAT) near Cape Cod. Data from these devices was meant to track the shark's depth and geographic range over time. While satellite transmitters are permanent, the PSAT tags are designed to detach from the animal after a year, having recorded data on its movements.

Related: Great white sharks split into 3 populations 200,000 years ago and never mixed again — except for one hybrid found in the Bermuda Triangle

The porbeagles follow their prey, changing position in the water column throughout the day.

Their depth is calculated using pressure and temperature data from the PSAT tags. Anomalies in pressure and temperature indicate that the animal has died, or the tag has somehow detached prematurely.

In this case, the shark ranged between the surface and 328 feet (100 m) down until December 2020, when it began diving to depths of up to 2,600 feet (800 m) during the day and hovering around 650 feet (200 m) at night. It maintained that pattern as it moved south from where it was tagged to waters off the shore of Bermuda.

On March 24, 2021, the temperature patterns that correlated to its recorded depth changed drastically. While the shark had previously been moving through waters that ranged from 43.5 to 74.3 degrees Fahrenheit to –(6.4 to 23.52 degrees Celsius), on that day the tag recorded temperatures between 61.5 to F76.5 F (16.4 C to 24.72 C) despite remaining at a similar depth range.

The researchers believe this shift meant the tag was inside the stomach of another shark at the time as temperatures were warmer than they would have otherwise been at those depths.

Based on the geographical ranges of sharks large enough to eat a porbeagle, the predator was likely either a white shark (Carcharodon carcharias) or a shortfin mako (Isurus oxyrhinchus), the authors said. A white shark seems more likely given the more stable depth range of the tag while it was ingested — makos tend to make deeper dives and then rapidly ascend.

The team said the finding has implications for the porbeagle population — a species already under threat from historic overfishing. It is listed as vulnerable by the IUCN. "The predation of one of our pregnant porbeagles was an unexpected discovery," Anderson said. "We often think of large sharks as being apex predators. But with technological advancements, we have started to discover that large predator interactions could be even more complex than previously thought."

Striking new satellite imagery shows a Canadian river quickly swelling in size after a massive landslide completely dammed the waterway. The obstruction may have also doomed an endangered salmon population by preventing the individuals that survived the sudden damming from reaching their spawning grounds upriver.

The massive landslide occurred late on July 30 near Farwell Canyon on the southern bank of the Chilcotin River — a 150-mile-long (240 kilometers) tributary of the Fraser River. The landslide took place around 14 miles (22 km) upstream from where the Chilcotin joins the Fraser, dumping roughly 640 million cubic feet (18 million cubic meters) of earth and rock across the waterway and completely blocking its flow, according to an emergency statement from the British Columbia government.

Within less than 48 hours, the river had swelled significantly, breaking its banks at several points and forming a debris-filled lake behind the blockage, images from NASA's Earth Observatory show. The stretch of the Chilcotin between the landslide and the Fraser River was left almost completely dry.

Regional authorities quickly issued evacuation orders for residents living close to the banks downstream of the blockage, fearing that the rocky dam would eventually break and release a surge that could cause flash flooding or trigger further landslides downstream. It is unclear how many people were evacuated.

Related: See all the best images of Earth from space

On Aug. 5, part of the dam finally broke, unleashing a torrent of water that violently raced through the previously emptied riverbed. Despite the water flowing at more than 12,000 cubic feet (3,500 cubic meters) per second, the surge of water did not cause any major damage.

However, the landslide will likely have a major impact on the river's resident sockeye salmon (Oncorhynchus nerka), most of which were likely downriver of the landslide when it occurred, according to a statement from the Tŝilhqot'in Indigenous nation.

Not only did some of the fish likely die after being stranded and suffocating in the dried-up section of the river, but any survivors that were in the Fraser River will now have a much harder time reaching their spawning grounds in Taseko Lake — around 45 miles (72 km) upstream of the remaining obstruction, according to NASA's Earth Observatory.

