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!

"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

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.

Fast animals get plenty of attention for their incredible feats of speed. But what about animals that move at a slower pace?

"We definitely are programmed to think that speed is good," said James Maclaine, senior curator of fish at the Natural History Museum in London. "For a lot of animals, that doesn't make any sense to them at all."

So what is the world's slowest animal? And what does survival look like when speed isn't part of your skill set?

Slow sea movers

These may seem like simple questions, but speed can be defined in different ways. One way to understand and compare animals' speeds is to consider the time it takes them to cover a particular distance. In that regard, the slowest animal could be the sea anemone, which creeps along at just 4 to 6 inches (10 to 25 cm) per hour (0.00006 to 0.00015 mph), usually when it's searching for a new abode; otherwise, it remains stationary.

Not far behind this largely stationary creature is the dwarf seahorse (Hippocampus zosterae), which is widely regarded as the slowest-swimming fish and one of the slowest animals in the world. Partly, that comes down to its upright swimming posture and its tiny dorsal fin, which has limited power to propel the seahorse through the water at that angle. "If you made it move, it would take it an hour to move a meter and a half [or 5 feet]," Maclaine told Live Science.

But this suits the seahorse quite well, as the creature spends most of its time tethered to its seagrass habitat by its long, prehensile tail, and eats tiny passing crustaceans. "Food comes to it, so that means it doesn't need to be fast," Maclaine explained. What's more, these animals don't have many predators because they're well armored with defensive, bony plates and, therefore, have little need to escape.

Related: What is the fastest animal on Earth?

The only time these seahorses pick up their pace is when they're ready to reproduce, Maclaine said. "This is really quite special, because they dance with each other … They sort of synchronize their movements." The choreography can last hours, he added. "That courtship dance is the big seahorse movement."

In the ocean's deeper layers, the Greenland shark (Somniosus microcephalus) is a coldwater behemoth that can reach lengths of 24 feet (7.3 m). This ancient creature drifts along at an incredibly leisurely 2 mph 3 km/h. The Greenland shark lives in frigid waters where it scavenges on dead sea creatures. "You don't need to move very fast for that, so it has slowed right down," Maclaine said.

Locomotion on land

On land, the slowest-moving animal would likely be the banana slug, which moves at the extremely leisurely pace of 0.006 miles (0.0096 km) per hour, according to Jon Ablett, senior curator of molluscs at the Natural History Museum in London.

While it's difficult to get definitive estimates on animal speeds, molluscs are notably slower than other animals, Ablett told Live Science in an email: "Some molluscs don't move at all in their adult life, some bivalves are permanently sessile." It's not just that these animals are small, Ablett added. "They are slow moving in general — if you think of other groups like beetles, spiders or ants for example, they are small, often smaller than slugs and snails, but much faster."

Despite this, there is a variety of speeds in the mollusc kingdom. For instance, the common garden snail (Cornu aspersum) glides along at a surprisingly speedy clip of 0.03 miles (0.048 km) per hour, Ablett said.

Other standout slow movers on land are the Galápagos giant tortoise (Chelonoidis niger), a reptile with a limited range of speed, which also takes a long time to cover a short distance. These reptiles saunter along at about 0.16 mph (0.26 km/h). To put that into perspective, humans, who are similar in size, walk at about 2.8 mph (4.5 km/h).

Meanwhile, mammals that live in trees are among the slowest animals around. The slow lorises (Nycticebus) are a group of diminutive primates that, as their name suggests, move around in the trees at a gradual, deliberate pace, cautiously swiveling around their large eyes to observe the surrounding environment as they go. While they can stay motionless for hours, these creatures move at about 1.1 mph (1.8 km/h).

Speed and size

There's another way to measure speed, which is to factor in body size. Some biologists consider this a more accurate way to compare animals. Consider for example that a human can cover a much greater distance in one second than an ant can. Yet considering its tiny body, the ant is covering more distance and much faster, relative to its size, than we are.

A creature's range of speed is another factor to think about when identifying the world's slowest animal, said Rory Wilson, professor of aquatic biology and sustainable aquaculture at Swansea University in Wales. For example, some snakes may creep along almost imperceptibly but then rapidly lash out to ambush and catch their prey.

Factoring in these various traits, Wilson thinks that for the title of slowest animal there's no contest for three-toed sloths (Bradypus).

"From the perspective of someone who studies animal movement in the broadest sense — not just getting from one tree to another, but also the speed of movement when they react to stimuli — it is really striking how slow sloths are," Wilson told Live Science. These animals can hit speeds of 1 mph (1.6 km/h), but several estimates suggest it's typically in the realm of just tens of meters.

In addition to taking a long time to cover little ground, sloths are worthy of the slowest-animal crown because all of their motions unfold at a glacial pace. "When I saw my first wild sloth, I couldn't believe how slow it was," Wilson said. "Everything is like tai chi."

Like many other animals that live life at a relaxed tempo, sloths require some adaptations to compensate for the missing benefits of speed. Sloths have evolved to be masters of camouflage, because if they're spotted by predators they have no ability to escape. These animals are also strikingly strong, with three times our human strength, giving them stability in the trees where nimbleness and speed might otherwise help keep them safely aloft.

The sloths' unhurried pace is also connected to a slow metabolism that allows them to survive on small amounts of energy-poor food. It can take them days to digest their diet of leaves, and they descend from the trees just once a week to defecate.

"The question is, why would they be that slow? What do they get out of it?" Wilson said. The simple answer is that speed requires power, and power demands energy, which can be difficult and expensive to acquire, Wilson said. Sloths have managed to circumvent that need by thriving on very little — and that means a life in the slow lane. "If your whole lifestyle is 'I'm chilling so I don't need to eat much, I can eat rather poor quality food so I can digest it over days instead of hours, the energy return is very slow, and that's OK because I'm very slow' — it all works out extremely well," Wilson explained.

Animal quiz: Test yourself on these fun animal trivia questions

Researchers have discovered the remains of an ancient shark deep inside the world's longest cave system.

The newly discovered shark, plucked from the walls of Mammoth Cave in Kentucky, lived around 340 million years ago and was equipped with a curved row of teeth that it used for crushing its prey.

Macadens olsoni was a small shark, less than 1 foot (30 centimeters) long, and likely fed on mollusks and worms, according to a statement released by the National Park Service (NPS).

"This discovery is a remarkable addition to our understanding of ancient marine life and underscores the importance of preserving and studying our natural history," Barclay Trimble, the superintendent at Mammoth Cave National Park, said in the statement.

Related: 340 million-year-old 'nail tooth' shark found deep inside Mammoth Cave in Kentucky

The rocks of Mammoth Cave formed around 320 to 360 million years ago and were once beneath a shallow saltwater sea, called the Mississippian Sea. The cave system itself is much younger, and only formed about 10 to 15 million years ago, when water from rivers and streams on the surface sank into the rock and carved out the cave's passages found today, according to NPS.

The exact length of Mammoth Cave is unknown, but explorers have mapped more than 426 miles (686 kilometers) of it, and are still uncovering new passages. It hosts a treasure trove of ancient fish fossils — more than 70 different long-lost species have been identified within its walls so far.

The latest find was extracted from the Ste. Genevieve rock formation and dates back to the Carboniferous period (358.9 million to 298.9 million years ago). The genus name, "Macadens," honors Mammoth Cave, while the species name, "olsoni," honors Rickard Olson, a retired park scientist who has played a key role in documenting these fossils, according to the statement.

The M. olsoni discovery helps researchers better understand the ancient ecosystems now preserved in Mammoth Cave, which may have once been similar to reefs.

"This finding not only enhances our knowledge of ancient marine ecosystems but also emphasizes the critical role of paleontological research in our national parks," Trimble said. "Every discovery connects the past with the present and offers invaluable educational opportunities for students and the public."

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?

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?

An octopus has been spotted catching a ride from an unlikely marine friend: a superfast shark.

Researchers captured a video showing the orange-hued octopus clinging to the back of a large shortfin mako shark (Isurus oxyrinchus) as it swims.

This "sharktopus" was spotted in the Hauraki Gulf off the northern coast of New Zealand's North Island during a December 2023 research trip.

"A large metallic grey dorsal fin signalled a big shark, a short-fin mako. But wait, what was that orange patch on its head? A buoy? An injury?" Rochelle Constantine, a marine biology professor at the University of Auckland who was on the research trip, wrote in a statement. "We launched the drone, put the GoPro in the water and saw something unforgettable: an octopus perched atop the shark's head, clinging on with its tentacles."

The researchers were bemused by this bizarre sight, as octopuses usually live on the ocean floor, while shortfin makos spend most of their time swimming near the surface.

"We really don't know how this octopus, that lives on the seabed, came across this 3 m [meters, or 10 feet] mako shark that lives in pelagic — open ocean waters. It really is a mystery — but the ocean is filled with unexpected things," Constantine told Live Science in an email.

Related: Searching for 'Makozilla' — the supersized mako sharks in the North Pacific

Shortfin mako sharks are the fastest shark species in the world, reaching top speeds of up to 46 mph (74 km/h). They can grow as long as 12 feet (3.7 m) and weigh as much as 1,200 pounds (545 kilograms). These sharks are known for their incredible jumping ability, being able to leap up to 20 feet (6 m) out of the water. They usually hunt near the ocean surface but have been spotted as deep as 1,640 feet (500 m). Their diet mostly consists of other fast-swimming fish such as swordfish and tuna, as well as squid and occasionally other sharks.

The researchers watched the strange "sharktopus" for 10 minutes before leaving the odd companions to continue their journey.

"The shark may not be bothered by the octopus — it certainly didn't appear to be bothered as it swam along slowly," Constantine said. "The octopus was keeping all of its tentacles together on the shark's head, perhaps to avoid being seen but it could stay there while the shark was swimming slowly. I suspect the octopus would have dislodged if the shark swam faster."

Shortfin mako sharks are listed as endangered on the IUCN Red List, largely due to their fins being highly prized in the shark fin trade. They also get caught accidentally as bycatch in tuna and swordfish fisheries, especially with longline fishing gear. Their slow rate of reproduction means that they can't reproduce fast enough to keep up with fishing pressure, leading to population declines.

"One of the best things about being a marine scientist is that you never know what you might see next in the sea. By supporting conservation initiatives, we can help to ensure that such extraordinary moments keep happening," Constantine said in the statement.

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

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.

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

Try more science quizzes:

—Animal quiz: Test yourself on these fun animal trivia questions

—Crocodile quiz: Test your knowledge on the prehistoric predators

—Orca quiz: Will you sink or swim?

