It's a long-held idea that turtles can tuck their heads into their shells when threatened. But is it true? And is this protective trick why turtles the world over have shells today?

The answer is that some types of turtles can, and others can't, experts told Live Science. And even though shells can be protective for some of these reptiles, fossil evidence suggests that shells evolved for entirely different reasons.

Tortoises are one type of turtle that can tuck their heads into their shells. This terrestrial subgroup of turtles emerged 50 million years ago, Tyler Lyson, senior curator of vertebrate paleontology at the Denver Museum of Nature and Science, told Live Science. They typically move slowly, so they rely on their shells to protect them from predators. Most tortoises can draw their heads into their shells, which typically also have a domed shape with more space inside to make that possible.

Several terrestrial turtle species, which split their time between land and water, can do the same.

"Turtles have two ways of tucking the head in," Jason Head, a professor of vertebrate evolution and ecology at the University of Cambridge, told Live Science. "We have what are called the side-neck turtles. They have long necks, and they literally fold the head and neck to the side over one of their arms. And then there are the snake-neck or S-neck turtles, which put a loop into the neck, and can actually pull the neck into the shoulder girdle."

One example is the eastern box turtle (Terrapene carolina carolina), whose bottom shell, known as a plastron, is fitted with a hinge that even allows it to completely close up the shell.

But sea turtles are one group of turtles that cannot pull their heads into their shells. Sea turtles have much sleeker, lighter shells that contain no space for them to tuck their heads inside. "This is to lighten the load," Head said, and it allows sea turtles to swim faster to escape predators.

How turtle shells evolved

So, how did some turtles develop this lifesaving trick? To find out, we need to explore how turtle shells evolved, which takes us back almost 300 million years in the fossil record.

"The turtle shell is a complicated structure. It's made up of over 50 bones," Lyson said. "Bone" is the key word, because fossils reveal that turtle shells are part of their skeletons. And while the modern turtle's shell looks like a solid unit, it's actually made up of two skeletal features that evolved separately.

"The first thing we see in the evolution of the turtle shell is the broadening of the ribs, and we see that in Eunotosaurus africanus," a creature that lived in southern Africa 260 million years ago, before dinosaurs roamed Earth, Lyson told Live Science. Lyson first described Eunotosaurus' contribution to turtle evolution in a 2013 study. Researchers think that these creatures spent time burrowing underground to escape the heat and that the development of wider ribs supported more muscle mass that enabled them to do that.

Then, in Germany, the 2015 discovery of a 240 million-year-old fossil called Pappochelys showed a shell-less animal with wider upper ribs paired with thicker belly ribs — known as "gastralia" — on its underside. By 220 million years ago, an aquatic animal called Odontochelys found in China had developed a fully unified belly plate — the plastron — partly from the expanding gastralia.

"Myself and others think that the evolution of the plastron was a ballast for basically going deeper into the water column," Lyson explained. It's also possible the plastron developed to protect turtles from predators swimming below, he noted.

The first evidence of a fully formed turtle shell comes from 210 million years ago, in the shape of a fossilized creature called Proganochelys, whose thick upper ribs had fused together with dermal bone, forming a closed carapace, attached to a lower plastron. The opening for the turtle's head was formed from shoulder bones that connected the top and bottom of its shell, Lyson explained.

Most evidence suggests that these reptilian creatures, called Pantestudines, ultimately led to modern-day turtles. However, Head noted that similar features — like widened, overlapping ribs — also developed in other animals millions of years ago, including some thought to be more closely related to mammals.

"It's an active area of research, with new discoveries coming all the time," Head said.

The shells of these turtle ancestors developed as a response to varied evolutionary pressures, but today, the turtle's shell is used primarily for self-defense, Lyson noted. "The modern-day function isn't necessarily related to how that feature arose," he said. "It wasn't until you got the full advent of the shell that it was for protection."

The turtle's resilient shell has seen these creatures through almost 300 million years of history, and Lyson thinks it's one reason they've managed to survive three of Earth's five mass extinctions.

"We see the fossil record, and we can see the line in the sand where dinosaurs and lots of other things go extinct," Lyson said. "And we see turtles marching right across that line."

Evolution quiz: Can you naturally select the correct answers?

Turtles and tortoises are both reptiles with shells, but they're not exactly the same. So how can you tell them apart? What's the difference between a turtle and a tortoise?