The International Union for the Conservation of Nature (IUCN) Red List of Threatened Species currently lists sockeye salmon as "least concern" due to rising numbers worldwide, but the Taseko population is listed as “endangered” by the Committee on the Status of Endangered Wildlife in Canada and was already experiencing record low levels of spawning before the landslide occurred. As a result, Tŝilhqot'in conservationists are worried about the population's future survival prospects.

Subsequent satellite images released by NASA's Earth Observatory show that the change in the Chilcotin River's flow has caused the water to pick up large amounts of sediment from the river bed, turning the waterway and the Fraser River yellow-brown. Although this effect will be temporary, the changes in water quality could further affect freshwater species downriver.

This is not the first time a landslide has impacted the Chilcotin River. The Tŝilhqot'in people named the area surrounding the waterway Nagwentled, meaning "landslides across the river" in the Athabaskan language, according to NASA's Earth Observatory. However, this is one of the most significant obstructions along the river in recent times.

Beachgoers in California recently found a rare, giant "doomsday fish" that folklore claims is linked to earthquakes. In a strange coincidence, the region then experienced a quake just two days later.

The 12-foot-long (3.7 meters) short-crested oarfish (Regalecus russellii) is only the 20th oarfish to wash up in California since 1901, according to a statement released by the Scripps Institution of Oceanography at the University of California, San Diego. These fish live in the deep sea and are rarely seen by people. They also have a reputation in Japanese folklore as harbingers of disaster.

"There's this thought that they're a doomsday fish or a bad omen and that they seem to signal things like tsunamis or earthquakes," Zachary Heiple, a doctoral student at the Scripps Institution of Oceanography who helped recover the oarfish, told Live Science.

The oarfish washed up near San Diego on Aug. 10. On Aug. 12, a magnitude 4.4 earthquake hit Los Angeles. However, the two events are unlikely to be related.

Heiple pointed to a 2019 study published in the journal Bulletin of the Seismological Society of America that found any supposed link between oarfish sightings and earthquakes was pure superstition.

"There didn't really seem to be any correlation," Heiple said. "But it's a really interesting tidbit because it shows how oarfish and human history have interacted throughout time. "

Related: Gigantic sunfish that washed up on Oregon beach could be the largest of its species ever found

Oarfish can grow to 36 feet (11 m) long and could have inspired ancient tales of sea monsters, according to the Florida Museum of Natural History. The ribbon-like creatures live up to thousands of feet deep in oceans around the world, filter-feeding on krill and crustaceans.

Researchers don't yet know why the oarfish washed up in San Diego, but it ended up in a shallow reef between La Jolla Cove and La Jolla Shores. A group of current and former marine scientists happened to be snorkeling and kayaking on the reef that day.

Emily Miller, a research associate at California Sea Grant, who was part of the group, told Live Science in an email that she was "bewildered" when a member of the public told her about the shiny, silver fish.

"The visibility wasn't top-tier that day, but the highly reflective surface of the oarfish was still brilliantly obvious underwater," Miller said.

The fish was near the bottom of the reef, so Miller pushed it to the surface and called for help. "I knew immediately that this fish would be a very significant subject of study, and that the researchers at nearby institutions and agencies would want to collect the animal," she added.

The reef is in a protected area, so the researchers secured permission to remove the fish and then worked with members of the public to get the giant animal to shore.

"It was like Christmas morning," Heiple said. "These are very rare, and something like this just doesn't happen very often."

The oarfish went to a National Oceanic and Atmospheric Administration (NOAA) facility where researchers took samples to learn more about the animal. It's not clear why the oarfish died, but it was in good condition, according to the statement.

Heiple is studying the evolution of deep-sea fish and hopes DNA samples will shed light on why oarfish evolved such a bizarre appearance.

"It was really excellent that we were able to preserve this oarfish, and we are getting to take as many samples as we are," he said.