We don't know exactly when the first animals on Earth appeared, but it's thought to be around 700 million years ago. Around 541 million years ago, at the start of the Cambrian period, hundreds of thousands of new species appeared within a span of about 20 million years — an event known as the Cambrian explosion. Since then, millions — or possibly billions — of species have come and gone. Scientists estimate that 99.9% of all creatures that ever lived have gone extinct.

Researchers think there are now around 7.7 million animal species living on Earth, with thousands more discovered every year. But species are also going extinct at an alarming rate, with many likely vanishing before they've even been formally recognized. Many scientists even say we're entering a sixth mass extinction.

How much do you know about the animals currently living on our planet? Take our quiz to find out. If you need a hint, hit the yellow button. Good luck!

More science quizzes

—Mammoth quiz: Test your knowledge of the ice age beasts

—Evolution quiz: Can you naturally select the correct answers?

—Orca quiz: Will you sink or swim?

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

—Crocodile quiz: Test your knowledge on the prehistoric predators

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 bizarre photograph captures the moment a secretary bird (Sagittarius serpentarius) closes its third eyelid as it catches a locust midflight. The image is one of the winners of the 2024 Royal Society Publishing Photography Competition, which is run in collaboration with the Royal Photographic Society, and recognizes images showing hidden scientific phenomena in the natural world.

The secretary bird was captured by biologist and photographer Peter Hudson, who was named winner of the ecology and environmental science category.

"Secretary birds are closely related to falcons but have evolved a stork-like mode of life, where they stalk around the savannah and feed on locusts, lizards and amphibians by punching them on the ground," Hudson said in a statement emailed to Live Science. "This bird has just caught a locust, and as it swallows its prey, it synchronously closes its third eyelid, the nictitating membrane, across its eyes to protect them from damage."

Related: Shoebill: The human-sized African bird that eats baby crocodiles and kills its siblings

Secretary birds are large birds of prey — reaching around 4 feet (1.2 meters) in height — with an eagle-like body that sits on long, crane-like legs. They're native to sub-Saharan Africa and, while they can fly, they spend most of their time walking through long grasses looking for food.

Hudson's image reveals the bird's third eyelid, which looks like a blue ball sitting in the eye socket. According to the National Audubon Society, the third eyelid sits beneath the upper and lower lids. It's hinged at the inner side of the eye and moves horizontally across the eyeball to keep it free of dust, wind and hazards — giving the eyelids the nickname "nature's goggles."

An aerial image of four sharks hunting in a school of fish was named overall winner of the competition. It was taken by Angela Albi, a researcher at the Max Planck Institute of Animal Behavior in Germany who studies interactions between sharks and fish.

"Just after sunrise or before sundown, the shallow waters of the Maldives become a clear, see-through surface," she said in the statement. "These are also the moments when we best observe the interactions between reef sharks and their prey. In this frame, captured during a research trip in 2024, a shark on the far left shifts suddenly from swimming calmly within the school to initiating a hunt, its body posture standing out from the others. While we still don't know what triggers these attacks, we analyze videos to study how sharks hunt and how their prey responds collectively."

The winners from the astronomy, earth science and microimaging categories can be seen below.

A gang of orcas off the coast of Mexico have learned how to hunt whale sharks — the world's largest shark species — and their tactics are brutal.

One male individual was present at the majority of these hunting events, researchers say, suggesting he may be driving this predatory behavior.

"The animals have shown us over and over again that they are extremely good at developing highly specialized strategies to target specific prey," Volker Deecke, a professor of wildlife conservation at the University of Cumbria in the U.K., told Live Science in an email. "This is a fascinating behaviour." Deecke specializes in marine mammal biology but was not involved in the new study.

Whale sharks (Rhincodon typus) are the largest fish in the sea, weighing up to 40 tons (36 metric tons) and usually growing up to 40 feet (12 meters) long, according to the National Ocean Service. The largest of these ocean giants can reach lengths of over 60 feet (18 m) — about as long as a bowling lane.

In comparison, orcas (Orcinus orca), also known as killer whales, rarely surpass 32 feet (10 m), according to the National Oceanic and Atmospheric Administration (NOAA) Fisheries. However, researchers have discovered that these formidable predators have developed strategies to take down the marine mammoths. The findings were published Nov. 29 in the journal Frontiers in Marine Science.

The researchers characterized this new hunting behavior by analyzing photos and video footage from the southern Gulf of California, taken between 2018 and 2024. They observed four such hunting events in total.

Related: Orcas start wearing dead salmon hats again after ditching the trend for 37 years

The orcas started by hitting the whale sharks at high speeds, in order to stun them and turn them upside down. In this position, the sharks were unable to move or escape into deeper water, study co-author Jesús Erick Higuera Rivas, a marine biologist at non-profit research organization Conexiones Terramar, said in a statement.

The orcas then attacked the whale sharks' pelvic area, causing them to bleed out and giving the orcas access to the sharks' nutrient-dense livers.

The researchers didn't actually see the orcas eating their livers, but the organ is known to be a favorite delicacy among orca pods elsewhere.

In three of the four recorded events, a large male adult orca called Moctezuma engaged in the group hunt. The fourth event was orchestrated by females that had previously been spotted with Moctezuma, suggesting he may have been teaching these tactics to other members of the pod. However, this theory has yet to be confirmed.

It is also unclear whether this is a new behavior or if it has been going on for years without detection. "More likely the increase in human activity (and availability of affordable waterproof cameras) has meant that a rare behaviour that has been present for some time is more likely to be detected (and recorded)," Deecke said.

"Studies across the globe have shown that individual killer whale groups and populations specialize on a few prey types that they hunt using very specialized hunting techniques. The fact the animals in the Gulf of California have evolved a strategy to attack and consume whale sharks is therefore not that surprising, but fascinating nonetheless."

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.

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.

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.

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.

The White Shark Café is a mysterious meeting spot for great white sharks (Carcharodon carcharias) located in the Pacific Ocean, halfway between Baja California and Hawaii. The sharks undertake a month-long journey from their usual habitat off the coast of California to reach the Café. The region was long thought to be an oceanic desert hosting very little life, raising questions about its role in the life of great whites.

Barbara Block, a professor of marine sciences at Stanford University's Hopkins Marine Station, came up with the name "White Shark Café" while researching the migration patterns of North Pacific great whites using electronic tags. Between 1999 and 2000, Block and her colleagues tagged six sharks off the coast of California, and examined their movements for up to six months.

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

Four of the sharks swam southwest toward Hawaii and remained in a remote patch of ocean the size of Colorado throughout winter and spring, revealing for the first time that North Pacific great whites spend extended periods of time in the open sea. The data also showed that the sharks took unusually deep dives down to about 1,500 feet (450 meters) below the surface in this location, leaving the scientists puzzled.

Over the following years, the researchers realized it wasn't just a handful of adventurous great whites that were migrating offshore but large crowds of them, deepening the mystery. The Californian coast offers great whites a rich food buffet of elephant seals and other marine mammals, so scientists couldn't fathom why the sharks traveled to a seemingly barren spot in the middle of the Pacific.

In 2018, a research team led by Block followed great whites to their Pacific lair to understand why the Café has become a gathering place. The researchers tagged 20 sharks using satellite tags that were programmed to drop off after a predetermined period of time, and later retrieved 10 tags containing information about the sharks' movements and deep-diving behavior. They also collected information about environmental conditions and marine life at the Café.

Instead of a watery desert, the researchers found an ocean oasis, according to a statement released at the time. Deep layers of microscopic algae and rich communities of marine animals showed the Café was much more lively and biologically productive than scientists thought, suggesting great white sharks gather there every year for food. Why the sharks actively seek out this food instead of the cornucopia that is their usual habitat is unclear.

"We found a high diversity of deep-sea fish and squids (over 100 species), which in combination with observations made by the ROV [remotely operated vehicle] and DNA sequencing, demonstrate a viable [food source] to support large pelagic organisms such as sharks and tunas," Block said in the statement.

The sharks' diving patterns mirrored the daily cycles of animals that migrate up and down the water column, suggesting great whites were following their food. But the dives also raised questions about a possible mating behavior, which researchers are still trying to work out.

Male sharks increased their diving activity in April, plunging up to 140 times per day, but the habits of females remained the same, the San Francisco Chronicle reported at the time. Researchers are still scratching their heads about what this might mean, but some experts suggest males could be diving deeper to increase their chances of mating.

Discover more incredible places, where we highlight the fantastic history and science behind some of the most dramatic landscapes on Earth.

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."

Great white sharks split into three distinct groups about 100,000 to 200,000 years ago and seldom mingled, a new study shows. The findings suggest that if one of these populations goes extinct, it cannot be replaced, the study authors said.

In the study, published July 23 in the journal Current Biology, scientists sequenced the genomes of 89 great white sharks (Carcharodon carcharias) sampled worldwide. Their results pointed to three distinct groups that diverged over time and did not interbreed. These groups are found in three locations: the North Atlantic/Mediterranean, Indo-Pacific and North Pacific oceans. 

"Now we understand that if you wipe out sharks in a particular area, they're not going to be repopulated by sharks from another lineage," study co-author Leslie Noble, a molecular evolutionary ecologist at Nord University in Norway, told Live Science. "The so-called global population of white sharks has now shrunk to these three very discreet units. And it's really quite concerning."

Like salmon, female sharks always return to their birth site to drop their pups, Noble said. This means that the sharks' mitochondrial DNA, which they inherit only from their mothers, "is a bit like a passport — it shows exactly where they come from," Noble said. Earlier studies have looked at white sharks' mitochondrial genome to study their genetic diversity. However, a portion of this maternal DNA is prone to mutation, making them unreliable references for tracing the lineage divergence.

In the new study, Noble and his team sifted through hundreds of thousands of genetic markers by analyzing variations of white shark DNA at a single nucleotide level — its basic building block. 

The scientists laid out the whole genome information of 89 white sharks sampled worldwide and grouped related genetic sequences using a statistical algorithm. They found that the sharks were segregated into three distinct populations. 

The team traced the history of these sharks by identifying when the genetic makeup of a shared ancestor began to diverge. These analyses suggested that the shark lineages split about 100,000 to 200,000 years ago during the Penultimate Glaciation Period — an ice age that saw sea levels fall up to 490 feet (150 meters) lower than current levels. 

It is still unclear why these populations split in the first place. Noble suspects the drop in sea level and changes in ocean currents and temperature may have created a biogeographical barrier for these sharks.

"We don't find genes moving across those [geographical] boundaries," Noble said. "That to us suggests that there must be some sort of a selection, which is making those different lineages adapted to the particular areas they're in."

Mysteriously, the only evidence of interbreeding was the presence of a hybrid shark — a mix of the Indo-Pacific and the North Pacific lineage — in the Bermuda Triangle. It is possible that more instances of interbreeding have occurred but that the offspring of these hybrids were lost through natural selection, Noble said. 