"All tortoises are turtles, but not all turtles are tortoises," Sydnee Fenn, a reptile keeper at Columbus Zoo and Aquarium, told Live Science. Generally, the reptiles that people call turtles spend a great deal of time in the water, whereas tortoises live on land, according to Genius Vets in San Diego, California.

Many of the differences between turtles and tortoises come from this habitat difference. For example, water-dwelling turtles' shells are usually flattened to help them swim in lakes, rivers or oceans. Tortoises do not swim, so their shells are often shaped like domes instead, Genius Vets notes, which has advantages on land.

"When tortoises are walking, they can flip onto their backs by accident, and the domed shape of their shells can help them flip back onto their feet," Fenn said. "Also, the dome shape allows more space inside, so some can retract all of their limbs into the shell."

Related: Why do turtles live so long?

There are exceptions to this rule, however. For instance, "the pancake tortoise from Africa does not have the domed, solid carapace of other tortoises," Brett Baldwin, curator of herpetology and ichthyology at the San Diego Zoo, told Live Science. "It has evolved a shell that is flat, less heavily calcified, and pliable, which allows it to scurry quickly into rock crevices and wedge itself in by inflating its pliable carapace."

Turtles that spend time in both the water and on land have webbed feet that can help them swim as well as maneuver on the ground if needed. Fully aquatic turtles, such as sea turtles, have flippers, according to Genius Vets. In contrast, tortoises usually have round feet and stumpy legs, the San Diego Zoo notes.

"Having shorter, stouter, more stable legs allows for easier mobility to carry the heavy shell in their terrestrial lifestyles," Baldwin said. For instance, Fenn noted that for desert tortoises, "wide feet help them walk across sand easier, just like camel feet."

Generally speaking, non-tortoise turtles are omnivorous, and tortoises are herbivorous, Fenn said. Because non-tortoise turtles can swim, they can move fast enough to catch prey in the water, thus broadening their diet, she said. In contrast, tortoises are famously slow on land, so they usually stick to plants.

That said, "tortoises can opportunistically eat meat," Fenn said. "They're not going to actively hunt like a tiger would, but if there's meat," such as insects or carrion, "they might eat it." In addition, some turtles, such as the green sea turtle (Chelonia mydas), are herbivorous, according to the National Oceanic and Atmospheric Administration.

Tortoises are found on every continent except Australia and Antarctica, generally in warm to hot environments, such as deserts and jungles, according to the International Fund for Animal Welfare. Turtles live on every continent except Antarctica, and sea turtles spend their lives in oceans spanning the globe, Genius Vets notes. Turtles' aquatic nature helps them survive even when air and ground temperatures get cold, Fenn said.

"They can go to deeper waters where temperature might stay warmer, especially in the winter," she explained. "Some turtles are able to actually breathe underwater through their cloacas, which makes it easier to hide under frozen water. All in all, the fact that they can live in cooler climates opens up where they can be found in the world."

Four endangered baby tortoises have made their highly anticipated public debut at the Philadelphia Zoo as the first hatchlings of their 100-year-old mother, Mommy.

Mommy, a western Santa Cruz Galápagos tortoise (Chelonoidis niger porteri), made international headlines earlier this month for becoming the oldest first-time mom of her species. Mommy's exact age is unknown, but she is around 100 years old and has been at the zoo for more than 90 of those.

The new babies mark the first time Philadelphia Zoo has bred western Santa Cruz Galápagos tortoises in its more than 150-year history. Western Santa Cruz Galápagos tortoises are critically endangered in their native home of the Galápagos Islands, and there are fewer than 50 kept in U.S. zoos.

The zoo unveiled Mommy's four baby girls on Wednesday (April 23), as eager press representatives lined up to get photographs and video of the new star attractions. Wednesday also marked the 93rd anniversary of Mommy's arrival at the zoo.

"THEY'RE FINALLY HERE!" a spokesperson for Philadelphia Zoo wrote in a Facebook post. "Mommy the Galapagos tortoise’s four baby girls have just made their public debut inside the Reptile and Amphibian House in honor of today marking 93 years of Mommy at the Zoo."

Related: World's oldest tortoise still randy at 191 years old

Western Santa Cruz Galápagos tortoises are a subspecies of the Galápagos tortoise, which is the largest tortoise species on Earth. Males — typically larger than females — can grow up to around 1.8 meters (6 feet) in length, and weigh up to around 570 pounds (260 kilograms), according to the San Diego Zoo Wildlife Alliance.

Human activity has driven several Galápagos tortoise species to extinction, while western Santa Cruz Galápagos tortoises number just a few thousand. The tortoises have historically suffered from people hunting them for meat, and have had their ecosystem disrupted by invasive species including predators like cats and rats, which prey on young tortoises and their eggs, according to the International Union for Conservation of Nature Red List.

Mommy's new babies are part of a captive breeding program in U.S. zoos to help safeguard western Santa Cruz Galápagos tortoises. Because Mommy had never bred before, this is the first time she has passed on her genes, helping to keep the captive population genetically diverse and healthy.

"These newest additions represent a new genetic lineage and some much-needed help to the population of this critically endangered species in human care," the zoo's spokesperson said.

The babies could have a long life ahead of them. Researchers don't know the maximum lifespan of Galápagos tortoises, but one individual was recorded reaching the age of 171, according to the San Diego Zoo Wildlife Alliance. Once tortoises reach maturity, they usually remain reproductively active for the rest of their life, and can keep breeding long into old age.

An endangered giant tortoise has become the oldest first-time mom of her species after having her first babies at around 100 years old.

Philadelphia Zoo recently hatched eggs laid by an elderly western Santa Cruz Galápagos tortoise (Chelonoidis niger porteri), named Mommy. Her exact age is unknown, but Mommy has been at the zoo for more than 90 years.

Western Santa Cruz Galápagos tortoises are critically endangered in their native home of the Galápagos Islands, and there are fewer than 50 kept in U.S. zoos. This is the first time Philadelphia Zoo has hatched western Santa Cruz Galápagos tortoises in its more than 150-year history, according to a statement released by the zoo.

"This is a significant milestone in the history of Philadelphia Zoo, and we couldn’t be more excited to share this news with our city, region, and the world," Jo-Elle Mogerman, the president and CEO of Philadelphia Zoo, said in the statement. "Mommy arrived at the Zoo in 1932, meaning anyone that has visited the Zoo for the last 92 years has likely seen her."

Related: World's oldest tortoise still randy at 191 years old

Western Santa Cruz Galápagos tortoises are a subspecies of Galápagos tortoises. These giant tortoises are the largest tortoise species on Earth. Males are usually larger than females and grow up to around 1.8 meters (6 feet) long, tipping the scales at about 570 pounds (260 kilograms), according to the San Diego Zoo Wildlife Alliance.

Human activity on the Galápagos has killed off several of its tortoise species and brought western Santa Cruz Galápagos tortoises to the brink of extinction. Historically, sailors reduced tortoise numbers by hunting them for meat. People have also disrupted their habitat and introduced invasive species such as goats, which compete with tortoises for food, and predators like cats and rats, which prey on young tortoises and their eggs, according to the International Union for Conservation of Nature Red List.

Mommy is part of a captive breeding program in U.S. zoos to help safeguard this tortoise subspecies. She finally reproduced for the first time with a male named Abrazzo — who is also around 100 years old. Abrazzo moved to Philadelphia in 2020 after previously living at the Riverbanks Zoo and Garden in South Carolina, which successfully bred western Santa Cruz Galápagos tortoises in 2019, according to the statement.

Tortoises and other reptiles usually remain capable of reproduction throughout their lives after reaching maturity, so they can keep breeding long into old age. Researchers aren't sure how long Galápagos tortoises can live, but one individual was recorded reaching the age of 171, according to the San Diego Zoo Wildlife Alliance.

After mating, Mommy laid 16 eggs in November 2024. Keepers took the eggs and placed them in an artificial incubator. Like most tortoises and turtles, the sex of hatchling Galápagos tortoises is determined by the temperature at which eggs are incubated. Temperatures below 82.4 degrees Fahrenheit (28 degrees Celsius) produce males, while temperatures above 85.1 F (29.5 C) produce females. The keepers incubated half of the eggs at the male temperature and half at the female temperature to get a mix, but only female eggs have hatched so far, according to the statement.

Ashley Ortega, who coordinates the captive Galápagos tortoise Species Survival Plan at Gladys Porter Zoo in Texas, said in the statement that the program was "thrilled" to help welcome the hatchlings and noted that Mommy becoming the oldest first-time producing female of her species made the feat even more incredible.