Related: Great White Sharks Gather in Droves in the Middle of Nowhere, But Why?

The International Union of Conservation of Nature (IUCN) considers the great white shark vulnerable to extinction. These sharks lost about a third of their population between 1970 and 2018, but thanks to global protection efforts, their populations are slowly increasing.

To Noble, the existence of three lineages means conservation efforts should focus on maintaining each unit of the white shark population. If one population starts to stray into another's territory, interbreeding could occur and produce offspring that may not survive. 

The disappearance of these apex predators would also have huge implications for humans. "Our fate is intimately bound with the great whites because we get about 20% of our protein from marine ecosystems, which the great whites keep healthy," Noble said. "So [if] we lose the great whites, we might lose a lot of our protein from these ecosystems."

Captive female sharks at an aquarium in Italy keep reproducing on their own with no males involved, indicating that it could be a vital survival mechanism, according to a new study.

In the study published July 26 in the journal Scientific Reports, the scientists documented repeated asexual reproduction in two common smooth hound sharks (Mustelus mustelus), which are classified as an endangered species by the International Union for Conservation of Nature. The sharks are usually found in the Mediterranean Sea and other warm waters but are threatened by illegal fishing.

The two female sharks are in captivity at Cala Gonone Aquarium in Italy and have spent the last 14 years away from males. Since 2020, both females have reproduced asexually, which indicates facultative parthenogenesis.

Parthenogenesis means "virgin birth," in Greek and describes when an egg develops into an offspring without fertilization. While uncommon in vertebrates, this phenomenon has been observed in reptiles such as crocodiles and water snakes, amphibians and some fish.

Related: 8 animals that have virgin births

However, this is the first documented case of facultative parthenogenesis — the ability to reproduce both sexually and asexually — in this shark species. The researchers found that the two females could reproduce parthenogenetically roughly once a year. That rules out the possibility of sexual reproduction because of stored sperm, according to the researchers.

"Remarkably, this finding reveals that parthenogenesis can occur annually in these sharks, alternating between two females, and conclusively excludes long-term sperm storage as a cause," the authors wrote in the study.

In total, the pair has produced four offspring. The first pup was born in 2016, but it died and the remains were not studied. Three more pups have been born since — one in 2020, another in 2021 and a third in 2023. Only one (born in 2021) is still alive. All displayed bite marks on their bodies, which was likely the cause of death for the pups born in 2020 and 2023, according to the researchers.

To confirm the genetic origins of the offspring, the researchers took DNA samples from each of the three pups and compared them to the adult sharks. Their findings showed that in the set of markers tested, the offspring had identical genes to their mothers.

This discovery highlights the importance of parthenogenesis as a survival mechanism in wild populations with declining male numbers, the researchers said.

"These findings greatly enhance our understanding of reproductive strategies in sharks and could inform conservation efforts for endangered species," the authors said in the study.

While the study focused on common smooth-hound sharks, parthenogenesis has been reported in other species, including whitespotted bamboo sharks (Chiloscyllium plagiosum), zebra sharks (Stegostoma tigrinum), and swell sharks (C. ventriosum).

Greenland sharks can live for hundreds of years, but scientists have never understood why. Now, researchers may have finally discovered the secret to the animals' startling longevity: their never-changing metabolism. The surprising finding goes against scientists' previous assumptions and could have major implications for how these animals adapt to climate change.

Greenland sharks (Somniosus microcephalus) have an average lifespan of at least 250 years but can potentially reach over 500 years old, likely making them the longest-living vertebrates in the world.

These sharks dwell in the Arctic and North Atlantic Ocean at depths of up to 8,684 feet (2,647 meters).

The exact reasons for their long lifespans have been hard to pin down. Researchers have long assumed that their longevity was related to their super-cold environments — they can survive in waters as cold as 29 degrees Fahrenheit (minus 1.8 degrees Celsius) — and minimal movements, according to a statement about the latest findings.

But the new research, which was presented at the Society of Experimental Biology Conference held in Prague from July 2 to July 5, suggests the sharks' longevity could be related to their metabolic activity, which does not seem to change over time like it does in other animals.

"This is important for us as it shows the sharks don't show traditional signs of aging," study lead author Ewan Camplisson, a doctoral student at the University of Manchester, told Live Science in an email.

Related: Searching for 'Makozilla' — the supersized mako sharks in the North Pacific

Metabolism is the chemical process in which enzymes break down nutrients into energy and the processes that use this energy to build and repair tissues. In most animals, the rate of metabolism decreases over time. This leads to reduced energy production, slower repair and regeneration of cells, as well as a reduced ability to remove cellular waste products that can cause further cell damage.

To measure the sharks' metabolism in the new study, the researchers took tissue samples from the muscle of 23 Greenland sharks that were caught on the south coast of Disko Island in central Greenland.

The team then measured the activity of five different enzymes in the samples to work out their metabolic rate and their response to different environmental temperatures.

The researchers then calculated the age of each shark by measuring their body length — a 2016 study created a model to estimate the age of Greenland sharks from their total body length which was used here. They found that the sampled sharks ranged from 60 to 200 years old.

Surprisingly, when the researchers compared the sharks' enzyme activity, they found that there was no change across the different ages.

"In most animals, you would anticipate seeing some enzymes have reduced activity over time as they degrade and become less efficient," Camplisson said. But this is not the case with Greenland sharks.

The stable metabolism across Greenland sharks' ages suggests they don't degenerate like other animals do, which is likely the reason for their long lifespans.

Tests also showed all enzymes had "significantly higher" activity at warmer temperatures — a finding that was expected, as enzymes tend to have higher activity at increased temperatures.

"We wanted to investigate if the Greenland shark's enzymes were specifically adapted to work more effectively in cold conditions, but we did not see this trend," Camplisson said. "The higher activity in warmer conditions would suggest that if these sharks were forced into a warmer environment, then their metabolism would increase significantly which would likely alter their lifestyle."

This finding is particularly relevant, as global sea surface temperatures are expected to increase by 2.1 F to 5.8 F (1.2C and 3.2C) by 2100 due to global warming. And the Arctic's average temperature has already risen three times faster than the global temperature, according to the World Wide Fund for Nature.

Camplisson hopes to test more hallmarks of aging and investigate the sharks' metabolism further to better understand how to protect them as global warming impacts their environment.

In 2013, fishers off Southern California reeled in an enormous, 11-foot-long (3.3 meters) mako shark. At over 1,300 pounds (590 kilograms), the animal — dubbed "The Beast" — was one of the heaviest mako sharks ever recorded. 

In recent years, seals along the California coast have been found with wounds indicating they'd been attacked by large shortfin mako sharks (Isurus oxyrinchus) measuring over 12 feet (3.6 m) long. 

Shortfin makos tend to grow to around 7 feet (2.1 m) long, on average, according to the National Oceanic and Atmospheric Administration. But they can get much bigger. In the 1950s, off the coast of Turkey, fishers reeled in a mako measuring over 19 feet (5.8 m) long. 

In the new Shark Week show "Makozilla," shark biologist and wildlife presenter Craig O'Connell went looking for supersized makos to find out if only one shark had grown to a mammoth size, or if the individuals in the North Pacific population are now much larger than they once were. 

Related: Watch hammerhead sharks swim in 'cyclones' around ancient volcano in rare footage

"Are there more absolutely massive makos out there, and how are they related?" O'Connell told Live Science. "Is it one particular family of makos, or is this a characteristic of the entire population along the coast of California?"

Through a series of experiments, the team gathered bite impressions on bait and measured the animals as they swam alongside the boat. One shark was at least 12 feet (3.7 m) long, while an analysis of the bite marks revealed another was at least 14 feet (4.3 m) long.

A final test involved getting tissue samples from another 12-foot mako. This was then compared with DNA from "The Beast" and another large mako caught years earlier. The results showed that the sharks were related — but it was unclear how closely related they were, such or whether they were direct descendants. Inbreeding among the population may explain the link, the team said. 

However, these makos may be bigger than average because of how much food is available off the West Coast. The Marine Mammal Protection Act of 1972 prevented the killing of seals and sea lions, resulting in a buffet for sharks.

"Basically, what we learned is that this characteristic of getting absolutely massive is a characteristic of the general population along the California coastline," O'Connell said. "To me, that's an exciting thing. It means that there's a lot of very big makos out there … and they have the ability to control the entire ecosystem."

The risk, he said, is that fishers are currently allowed to catch two makos per day — a rule that could potentially have devastating consequences for this healthy population. 

"I think it's critically important for people to understand that we need these sharks in the marine environment," he said. "I like to think of the ocean as a giant Jenga puzzle [tower] and the sharks represent that critical piece. If you remove that piece, that Jenga puzzle is going to collapse. And I just think people need to recognize that these animals are super, super important and we should really do everything in our power to protect them."

 "Makozilla" premieres at 10 pm ET on Discovery.  

Name: Tasselled wobbegong (Eucrossorhinus dasypogon)

Where it lives: Western Pacific Ocean, off the coasts of Northern Australia, New Guinea and Indonesia.

What it eats: Fish, crabs, squid, cuttlefish, octopus and other sharks.

Why it's awesome: The tasselled wobbegong is a master of disguise.

These carpet sharks, which grow up to 4 feet (1.2 meters) long, are able to virtually disappear into the ocean floor thanks to their wide, flat bodies and dark, blotchy coloring, which help them blend into the reef. They also have coral-like lobes of flesh that form a beard-like fringe around the head and chin, which breaks up the wobbegong's outline to add an extra layer to its camouflage.

The species name dasypogon comes from the Greek word dasys, meaning "hairy," and pogon, which translates as "beard."

Related: The ancient deep-sea creature that can can choke a shark by spewing slime

Their ability to blend into their surroundings makes them dangerous predators. During the day, wobbegongs rest under reef ledges or in caves. They use a small, whisker-like sensory organ called a barbel, located in the nostrils, to sense their environment and ambush prey that comes too close. These sharks also wave their tails to imitate the movement of a small fish, which can lure in unsuspecting victims.

But at night tasselled wobbegong sharks really come to life, perching on the reef and attacking passing prey. When they spot a target, they lunge upwards and suck the animal into their giant mouths, before clamping down with powerful jaws and sharp, needle-like teeth.

These fish can also dislocate their jaw to eat larger prey — including other sharks. In 2011, while carrying out a survey of fishes off the Great Barrier Reef in Australia, marine biologists spotted a tasselled wobbegong eating a brown-banded bamboo shark (Chiloscyllium punctatum) that was 80% its size.

Wobbegongs pose very little threat to humans but have been reported to occasionally bite divers who come too close. The Florida Museum's International Shark Attack File records 31 unprovoked wobbegong (of various species) attacks since 1580, but none were fatal.

The wobbegong's camouflage also helps to protect them from predators, as they may be eaten by other marine animals, including larger sharks.

Sharks are feasting on fish caught by humans in the Gulf of Mexico after learning to associate boats with food, shark scientists say. 

Instances of shark depredation in the region have increased significantly in the past decade, Marcus Drymon, a shark scientist at Mississippi State University, told Live Science in an email. 

"Although difficult to demonstrate empirically, it does appear that there is [a] shift in behavior (i.e., a learned response)," he said. 

In the new National Geographic "Sharkfest" special "Shark Beach with Anthony Mackie," researchers along the Gulf Coast investigate the impact of this growing conflict between fishers and sharks. "We're fishing in the same spot that the sharks are fishing in," Jasmin Graham, a marine biologist who founded Minorities in Shark Sciences, said in a clip from the documentary. #

Related: Great white sharks are hanging out in the twilight zone and scientists don't know why

"Sharks learn really, really quickly. They learn engine means food," she said. "So they start coming straight for the boats. Now we're in direct competition with them for the same fish, and that's when you get depredation."

Shark depredation affects fisheries worldwide, but it is particularly prevalent in the U.S. and Australia, where sharks and humans often overlap, leading to conflict. The problem is complicated. In the 20th century, humans decimated shark populations, and humans still kill an estimated 80 million sharks per year as a result of demand for their fins and through bycatch. 

But in some regions, protections have enabled shark numbers to rebound. For example, off the coast of Alabama, bull shark (Carcharhinus leucas) numbers increased fivefold between 2003 and 2020; scientists have attributed the population rebound to warmer waters that have enabled the sharks to thrive. 

The popularity of recreational fishing has also increased, leading more sharks to come close to boats to feast. "It's like we opened a buffet," Mackie said in "Shark Beach." 

Fishers are now reporting that shark behavior has changed off Southeastern states, with more sharks circling and lurking near boats, according to a December 2023 report from the South Atlantic Fishery Management Council. In response, many recreational and commercial fishers say they now operate farther offshore to prevent their catch from being taken and their gear from being damaged. 

"Reports from anglers almost unanimously agree that depredation has gotten much worse in the past 5 to 10 years," Drymon said. "Unfortunately, there is a pretty significant risk (to sharks) in terms of retaliation. This has been quantified through surveys with charter captains and commercial fishermen, two groups whose livelihoods are directly impacted by depredation."

In an attempt to solve the problem, the National Oceanic and Atmospheric Administration is assessing bull sharks and sandbar sharks (Carcharhinus plumbeus) — the two species most often implicated in depredation — and collecting data on depredation events through reporting apps. The agency is also looking at ways of protecting anglers' catch, such as shark deterrent tech. 

"They've got to eat; we've got to eat," Graham said. "We've got to figure out how we both eat."

In an email to Live Science, Graham said the issue of shark depredation points to a larger environmental issue: "It tells us our marine ecosystems are unstable and out of balance. We have to ensure there are enough fish to support our ecosystem predators (including humans) and enough healthy habitats for fish so that they can disperse more widely." 

"Shark Beach with Anthony Mackie" will premiere on National Geographic on June 30 and stream July 1 on Disney+ and Hulu. 

Orcas are hunting sharks in the Gulf of California, targeting large species including bull sharks and blacktips, scientists reveal.  

Three orcas, or killer whales, are behind the attacks, and researchers say it is unclear what impact these hunts could have on the ecosystem, and whether sharks will eventually decide to leave the area. 

In a new study published June 4 in the journal Frontiers in Marine Science, scientists recorded three instances of orcas (Orcinus orca) preying on sharks between 2022 and 2023 in the Cabo Pulmo National Park (CPNP), a marine protected area in the Gulf of California, Mexico. 

"The events described here represent the first documented predator-prey interactions between orca and sharks within the boundaries of the marine protected area of CPNP," the scientists wrote. 

On Jan. 9, 2022, a drone filmed six orcas patrolling an area that's known to have numerous blacktip sharks (Carcharhinus limbatus) — which can reach up to 8 feet. In the footage, two adult female orcas, including one called Quetzalli, split away from the rest of the pod to hunt a shark. However, it managed to escape to deeper water. 

On Jan. 21, 2022, local dive guide Carlos Lozano Hernandez spotted orcas attempting to kill a bull shark (Carcharhinus leucas) — a large, aggressive species that can grow to 11 feet (3.3 meters) long. The hunt was "a coordinated attack," according to the study.

"The shark could be seen on surface when one orca charged the shark on its side, missing the shark only to return to try again immediately, then turning upside down and attempting to hit the shark with her tail, a hunting technique known as 'lob-tailing' or 'tail-slapping'," the authors wrote in the study. 

Related: Florida shark attacks caused by heat, not scary orcas, experts say

A second orca chased the bull shark and charged it head on, then tried to smack it with her tail. The shark headed towards a boat, "splashing frantically and erratically," as it tried to put the vessel between it and its attackers, the researchers noted. The orcas circled their intended victim for 30 seconds before leaving the area. 

The last documented attack, which took place on Dec. 6, 2023, was fatal. Although the hunt itself wasn't captured on film, drone and underwater videos showed orcas with bull sharks in their mouths. Two of these orcas, named Niich and Waay, are in the same pod as Quetzalli. 

The phenomenon of orcas hunting sharks has been documented for over 50 years, according to the paper, although seeing it happen is rare. "Orcas have always naturally preyed on sharks and rays in the Gulf of California," said study author Jesús Erick Higuera-Rivas. "They hunt sharks because of the high nutritional content of sharks' liver and guts," he told Live Science in an email.

According to the study, sharks and rays "are likely underestimated in the diet of orcas." 

However, the recent increase in observations doesn't necessarily mean these hunts are happening more. It could be that modern technology, like drones and underwater cameras, is making it easier to spot and record the predation. 

If predation of sharks by orcas is increasing, it's too soon to say whether it could have an ecological impact, according to Higuera-Rivas. "So far we haven't collected enough scientific information," he said. 

In South Africa, two shark-eating orcas scared hundreds of great whites (Carcharodon carcharias) away from the Western Cape — but experts can't confirm if this might happen in the Gulf of California. "The population of the great white shark in South Africa is different from the population of other shark species that inhabit the Gulf of California," Higuera-Rivas said.

Rob Lott, policy and campaign coordinator at the wildlife charity Whale and Dolphin Conservation, who wasn't involved in the study, agrees. "It remains to be seen what the broader implications are for the ecosystem of orcas hunting sharks," he told Live Science via email. 

Apex predators like sharks play a key role in keeping the ecosystem in balance "so there will be consequences for new locations if the shark population relocates," he said. 

Two recent shark attacks on a beach in Florida led to a flood of social media rumors linking the cases to the presence of orcas in the Gulf of Mexico. But this "doesn't make any sense," marine biologist Jesús Erick Higuera-Rivas, told Live Science.

On June 7, three people were injured in two shark attacks off the coast of Walton County, between Destin and Panama City Beach. Victims included a 45-year-old woman who was bitten near Watersound Beach, as well as two teenagers who were injured later the same day, around four miles east of the first attack. 

The same bull shark (Carcharhinus leucas) was likely responsible for all three attacks, Walton County Sheriff's Office representative Corey Dobridnia told USA Today. 

Recent sightings of orcas (Orcinus orca) in the same region led some people to speculate that the killer whales were driving bull sharks closer to the shore, where they were attacking people. Orcas had been seen on June 4 just south of Destin, about 75 miles (120 kilometers) from where the shark attacks occurred.

However, Higuera-Rivas says that the two events are "not connected." Higuera-Rivas studies orca behavior at the Pelagic Protection and Conservation Civil Association in Mexico, including their interactions with sharks and rays. 

Related: Orcas are learning terrifying new behaviors. Are they getting smarter?

Despite observations of some orcas hunting great white sharks (Carcharodon carcharias) off the coast of South Africa and pursuing bull sharks in the Gulf of California, Higuera-Rivas says that the latest attacks are more likely due to the increase in human activity near where bull sharks feed near shore.

Similarly, the sightings of orcas in the region are also due to the rise in eco-tourism. "You see more images online about orcas being in [the Gulf of Mexico], but it's not because the orcas are appearing more and more often," he said. Rather, they're just being noticed more. 

Because orcas have probably always been in the region, but are only now being photographed more, Higuera-Rivas believes the Florida attacks are unlikely due to their presence.

Gavin Naylor, the Director of the Florida Program for Shark Research at the University of Florida, also agrees.

Naylor told Live Science that orcas sometimes target sharks, but this tends to happen quite far off-shore. "There are so many places for sharks to hide away from orcas along the coast," he said, adding that it's unclear why the sharks would be driven to human-populated coasts, specifically. It seems especially unlikely that bull sharks would accumulate near the shore due to orca activity because the sharks also have the ability to hide in freshwater ecosystems.

Instead, Naylor suggests that the bull shark attacks are likely due to the bait fish moving closer to the shore, thus drawing the sharks in.

Recent hot, dry weather in Florida may mean that freshwater output from estuaries has fallen. "When there's less estuarine output, then the saltwater can come closer to the shore than it would normally do, and that brings with it the plankton and the bait fish that eat them," he said. 

With the bait fish come the bull sharks, Naylor said.

Complete fossils from an enormous shark that lived alongside the dinosaurs reveal crucial information about this enigmatic predator — including it being an ancient relative of the great white shark. 

The sharks, from the genus Ptychodus, were first discovered in the mid-eighteenth century. Descriptions of this genus were largely based on their teeth — which could be nearly 22 inches (55 centimeters) long and 18 inches (45 cm) wide, and were adapted for crushing shells — found in numerous marine deposits dating to the Cretaceous period (145 million to 66 million years ago).

Without the ability to examine a fully intact specimen, researchers had hotly debated what the shark's body shape might look like — until now.

"The discovery of complete Ptychodus specimens is really exciting because it solves one of the most striking enigmas in vertebrate paleontology," lead author Romain Vullo, a researcher at Géosciences Rennes, told Live Science in an email.

In a study published Wednesday (April 24) in the journal Proceedings of the Royal Society B: Biological Sciences, researchers have described complete fossils of the shark discovered in limestone quarries in Nuevo León, northeastern Mexico. Its outline was still fully preserved, and its body shape suggests it hunted sea turtles — which could explain its extinction around 76 million years ago as it was competing with other animals that ate the same prey.

The specimens "show an exquisite preservation," because they were deposited in a quiet area with no scavengers, Vullo said. "The carcasses of animals were rapidly buried in a soft lime mud before being entirely disarticulated."