"Prior to the hatchlings, there were only 44 individual Western Santa Cruz Giant tortoises in all U.S. zoos combined, so these newest additions represent a new genetic lineage and some much-needed help to the species' population," Ortega said. "We are excited to learn more about how we can replicate this success at other accredited zoos since the team in Philly has accomplished something that was seemingly impossible."

Name: Cantor's giant softshell turtle (Pelochelys cantorii)

Where it lives: Rivers in South and Southeast Asia

What it eats: Fish, crustaceans, mollusks, frogs, insects, birds, small mammals

Why it's awesome: Cantor's giant softshell turtles — named in honor of Danish zoologist Theodore Edward Cantor — spend 95% of their lives completely motionless, buried under mud or sand in shallow rivers with only their eyes and snorkel-like snouts protruding out. But when these unusual-looking reptiles spot something to eat, they can move at lightning-quick speeds.

When they spot fish, frogs or crustaceans, they rapidly extend their necks to strike their prey. They have long claws and powerful jaws that are strong enough to crush bone.

Unlike their hard-shelled cousins, these turtles have leathery, flat, green or brown shells. These large, freshwater turtles are also known as "frog-faced softshells" because of their amphibian-like facial features. They can grow up to 40 inches (100 centimeters) long — although some sources suggest they can grow even larger — and weigh more than 100 kilograms.

Like other soft-shell turtle species, they are thought to have the ability to extract oxygen from the water through their skin, which helps them stay underwater for long periods of time. However, they can only get so much oxygen this way, so they come up to the surface to breathe air twice a day.

These endangered turtles are extremely rare: Between 1985 and 1995, only a single specimen was found. They are native to rivers in India, Bangladesh, Burma, Thailand, Malaysia, Laos, Cambodia, Vietnam, China, the Philippines and Indonesia.

In 2024, the first nesting site of a Cantor was discovered by biologists on the banks of the Chandragiri River in Kerala,India. The researchers used knowledge from local communities to locate the turtle.

Earlier this year, the Western Pacific leatherback (Dermochelys coriacea) left a nesting site in the Solomon Islands and dove 4,409 feet (1,344 meters) beneath the ocean surface, according to the environmental organization The Nature Conservancy. 

At that depth, the leatherback swam deeper than the current Guinness World Record for the deepest turtle dive — 4,199 feet (1,280 m) — set by another leatherback, the deepest-diving reptile species. For context, Navy submarines have reportedly gone to depths of around 2,950 feet (900 m), while the deepest human scuba dive was 1,090 feet (332 m). 

Researchers recorded the dive as part of an ongoing and as-yet-unpublished satellite tracking study to help protect leatherbacks. Another of their tagged turtles swam across the entire Pacific Ocean. Peter Waldie, a marine scientist who leads The Nature Conservancy’s Solomon Islands Program, described the deep dive and epic migration as "truly spectacular."

"Leatherbacks are just an incredible creature to have in the world," Waldie told Live Science. "The ability to swim non-stop all the way across the Pacific, to dive as deep as a Navy submarine on a single breath, it absolutely blows my mind."

Related: What is the deepest-diving mammal?

Live Science approached Guinness World Records about the new claim for the deepest reptile dive. A spokesperson for the company said that the deepest dive by a turtle is one of their "consultant records," which they work with specialist experts to verify — usually after a scientific publication.

"For data-driven science and nature records such as this case, we would generally wait for the findings to be reviewed and published in a peer-reviewed journal before we consider it," the spokesperson said.

Leatherbacks have evolved a variety of adaptations for their deep dives. Even though they're air breathers like us, leatherbacks can hold their breath for much longer and stay underwater for around 90 minutes at a time. Their specialized carapace (upper shell) also contracts and expands with pressure changes to help them survive the deadly pressures of the deep.  

Scientists have a few theories as to why leatherbacks dive so deep, but tracking research has indicated they are swimming down to eat jellyfish, which move up and down the water column, Waldie said

Leatherbacks spend most of their lives out at sea, but females briefly come onto shore to lay their eggs. The Solomon Islands' nesting leatherbacks are part of the critically endangered Western Pacific population, comprising an estimated 1,400 breeding adults, according to the Nature Conservancy.  