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

Analysis of the fossils reveals this large predator belonged to the mackerel shark group (Lamniformes), which includes great whites (Carcharodon carcharias), mako, and salmon sharks. It grew to around 33 feet (10 meters) long and is known for its massive, grinding teeth, which are unlike those we see in sharks today. 

It was widely believed that Ptychodus fed on invertebrates from the seabed — the ancient relatives of clams and mussels. But the new fossils challenge that, revealing that this ancient shark had a streamlined body shape, indicating it was a fast-swimming pelagic predator. "The newly discovered fossils from Mexico indicate that Ptychodus looked like the living porbeagle shark," Vullo said, but with "unique grinding dentition."

This new information has led the researchers to believe it preyed on large ammonites — a type of crustacean with a hard shell — and sea turtles. 

"Ptychodus occupied a special ecological niche in Late Cretaceous seas," Vullo said, because it was the only pelagic shark that was adapted to eating hard-shelled prey such as turtles. This may explain why it died out around 10 million years before the extinction event that ended the Cretaceous period. "Toward the end of the Cretaceous, these large sharks were likely in direct competition with some marine reptiles (mosasaurs) targeting the same prey," he said. 

Editor's note: The headline of a previous version of this article said Ptychodus was an ancestor of great white sharks. This was corrected to say it was a relative at 6:24 ET on April 24.

Hundreds of hammerhead sharks gather around an ancient volcano in the Pacific Ocean, drawn by secret signals radiating from the seabed, a new clip reveals.

The footage, which features in the third episode of Netflix's new wildlife documentary series "Our Living World," shows a school of hammerhead sharks (Sphyrnidae) circling Cocos Island — a volcanic island in the eastern tropical Pacific about 310 miles (500 kilometers) southwest of mainland Costa Rica.

Cocos Island is a known haven for endangered hammerhead sharks, but scientists still aren't sure how and why so many sharks navigate across swathes of ocean to convene there every year.

"We don't really know how these sharks are doing this," Ben Roy, the series producer of Our Living World, told Live Science. "We know that they've got sensors in their heads and we know that these sensors pick up on the magnetic signature of these cool volcanic rocks."

The island formed when lava erupted from an ancient underwater volcano and solidified, until it eventually rose 12,000 feet (3,660 meters) above the seabed.

For the episode, film crews followed a young female hammerhead shark as she left her coastal nursery and traveled 300 miles (480 km) across the Pacific Ocean to the volcanic oasis, where scientists think the sharks assemble to relax, socialize and find a mate. The female instinctively knew the way to Cocos Island thanks to electromagnetic signals emanating from hardened volcanic rocks on the island's slopes.

Related: Watch great white shark get mobbed by gang of seals in 'incredible and surprising' footage

In the clip, the young female joins hundreds of other hammerhead sharks as they form a vortex around the island. At "the actual moment when all those hammerheads aggregate and start to swim in those cyclones," Roy said his team "got lucky with some cracking behavior."

This isn't the first time sharks have been seen mysteriously congregating. Scientists previously documented a hammerhead shark gathering in the tropical waters of French Polynesia, in the South Pacific Ocean, but that assembly attracted only females. 

Our Living World

The hammerhead shark gathering is just one astonishing scene among many featured in the four-part nature series, which premieres Wednesday (April 17) on Netflix. The show highlights the intricate links that support the huge web of life on Earth, from the invisible fungal networks that nourish forest ecosystems to transatlantic clouds of nutrients that blow from Africa to South America and rain down on the Amazon. 

"The links are what makes this series totally different to anything I've been involved with or seen in terms of wildlife nature shows on the TV, because what we've tried to do is tell a story that shows how individual animal lives and animal behaviors are connected to a much bigger picture," Roy said.

In telling these stories, "we were really looking for the wow," Roy said. "We are potentially the first generation to be able to fully grasp the connectivity of what's going on here and potentially the last generation to be able to put that knowledge to good use."

The hammerhead shark assembly footage fulfills every expectation Roy had for the show, he said. "Talking about those 'wow' revelations — for me that was one of them," he said. "Sharks need volcanoes? Who knew!"

Baby bull sharks are showing up way more often in the waters off Alabama, researchers found.

In a study published March 14 in Scientific Reports, researchers found that the number of bull sharks (Carcharhinus leucas) caught per hour increased five-fold between 2003 and 2020. All the bull sharks captured and released were juveniles, likely because the baby sharks use these sheltered waters to grow and feed.

While bull sharks are among the most aggressive of shark species, beachgoers don't need to worry that the increasing presence of these stout-bodied fish will lead to more shark bites, lead author Lindsay Mullins, a fisheries scientist at Mississippi State University, told Live Science. Despite the misconception that sharks hunt humans, "they're really not interested in you."

However, they may prey on some of the animals that get caught in fishing gear, so fishers may notice more of these juvenile bull sharks feeding on their catch, Mullins said.

Related: Scientists have figured out when the biggest bull sharks are most active — and it's not when official advice suggests

Bull sharks thrive in fresh, brackish and saltwater and can grow to be 11.5 feet (3.5 meters) long. They live in coastal, tropical and subtropical environments, "so they are used to warm waters," Mullins said.

In the new study, scientists reviewed data from the Alabama Department of Conservation and Natural Resources' gillnet survey of the coastline along Mobile Bay. They found 440 bull sharks captured over the study period.

During that same period, average sea surface water temperatures in Mobile Bay increased from 72.1 to 73.4 degrees (22.3 to 23 degrees Celsius). With ocean temperatures increasing around the world, Mullins sees it as a good thing that bull sharks are able to thrive in warming waters.

The presence of sharks in Mobile Bay also shows that the ecosystem is healthy. "Hooray for resilient baby bull sharks," she said.

But although the sharks are currently thriving, this might not always be the case as temperatures continue to rise. "It's definitely not impossible that there is an upper threshold in terms of temperature tolerance that we just have not seen yet," Mullins said.

Mobile Bay's bull shark population is relatively healthy, but globally, bull sharks are vulnerable to extinction, according to the International Union for Conservation of Nature. And all shark species are threatened by fishing and climate change.

Rarely-seen deep-sea sharks have been spotted mysteriously gathering off a seamount near Panama — the first time the species has ever been documented in the area.

In a study published March 8 in the Journal of Fish Biology, scientists confirmed the "atypical" gathering of 12 prickly sharks (Echinorhinus cookei) in the Cordillera de Coiba, Pacific Panama — a 26,000-square-mile (68,000 square kilometers) offshore marine protected area that includes nine mountain ranges, 24 seamounts and a 15,568-foot-deep (4,745 meters) trench.

The elusive prickly sharks, which have bodies covered by thorny, modified teeth, grow up to to 13 feet (4 m) long and may inhabit depths of up to 3,280 feet (1,000 m). "They prefer to be in deeper waters," which makes them difficult to observe, study author Héctor Guzmán, a marine ecologist at Smithsonian Tropical Research Institute, told Live Science. Although information on the distribution of this species is scarce, they have been observed from Oregon and Japan in their northerly range down to Chile and New Zealand.

Scientists believe these gatherings, which took place in May 2022 between 495 and 1,146 feet (151 to 350 m) deep, were "deliberate." . Before this discovery, there had been no evidence that these sharks aggregated. The researchers aren't sure why the sharks were coming together, but it could be to do with feeding. "We saw juvenile hammerheads down there and those are easy targets for the prickly," Guzmán said. It could also be linked to reproduction. The team checked the sharks' claspers — modified pelvic fins used in reproduction — to confirm that both male and female sharks were at the gatherings.

Related: Watch a super-rare dreamer anglerfish with ultra-black 'invisibility cloak' swim like a shadow in the deep sea

The researchers observed the gatherings as they explored two seamounts on the Cordillera de Coiba, not far from Colombian waters, during 11 dives in a three-person submersible — with a camera and robotic arm to collect samples.

Confirming the presence of prickly sharks around these seamounts is important for the conservation of these biodiversity hotspots. "It helps us to justify why we're protecting these highly productive systems," Guzmán said, because focusing on protecting the whole habitat would, in turn, help all the species that use it.

But although the seamount is located inside a no-take zone — where no fishing is allowed — the researchers saw a Colombian vessel illegally fishing nearby for two consecutive days. "We got imagery of the back of [the vessel] where they had plenty of fins of several species of shark" and reported it to the Colombian authorities, he said.

This highlights an important issue. Although the area is protected, it's located in the open ocean, far from the coastline. "There's no way you can have a patrol boat with a couple of rangers in that area," Guzmán said. This is why their project uses satellites to monitor fishing, to enforce protections that are in place on paper, he added.

Scientists have discovered a never-before-seen species of "ghost shark" with a massive head, giant, iridescent eyes and feathery fins in the depths of the Andaman Sea off the coast of Thailand.

The elusive deep-sea creature, named Chimaera supapae, is a cartilaginous fish in the order of the oldest fishes alive today, Chimaeriformes. These ancient fish are distant relatives of sharks and rays.

Scientists described the discovery in a paper published March 6 in the journal Raffles Bulletin of Zoology.

"Chimaera are rare in this region of the world," David Ebert, lead author of the study and program director of the Pacific Shark Research Center at San Jose State University in California, told Live Science in an email.

Related: 'Mind-blowing' deep-sea expedition uncovers more than 100 new species and a gigantic underwater mountain

Chimaeras inhabit the continental slopes and ocean ridges of the deep sea. Found at depths below 1,640 feet (500 meters), these ghostly individuals lurk in dark waters, feeding on bottom-dwelling animals such as crustaceans, mollusks and worms. 

"There were only 53 known species of chimaera in the world; this makes 54," Ebert said. Their deep-sea nature makes them difficult to find, especially in the Andaman Sea, where depths in some areas exceed 14,500 feet (4,400 m).

 The common names of chimaera—  ghost shark and ratfish — come from their big, reflective eyes and rat-like, tapered bodies. Some species can grow up to 6.6 feet (2 m) long. 

The dead immature male specimen was discovered as part of a deep-sea survey project carried out in 2018. The scientists collected it during a bottom trawl in the Andaman Sea between 2,533 and 2543 feet (772 to 775 m) below the surface. Researchers recognized it as a newfound species by its "massive head with short snout" and its large, oval eyes that are over 32% of its total head length. 

The newly described species is a type of shortnose chimaera, measuring 20 inches (51 centimeters) long with broad pectoral fins. Ebert suspects the creature's feather-like frills have to do with "their ability to maneuver over rocky bottoms of high relief."

C. supapae's big, iridescent, green eyes help the animal see in the pitch-black waters. Its dark-brown skin showed no noticeable lines or patterns, and the fish has a dorsal spine on the top of its head.

The species was named supapae after the late Supap Monkolprasit, a scientist from Thailand who spent her life studying cartilaginous fishes. The genus name Chimaera comes from the Greek mythological fire-breathing creature that has three heads — the head of a lion at the front, a goat's head that extends from its back and a serpent tail that ends with the head of a snake.

"Evolutionarily, these chimaeras are among some of the oldest lineages of fishes with the lineage going back 300-400 million years," Ebert said. "The discovery of new species like this chimaera tells us how little we know about the marine environment and how much is still to be explored."

A rarely seen megamouth shark (Megachasma pelagios) was recently spotted in east Africa for the very first time. It was recorded in a market in Zanzibar, where it was being sold after being captured and killed. The recent sighting was only the sixth time a megamouth had ever been found off the coast of Africa. Marine biologist Rhett H. Bennett of the Wildlife Conservation Society explains the implications of the find.

What is the megamouth shark and why is it so rare?

The megamouth is a large-bodied shark found all over the world. Its name, megamouth, comes from its large mouth. Shaped a bit like a tadpole, with a huge mouth that takes up half its head, it was first discovered in 1976 when one got tangled up in a navy boat's anchor chain in Hawaii. Since then, fewer than 280 megamouth sharks have ever been spotted anywhere in the world. There is not a lot known about this species.

Officially the megamouth has been recorded to reach 7 meters in length, slightly larger than a great white shark (which can reach 6.4m). However, most megamouth sharks recorded to date have been less than about 5.5m long. This is about the length of a tiger shark or the height of an adult giraffe.

People may confuse the megamouth shark with the megalodon, the big, prehistoric shark species that was said to be so much bigger than any other shark. But the megamouth is a gentle giant, with no large, sharp teeth. It cruises around quietly, similar to a whale shark.

It is not a top predator that feeds on tuna fish or marine mammals, but rather a filter feeder that feeds on plankton, and is the smallest of only three shark species in the world that are filter feeders. Megamouth sharks are hardly ever seen, which suggests it is likely a solitary type of animal.

What is known about the first megamouth seen in east Africa?

This megamouth shark was caught by an artisanal fishing vessel in Zanzibar's waters, and then landed at a beach on Pemba Island. The shark was sold for about 43,000 Tanzanian shillings (US$17), probably for consumption in the local communities.

It was sad to see the photos of the dead animal laid out on the beach, but definitely an important new record. This was only the sixth megamouth ever seen in Africa, with one previous sighting each in South Africa, Gabon, Liberia, Senegal and Mauritania between 1995 and 2020.

As the only individual megamouth shark ever found along the east coast of Africa, this finding extends the areas of the world's oceans in which the shark is known to live, filling what used to be a gap in its otherwise near-global distribution.

My colleagues, Abdalla S. Abdulla of the Wildlife Conservation Society's Tanzania Marine Programme and David van Beuningen of the Wildlife Conservation Society's Western Indian Ocean Shark Programme, and I analyze thousands of photographs of dead sharks at landing sites, where fisheries offload what they have caught, including unwanted animals accidentally caught in their fishing gear.

We usually see the same 20 to 30 shark species over and over. So seeing the first megamouth ever in this area was a freak record — one of those rare occurrences and one of the most interesting we have had.

How can the shark be extremely rare, yet not endangered?

The megamouth shark is classified as a species of Least Concern on the International Union for Conservation of Nature's Red List of Threatened Species because it is found all over the world. This means it is likely that its numbers are far greater than the 280 that people have recorded to date. The good news is that even these 280 sightings were not all captures by fishing boats. We conclude from this that fishing operations have minimal impact on the species currently. This may be because the animals use habitats not targeted by fishing vessels.

How can marine biologists research this rare creature?

The first ever pregnant megamouth shark to be found washed up in the Philippines in December 2023. It was 5.5m long and each of its unborn pups had been expelled from the mother's body on the shore. This was the first scientific confirmation that the megamouth, like most sharks, gives birth to live young, as opposed to laying eggs.

In time, if multiple records of megamouths occurred in the same place, scientists might want to focus some dedicated research effort in that area. However, for our research program in east Africa, we do not have the resources to pursue that in detail. We would be spending hours and hours in the ocean and might never find another megamouth. This is why it is important to share this kind of information, in order to contribute additional pieces to the megamouth puzzle.

Anyone who comes across a megamouth shark should notify any nature conservation or government fishery department, or make contact with the Wildlife Conservation Society, or the nearest aquarium.

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

New footage captures a lone orca killing and eating a great white shark in just 2 minutes, revealing they do not need to hunt in packs to take down one of the ocean's most formidable predators.

In the video, the shark desperately attempts to flee as the orca follows close behind, before disappearing beneath the surface. Shortly after, the orca is seen swimming away carrying a liver in its jaws. 

In a study published March 1 in the African Journal of Marine Science, scientists confirmed this case was the first ever record of a lone orca (Orcinus orca) hunting and consuming a great white shark (Carcharodon carcharias) without the help of its podmates. 

The incident took place in June 2023 when researchers on a tourist boat saw two orcas — known as Port and Starboard because of their collapsed dorsal fins — south of Seal Island, South Africa. The two orcas already have a reputation for attacking great whites and feasting on their nutrient-rich livers — a new behavior that has led great whites to abandon a popular hunting ground.

After approaching the orcas, the researchers noticed an oily substance floating on the surface, birds diving into the water and "the distinct smell of shark liver," according to the study. The researchers speculated that the pair of orcas may have already killed a shark before the boat arrived.

"Once you've smelled it, you'd recognize it again," lead author Alison Towner, a marine biologist at Rhodes University, told Live Science in an email. She explained that shark liver smells rich, fatty and not altogether unpleasant, but very hard to describe. 

Nearly an hour later, the boat saw an 8-foot-long (2.5 meters) juvenile white shark at the surface with Starboard chasing behind. "The killer whale pushed the shark forward by its pectoral fin while it thrashed on the surface," Towner said. 

By grabbing the shark's pectoral fin and shaking it, Starboard tore the shark open in precisely the right spot to remove its liver. 

Related: Great white shark ripped in 2 was 'loaded' with orca DNA, scientists say

A few minutes later, a shark cage diving boat that happened to be nearby saw Starboard swim past "with a bloody piece of peach-coloured liver in its mouth," according to the study. Port stayed around 330 feet (100 m) away throughout and was not involved in the predation.

"The moment Starboard rapidly preyed on my favorite shark species was both devastating and intensely powerful," Esther Jacobs, the founder of shark conservation initiative Keep Fin Alive, who saw the attack, said in a statement.

Although the onlookers didn't see the moment Starboard removed the shark's liver, as this happened underwater, Towner believes the shark would've been killed instantly. 

The exact mechanism of how orcas shaking a shark can tear it open is still unclear, but more clues arrived the next day when the carcass of a different great white shark — this one measuring 11.5 feet (3.5 m) — washed up nearby. "The interesting stretch marks on its flank may suggest torsion induced by thrashing," Towner said. 

Orcas target sharks' fatty livers because of their high nutritional value. "Shark livers are packed with rich, oily lipids, making up to one third of their body mass in some species," Towner said. 

Sometimes known as the wolves of the sea, orcas have strong social bonds and usually hunt in groups. While they have been known to hunt other species alone — including seals, porpoises, and penguins — this is the first record of a single orca killing a great white. In previous accounts, attacks have involved between two and six orcas. 

This finding may have important conservation implications. "Altering the top predator balance has cascading impacts," Towner said. "With most sharks already facing various man-made pressures, orca predation adds further strain and could be a tipping point in some regions for some species."

A huge shark bit the head off a stranded pygmy sperm whale in New Zealand as a person standing in waist-high water attempted to get the whale back out to sea. The shark, likely a great white (Carcharodon carcharias), returned 30 seconds later to eat the rest of the whale, witnesses said.

The incident took place  in northern Hawke's Bay on the Māhia Peninsula on Sunday (Feb. 25) after a pygmy sperm whale (Kogia breviceps) and her calf got stranded on the beach, Hawke's Bay Today reported.

Chad Prentice, Māhia sole charge police officer, told the newspaper that a witness said the shark was more than 16 feet (5 meters) long and killed the whale instantly.

Related: In rare attack, great white shark decapitates diver in Mexico. But why?

"I am told when the shark hit the whale the first time … it came out of the water and took its whole head off. There are not many sharks that can do that." Prentice said.

The slain whale was 10 feet (3 m) long, according to witnesses. As the rescuer fled for shore unharmed, the shark took away its prey.

"The water was red and about 30 seconds later the shark came back and hit the whole thing and took it out to sea — there is not even an ounce of remains left," Prentice said.

The sperm whale's calf, still stranded after the attack and left without a mother, was later euthanized and will be studied for further insights into what might have caused the stranding, according to Hawke’s Bay Today.

New Zealand is well known for marine mammal strandings. Usually, just one or two animals get stuck in shallow waters, but sometimes big groups strand simultaneously. The largest mass stranding in the country's history occurred in 1918 and involved around 1,000 pilot whales, according to the New Zealand Department of Conservation (DOC).

Many marine mammals are sick when they strand, but there may be multiple factors behind any given event, and researchers still have a lot to learn about the phenomenon.

The DOC warned of the potential for increased shark activity around the Māhia Peninsula in January after about 45 false killer whales and bottlenose dolphins were stranded and euthanized.

"Several shark species feed on whale[s] and dolphins, including their carcasses, and can be attracted to the site of whale strandings. These include sevengill sharks, blue sharks, tiger sharks, and great white sharks," Clinton Duffy, the DOC marine technical advisor, said in a statement at the time.

Daren Grover, the general manager of New Zealand marine mammal charity Project Jonah, told Hawke's Bay Today it's normal for sharks to prey on sick animals and said they are "opportunistic predators."

The number of unprovoked shark attacks spiked slightly across the globe last year, with a high percentage being fatal, a new report reveals. However, these statistics do not indicate that shark attacks are becoming more common, experts say.

In 2023, there were 69 unprovoked shark attacks recorded worldwide where humans did nothing to deliberately initiate the attack — 10 of which were fatal, according to an annual report by the International Shark Attack File (ISAF), which is coordinated by the Florida Museum of Natural History. 

The number of attacks is slightly up on the average of 63 unprovoked attacks per year during the previous five years (2018 to 2022), and the number of fatal incidents was double the number from 2022, when five people were killed.   

The number of fatalities "are a bit unnerving this year," Gavin Naylor, a marine biologist at the University of Florida who runs ISAF, said in a statement. However, the number of bites is still within the normal range and does not represent a major change in shark behavior, he added.

Just over half of last year's unprovoked incidents occurred in U.S. waters, with the highest number of bites (16) in Florida. There were two fatal attacks in the U.S. — one in Hawaii and another in California. Meanwhile, Australia had the highest number of fatal attacks (4) despite recording only 22% of global attacks.