"We have reached a point in conservation where we cannot afford to lose any of these creatures," Waldie said. "Every single breeding adult is vital, and every nest we can save that protects the next generation is vital."

Since 2022, Waldie and his colleagues have tagged 17 leatherbacks nesting in Isabel Province on the Solomon Islands, where The Nature Conservancy's local community rangers protect sea turtles and their eggs from poaching and predators. 

The record-breaking leatherback laid her eggs at the Sasakolo nesting beach. Staff named her "Uke Sasakolo," meaning "from Sasakolo." She broke the current depth record on March 25, not long after leaving the nesting grounds, according to Waldie.   

Uke Sasakolo nested during the peak Solomon Islands nesting season, which occurs between November and January. The tagged leatherbacks tended to then migrate south into southern Australian and New Zealand waters, according to Waldie. But one nester that arrived in June headed east. 

"Aunty June," as she was named, went straight across the Pacific and ended up in feeding grounds just off the coast of Baja California in Mexico. Waldie hopes further research will confirm whether mid-year nesters like Aunty June commonly take this eastern migration route, while peak season nesters like Uke Sasakolo head south.

"We call them all the Western Pacific nesters, but we might find that these nesting subpopulations are heading to completely different foraging areas," he said. 

Name: Mary River turtle (Elusor macrurus)

Where it lives: Mary /Moonaboola River, Queensland, Australia

What it eats: Mostly aquatic plants, but sometimes seeds, fruits and insect larvae

Why it's awesome: This turtle has a distinctive, punk-like appearance, thanks to green algae growing from its head and body that helps it hide from predators in its aquatic home. It also has two long, fleshy protrusions called barbels sticking out from its chin that help it sense its surroundings. 

In addition to its unusual appearance, the Mary River turtle also has a neat trick up its sleeve — or rather, its butt. 

"It can spend days at a time submerged, managing to 'breathe' underwater — a feat achieved by very few reptiles — through specialised organs inside its cloaca [an orifice found mostly in non-mammalian vertebrates for intestinal, urinary and genital tracts]," Rikki Gumbs, a researcher at the EDGE of Existence programme, a conservation initiative focusing on unique and overlooked species, told Live Science in an email.

While some freshwater turtles use their skin for aquatic respiration, using cloacal glands allows them to be submerged for longer. In the case of the Mary River turtle, this can be for up to 72 hours. 

Related: Can turtles really breathe through their butts?

The glands — called cloacal bursae — are covered with papillae, which are small structures lining the walls of the bursae. Oxygen in the water diffuses across the papillae and into the turtle's bloodstream. 

The Mary River turtle is also unique: No other turtle is closely related to it. "It is the only surviving species in its genus," Gumbs said. "It is thought the ancestors of the Mary River turtle diverged from all other living turtle lineages more than 18 million years ago — several million years before our ancestors and those of the orangutan parted ways."

Despite being prolific in the pet trade for decades in the 1960s and 1970s, its distribution in the wild was a mystery to scientists until they were finally found in the wild and formally described as a species in 1994. 

The world's oldest tortoise has turned 191 years old, extending his title of the oldest living land animal by another year. 

The Seychelles giant tortoise (Aldabrachelys gigantea hololissa), known as Jonathan, has lived on the remote south Atlantic Island of Saint Helena since 1882 after he was gifted to the governor at the time. 

Estimated to have been born in 1832, his age is a conservative estimate as he was fully mature — meaning he was at least 50 years old — when he arrived, meaning he could be even older. His assumed age was supported when an old photograph taken between 1882 and 1886 was discovered showing Jonathan grazing in residency gardens of William Grey-Wilson, the Overseas British territory Governor of St. Helena at the time. 

He was granted an official birthday — Dec. 4, 1932 — by Nigel Phillips, the governor of St. Helena, in November last year, according to the Guardian.

Jonathan holds two Guinness World Records (GWR), the oldest known living land animal and the oldest chelonian, an order known for having a hard outer shell such as tortoises, turtles and terrapins.  Jonathan claimed the title of world's oldest living mammal in 2021 from Tu’i Malila (c. 1777–1965), a radiated tortoise that lived to be at least 188.

Related: Tiny white tortoise baby is the 'first of its kind'

Seychelles giant tortoises have an average life expectancy of 150 years. Although Jonathan is blind with cataracts and has lost his sense of smell, St. Helena veterinarian Joe Hollins said he remained in good health — with a strong libido and healthy appetite. According to GWR, he still attempts to mate with the tortoises he lives with — Emma, who is about 55 years old, and Frederik, is 32.