Surfers, swimmers and snorkelers were by far the most likely people to be attacked, accounting for a combined 94% of unprovoked attacks. Most bites were from three shark species; bull sharks (Carcharhinus leucas), tiger sharks (Galeocerdo cuvier) and great white sharks (Carcharodon carcharias).

Related: What is the deadliest shark attack ever recorded?

While these attacks are classified as unprovoked, it does not necessarily mean that the sharks deliberately attacked or killed humans. A large percentage of attacks are caused by mistaken identity when sharks confuse humans with seals or sea lions. When this happens, sharks normally only take a single bite before realizing their mistake. But when they have such a large and powerful bite, this can be enough to make someone bleed out.

The ISAF also reported 22 provoked bites, which occurred when humans either intentionally or unintentionally did something to trigger an attack, such as spearfishing or catching sharks in nets. However, the report does not state how many of the provoked attacks were fatal.  

In one of the most unusual and gruesome shark attacks from 2023, a great white shark bit and decapitated a scuba diver who was fishing for shellfish in Mexico. This incident, which was pretty much unheard of among shark scientists, is classified as a provoked attack because the victim's activities could have inadvertently caused the shark to attack.

Comparing bite statistics year-on-year is not a very accurate way of assessing long-term trends in shark attacks, experts warned. For example, last year's number of lethal bites was double the total from 2022 but the same as the number from 2021 and only one more than 2020's total. So although the number of deaths increased this year, it is not an unusually high number.

When scientists look at more long-term trends, the number of reported shark bites has more than doubled over the past three decades. However, this is mainly because there are more people in the water and there is a greater emphasis on people reporting non-lethal shark bites due to wider public interest in these attacks thanks to shark movies like "Jaws," Naylor said. 

Overall, the chance of getting killed by a shark is 1 in 4.3 million, according to the ISAF. In comparison, the chance of being killed by lightning is 1 in 80,000, and the odds of being killed by fireworks are 1 in 340,000. 

On the other hand, humans kill around 80 million sharks every year, around 25 million of which  belong to threatened species.

Two new shark species that lived 325 million years ago have been discovered in Kentucky's Mammoth Cave National Park and northern Alabama. The sharks would have lived in an ancient seaway that existed before the supercontinent Pangaea formed, locking them away in the fossil beds we see today.

The two new species have been identified as Troglocladodus trimblei and Glikmanius careforum. Both are ctenacanths, ancient cousins of modern sharks with defensive comb-like barbs on their spines.

Because the fossil specimens in Mammoth Cave aren't exposed to the elements, they are often much better preserved, and retain much more detail, than fossils found on the surface. 

"In such a stable environment, those things look like they just came out of the shark's mouth yesterday," John-Paul Hodnett, a paleontologist at the Maryland-National Capital Parks and Planning Commission who works with the National Park Service's paleontology program, told Live Science.

T. trimblei is thought to have reached about 10 to 12 feet (3 to 3.6 meters) long. "They have kind of like forky-looking teeth," Hodnett said, which is the reason for the name Troglocladodus, meaning "cave branching tooth." The species name, trimblei, honors Barclay Trimble, the superintendent at Mammoth Cave, who found the first specimen in 2019.

G. careforum would also have been about 10 to 12 feet long and had a powerful bite that allowed the predator to eat other sharks, as well as bony fish and orthocones (ancient squid relatives). Hodnett said the primordial predators were "cruising around, probably behaving similar to what we see in lemon sharks or gray sharks."

Mammoth Cave is the world's longest cave system, with over 420 miles (676 kilometers) — about the distance from Boston to Washington, D.C. — of passages cut into the limestone by underground streams and rivers.

Experts have been examining Mammoth Cave's lengthy passages as part of the Paleontological Resource Inventory, an ongoing survey of the fossil records in various U.S. national parks. "It turns out, they [Mammoth Cave's passages] have scores and scores of fossilized sharks," Hodnett said.

T. trimblei was identified as a new genus and species through adult and juvenile teeth in Mammoth Cave and the Bangor Formation in Alabama. To get to the first T. trimblei specimen, "you have to crawl on your hands and knees for a quarter mile [nearly half a kilometer]," Hodnett said. "And that hurts, for me, after a while."

Related: Massive graveyard of fossilized shark teeth found deep in the Indian Ocean

G. careforum was identified through teeth found at Mammoth Cave and the Hartselle and Bangor formations in Alabama. A partial set of jaws and gills from this species was also in a Mammoth Cave passage that was so small, Hodnett couldn't fit in it. Because of their fragility, the fossils still haven't been extracted. 

These two shark species would have hunted close to shore in an ancient seaway connecting North America, Europe and northern Africa at the time, and where Kentucky and Alabama are located today. This seaway disappeared as Africa collided with North America and Europe during the formation of Pangaea. 

A newborn great white shark has been spotted in the wild for the first time, researchers have announced. 

The ghostly white pup was photographed off the coast of California on July 9, 2023 and was nothing like any great white shark documented before. 

Wildlife filmmaker Carlos Gauna and University of California, Riverside biology doctoral student Phillip Sternes, who found the unusual pup, noticed the 5-foot (1.5 meters) shark was thin, short and had rounded fins — a trait usually seen in embryos. It was also entirely white. They documented the sighting in a study published Jan. 29 in the journal Environmental Biology of Fishes. 

Great whites (Carcharodon carcharias) are the largest predatory sharks in the world today and can grow to be up to 21 feet (6.4 m) long as adults. The researchers think the pup was just hours old: "Maybe one day old at most," Sternes said in a statement. 

The unique sighting, which was captured via drone, could help answer one of the biggest mysteries about great white sharks. "Where white sharks give birth is one of the holy grails of shark science. No one has ever been able to pinpoint where they are born, nor has anyone seen a newborn baby shark alive," Gauna said in the statement. "There have been dead white sharks found inside deceased pregnant mothers. But nothing like this."

Related: Great white sharks are hanging out in the twilight zone and scientists don't know why 

On closer inspection, they noticed that the pup was covered in a white film that the pup was shedding as it swam. Great white sharks usually have countershading on their bodies — a gray back and white underside — but the authors think the baby shark was white because pregnant female white sharks produce a milky fluid called "uterine milk" for her embryos to consume.

"I believe what we saw was the baby shedding the intrauterine milk," Sternes said. However, the authors noted it could also be caused by an unknown skin condition. 

This potential newborn was spotted around 1,000 feet (305 m) from the beach. Large, apparently pregnant, females have been seen in that location before, indicating they may give birth in the area. 

"This may well be the first evidence we have of a pup in the wild, making this a definitive birthing location," Sternes said, although the authors noted that some scientists believe white sharks may give birth further offshore.

Knowing where great white babies are born is important for the conservation of the species, which is listed as vulnerable to extinction. "Further research is needed to confirm these waters are indeed a great white breeding ground. But if it does, we would want lawmakers to step in and protect these waters to help white sharks keep thriving," Sternes said. 

An estimated 80 million sharks are dying in fisheries each year despite global regulations aimed at protecting them from finning, scientists have discovered. 

In a study published Jan. 11 in the journal Science, researchers used data from 2012 to 2019 — when legislation to protect sharks from finning increased tenfold — and found that annual shark mortality rose from 76 million in 2012 to over 80 million in 2017. Of those shark deaths, 25 million, or over 30%, represented threatened species. 

The researchers reviewed fisheries data from 150 countries and in the high seas, as well as using computer modeling and interviews with experts — including scientists, governments, environmental advocates and fisheries workers — to check their estimates. 

"We tried to be as proactive as possible in getting the highest-quality data," lead author Boris Worm, a marine ecologist at Dalhousie University in Canada, told Live Science. "I don't think anyone has ever looked at this question at this scale." 

Overfishing is a huge threat for sharks, which are often targeted for their fins or accidentally killed as bycatch. But the study revealed that legislation to prevent shark finning hasn't reduced the number of sharks killed and may have even caused it to increase.

"That's a big concern, because one in three species is threatened with extinction," Worm said.

Related: Super-healing shark regrows its fin after humans cut a huge chunk off

The overall increase was largely caused by mortality hotspots in coastal waters. The study saw shark deaths in coastal fisheries rise by 4%. "Now that finning regulation exists, fishers are keeping the whole shark," study co-author Laurenne Schiller, a fisheries conservation scientist at Carleton University in Canada, told Live Science. 

This could have caused new markets for shark meat to open up. "You might have even incentivized shark fishing in certain places because of this new demand for shark meat," she said. 

The increase in shark mortality correlates with an increase in the value of the shark trade. A WWF report based on the same period (2012 to 2019) estimated that the global trade in shark and ray meat could be worth $2.6 billion. Before this, the market was estimated to be worth $157 million in 2000, rising to $379.8 million in 2011.

Deaths in offshore fisheries decreased by 7%. Offshore fisheries "used to be thought of as the main culprits for finning," Schiller said, but these vessels are no longer allowed to retain certain species onboard. "That means that sharks may get caught, but if they're released, they have a chance of survival," she said.

The authors told Live science that more needs to be done to protect sharks by directly targeting mortality, not just finning. Measures including banning shark fishing, enforcing science-based catch limits, protecting critical areas, and demonstrating the value of live sharks could help to reduce deaths globally. 

"More than anything, this study is showing the global extent of the shark market — not just for fins but also for meat," Schiller said. People can reduce their own impact on sharks by being mindful of their actions — for example, by not buying shark teeth souvenirs, refusing to eat shark (which can be mislabeled, but is can also sometimes be listed under other names, such as huss or rock salmon) and avoiding cosmetics that use shark-derived squalene. 

"It's a solvable problem," Worm said. "But it's a problem that really needs to be tackled now, because sharks have not much time left."

I made an accidental and astonishing discovery while studying the movements of sharks off the coast of Jupiter, Florida. I set out to record the migration routes of silky sharks, named for their smooth skin. Instead, in a story filled with twists and turns, I ended up documenting the rare phenomenon of a shark regenerating a dorsal fin.

Tagging, then trauma

It all started in the summer of 2022, when my team and I tagged silky sharks (Carcharhinus falciformis) as part of my Ph.D. research. Silky sharks are commonly found in the open ocean and grow to be 10 feet long. Scientists know these sharks congregate in South Florida each summer, but where they go the rest of the year remains a mystery — one I hoped to solve.

Local boat captain John Moore took us to a site where sharks are known to gather. We carefully caught and gently attached GPS trackers to the dorsal, or top, fin of 10 silky sharks.

The tags, which are attached like large earrings, do not interfere with swimming and are designed to fall off after a few years. When the tag's antenna breaks the surface of the water, its GPS location is picked up by overhead satellites, hopefully revealing details of the shark's secret life.

I headed home to track their travels from my laptop.

The story took an unexpected turn a few weeks later, when I received disturbing photos from an avid diver and underwater photographer, Josh Schellenberg, who knew of my work.

The photos showed a male silky shark with a large, gaping wound in its dorsal fin, as if someone had taken a satellite-tag-shaped cookie cutter and punched it right through. Josh wondered if this individual was one of the sharks from my study.

When placing the GPS tags, I also place a second tag beneath each shark's dorsal fin that displays a unique ID number, so I was able to confirm the injured shark was one from my study, #409834.

I felt a mixture of relief and sadness. Relief that the shark survived this ordeal; sadness for the scientific data that would now go uncollected.

Silky sharks are often caught by local fishermen in this area but are protected in Florida and illegal to kill or retain. Josh's photos of #409834 showed several hooks in his mouth, so I knew this animal had been captured several times since my team tagged him.

The way the satellite tag attaches means it's impossible for it to naturally rip out of the fin and leave a wound of this shape. Why someone cut off the shark's satellite tag remains a mystery, but perhaps they thought they could resell it or possibly wanted to interfere with research. I never expected to see that shark again.

The return of #409834

Flash forward to one year later, the summer of 2023. I received several photos of silky sharks from John Moore, our boat captain, who is also an avid diver. John was on the lookout for any of our sharks making their seasonal return to Jupiter. In the many shark photos he sent, I noticed a silky shark with an oddly shaped dorsal fin.

I knew immediately it had to be #409834 from the previous summer. A few days later, John was able to get close enough to photograph the ID tag to confirm my hunch. Josh Schellenberg also spotted and photographed #409834. With both John's and Josh's photos, I was able to compare the healed dorsal fin with the freshly injured one.

I wasn't expecting to make a groundbreaking discovery. Simple curiosity led me to start analyzing the photos. But the revelation was astonishing: Not only had the wound completely healed, but the 2023 dorsal fin was 10.7% larger in size than it was after the injury in 2022. New fin tissue had regenerated.

My analysis determined that within 332 days, the shark regenerated enough tissue that his dorsal fin was almost back to 90% of its original size, growing back more than half of what had been cut off in 2022.

The dorsal fin, pivotal for balance, steering and hydrodynamics, is vital for a shark to be able to hunt and survive. Seeing no infection or any signs of malnourishment in #409834 suggests an extraordinary feat of endurance.

Scientists know that sharks have an incredible aptitude for healing — but mechanisms behind these observations are still poorly understood. While limb regeneration has been widely documented in other marine animals like starfish and crabs, there is only one other documented case of dorsal fin regeneration in a shark — a whale shark in the Indian Ocean that regrew its dorsal fin after a boat accident in 2006.

400 million years of resilience

There's a reason sharks have been on Earth longer than trees and have survived multiple mass extinction events that wiped out other species. They are a product of 400 million years of evolutionary adaptations that demonstrate their remarkable resilience and have primed them for survival.

To be able to pinpoint an ability that helps make them so resilient is a major scientific advance — especially considering scientists are still questioning where silky sharks spend most of their time in the Atlantic.

One person's attempt to undermine shark science and harm a shark ultimately proved futile. Instead, the shark's toughness prevailed and led to an amazing discovery about this species. This story also shows there are countless individual people, including scientists like me and shark enthusiasts like Josh and John, who share a genuine love and respect for these animals.

While I'll never know for certain where #409834 spends the rest of the year, I hope he continues to return to Jupiter each summer so we can further assess his progress. Based on the healing rate calculated in my study, we just might see his dorsal fin grow back to 100% its original size.

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

The ocean is teeming with strange and little-seen creatures, but occasionally these enigmas from the deep wash ashore. Sometimes those strandings solve a mystery and other times they raise more questions than they answer. This year was no different, with ghoulish lightbulb-headed fish, a rotting "mermaid" and deep-dwelling pregnant sharks teeming with embryos all making appearances on beaches this year. 

Pacific footballfish 

A ghoulish-looking fish with prickly skin washed up on a beach in Southern California and no one knows why. 

Experts from the California Department of Fish and Wildlife identified a nightmarish creature that washed ashore Oct. 17 at Moro Beach, California as a female Pacific footballfish (Himantolophus sagamius). This rare anglerfish usually lives at depths of 2,000 to 3,300 feet (600 to 1,000 meters) in the Pacific Ocean. 

The hanging lure on its head is called an illicium, and just like a fishing lure, it stretches out from the fish spine and glows to entice prey. Once it lures that prey, it gobbles them up using translucent needle-sharp fangs.

Pilot whales in Scotland

In July, around 55 long-finned pilot whales (Globicephala melas) stranded on a remote beach on the Isle of Lewis in Scotland.

On Traigh Mhor beach, local authorities tried for hours to refloat the whales, but only successfully rescued one. The remainder were euthanized. Researchers suspect that the pod followed after a female whale that beached herself while trying to give birth, according to a statement from the British Divers Marine Life Rescue.

A healthy great white shark

On Oct. 5, a seemingly healthy great white shark was seen thrashing in shallow waters before mysteriously stranding on Broad Cove Beach in Nova Scotia. It eventually died, and even after a necropsy, scientists don't know what killed the animal.

Longnose lancetfish 

In May, a cannibalistic slender-bodied fish appeared on the shore along the coast of Oregon, one of several that washed up within weeks of each other.

It was an elusive  long snouted lancetfish (Alepisaurus ferox), a rarely seen species that lives at depths of around 650 to 3,300 feet (200 to 1,000 meters) in the south-western and central-western Pacific Ocean.  Some theories for strandings include illness, stormy weather conditions and temperature shock from unusually cold waters.

Rotten globster

In September, the remains of a white, mermaid-like creature appeared on the edge of Simberi Island in Papua New Guinea that shocked the locals and left scientists confused. 

The body was so badly decomposed that scientists couldn't identify it, but it was clearly a marine mammal of some kind. When hard-to-identify animal remains wash up,  they are called globsters.

Pregnant great hammerhead shark

An enormous great hammerhead shark (Sphyrna mokarran) was found dead in April near Orange beach in Alabama. After a closer look, researchers at Mississippi State University's Marine Fisheries Ecology (MFE) group found that she was carrying 40 pups.

After a necropsy, the team found that the shark's stomach was completely empty, a common occurrence for pregnant hammerhead sharks, who go months without eating. Her organs showed no signs of illness or disease, so the researchers suspect she died due to human fishing.  

Pilot whales in Western Australian

In a rare spectacle in July, around 100 pilot whales beached themselves on Cheynes Beach in Western Australia.

Wildlife experts and volunteers from the Parks and Wildlife Service worked overnight trying to return as many whales as possible, using slings and vessels to carry them to deeper water. By the end of the day, however, 51 individuals had died. 

The pod was spotted in the shallow waters the night before, swimming huddled tightly together. According to the Whale and Dolphin Conservation Group (U.K.), large strandings can happen because pilot whales live in tight social groups. So when leaders of the pod make navigational errors or get sick, they lead the rest of the pod to shore.

Great white shark ripped in two 

In October, a 10-foot-long (3 m) great white shark (Carcharodon carcharias) was found ripped in half, disemboweled and smothered in orca (Orcinus orca) DNA on a beach in Australia. Scientists confirmed that orcas were the killers, as they are known to attack great white sharks. 

Pregnant megamouth shark

For the first time ever, a pregnant megamouth shark (Megachasma pelagios) washed ashore in the Philippines, complete with her expelled pups.

The discovery has confirmed that this shark does not lay eggs, but gives birth to live young. The bodies of the juveniles have been taken to the National Museum of the Philippines where they will be preserved and studied. 

Bulbous-headed orca 

A mysterious group of bulbous-headed orcas washed ashore in Chile in June. It was only the second sighting of this strange group. The last case of a Type D orca being stranded goes back 67 years ago in New Zealand  

A super-healing shark regrew a section of its fin after suffering a traumatic injury at the hands of humans near Jupiter in Florida, researchers have found.

The silky shark (Carcharhinus falciformis) had a satellite tag fitted to its dorsal fin in June 2022 so researchers could track its migration. A few weeks later, an unknown person cut out the tag and left the shark with a devastating wound. Local diver John Moore saw the shark's tag was missing and contacted the researchers.

"I told him it would be impossible to miss the satellite tag on the dorsal fin, so he would know if it was one of our sharks," study author Chelsea Black, a doctoral student at the University of Miami, told Live Science in an email. "That’s when he sent me the first photo showing the huge hole of where a tag had been."

Black didn't expect to see the shark again, as the injury was extensive and she could no longer track the animal. But, remarkably, almost a year later, the shark returned to the same waters and was photographed with a rejuvenated — albeit slightly stumpy — fin.

"It was shocking!" Black said. "My first reaction was relief that the shark was still alive, as that was a traumatic wound that could affect his swimming ability or create a significant infection."

This is the first time researchers have observed a silky shark regrowing its dorsal fin and only the second recorded case of dorsal fin regeneration in any shark, according to the study, published Dec. 14 in the Journal of Marine Sciences.

Related: Pregnant megamouth shark seen for 1st time after female washes up dead with 7 pups

Silky sharks grow to around 10 feet (3 meters) long and live in the Atlantic, Pacific and Indian oceans, according to the Florida Museum of Natural History. They are vulnerable to extinction due to overfishing, but it's illegal to capture or kill them in Florida.

The silky shark's injuries in 2022 were precise cuts that traced the outline of the satellite tag, so the most plausible explanation is that humans deliberately removed the tag with a sharp object, according to the study. Black doesn't know who removed the tag but doubts their intention was to help the shark.

"It’s more likely that the shark was caught by a fisherman and they either cut out the tag to try and sell it, or they just didn’t want scientists to study them," Black said. "Sharks can be seen as a nuisance to some people, so you can imagine there is a group of people who wouldn’t want us to increase conservation measures."

Black documented the rare fin regeneration by analyzing diver photographs taken 322 days apart. The photographs revealed that the shark lost 20.8% of its fin in the initial injury, and it healed back to 87% of its original size, according to the study.

Researchers are still learning how sharks regenerate their fins because it's so rarely observed. Black thinks the new fin is mostly scar tissue but can't be sure as nobody has ever dissected a regenerated shark fin.

Sharks naturally experience a lot of injuries — often due to aggression and predation attempts from other sharks — so they've evolved to heal quickly. Their healing tricks include immediate anti-inflammatory responses to injuries, according to the study.

"There's a reason that sharks have been evolving for hundreds of millions of years, surviving multiple mass extinction events," Black said. "This story just proves how resilient they can be."