“Animals are often not particularly gender-sensitive!” Hollins said. 

"Although aware of the responsibility and that, of course, he will die one day, I believe we have greatly enhanced his life expectancy," Hollins said in an interview with GWR. "We introduced once-weekly feeding of good calorific food and this has transformed him, demonstrating probable micro-deficiencies of vitamins, minerals and trace elements."

Jonathan was originally identified as an Aldabra giant tortoise (Aldabrachelys gigantea) from the Aldabra Atoll, which forms part of the Seychelles archipelago. But following an examination of his shell by zoological professionals and the Seychelles Nature Trust, scientists determined he was likely a rare Seychelles giant tortoise. 

European sailors hunted the species to near extinction. In fact, the species was deemed extinct until researchers analyzed captive specimens and found living individuals. According to IUCN’s Tortoise and Freshwater Turtle Specialist Group there are now around 80 recorded globally.

In his lifetime, Jonathan has lived through two world wars, 40 U.S. presidents and 31 St. Helena governors. Today, Jonathan peacefully roams the ground with three other giant tortoises called Emma, Fred and David.   

Water is essential for life, but with 96% of all Earth's water found in the oceans, most of it is almost entirely undrinkable by many of the species that live in it. But still life finds a way.

In this extract from the new book "The Blue Machine: How the Ocean Works" (W. W. Norton & Company, 2023), author and oceanographer Helen Czerski explains the ingenious and (at least for us humans) emotional way leatherback turtles contend with the extreme saltiness of their environment.

The cool water off Nova Scotia is a foggy turquoise, lit by diffuse sunlight above and fading into darkness below. The fog is made up of tiny fragments of drifting organic life, individually invisible but collectively cloaking every resident in fuzzy ignorance of everything more than 5 meters [16.4 feet] away. The ocean is quiet, disturbed only by an occasional breaking wave at the surface and the very distant deep hum of ship engines.

A leatherback turtle emerges from the fog and glides slowly through the bright nothingness. From nose to tail she is nearly 2 meters [6.6 feet] long, a solid, mottled grey oval with huge flippers and a snub nose. She has travelled nearly 4,000 kilometers [2,500 miles] from her breeding ground in the Caribbean, and she is hungry.

At a molecular level, the turtle isn't too different from us. The average salinity of her body is around a third that of seawater, and her reptilian kidneys can't produce urine that has a higher salt concentration than her blood. Her body is a neat package of low-salinity life, and her cells will fail if her insides come anywhere near the salinity of the water in which she swims. Her leathery skin is the fortress that keeps the salt out.

Related: 'Earth's civilizations are shaped by what the ocean engine does,' says oceanographer Helen Czerski

From the gloom below comes a haunting call: the long, slow cry of a humpback whale. These whales feed on fish, and those fish are much less salty than the ocean. As they're digested, their carbohydrate and fat release water, and the fish themselves contain useful water in their cells. So if a whale is careful, squeezing out the seawater that comes with each mouthful of fish before it swallows, it can get enough water from its food without taking in too much extra salt. We don't yet know for certain, but it seems likely that whales don't need to drink. The work of eliminating excess salt is largely done for them by their fishy prey, who are experts at drinking seawater and then pushing salt back out into the environment through their gills, urine and feces.

Few ocean vertebrates drink, but all of them face the challenge of keeping the water in and the salt out. The leatherback turtle is the master of this game. The turquoise gloom in which she swims is home to a living buffet of jellyfish, which is what this turtle feeds on. Every minute or two, a dark, pulsing silhouette emerges from the fog, a messy cascade of orange tendrils hanging from a colorless dome. A slight twist of her flippers, and the turtle is bearing down on the hapless mass of jelly. One snap and a puff of debris is all that remains.

But the turtle's salt budget has just taken a hit. A jellyfish is really just a small bucketful of ocean masquerading as life. It's 96% water, and most of the other 4% is salt, making the jellyfish as salty as the ocean. Less than 1% of the jellyfish is organic material and therefore useful food, and so the cost of dinner is that the turtle must accept three times as much salt as food in every mouthful.

The solution is both ingenious and (to us) heartbreaking: this gentle giant weeps as she eats. A huge proportion of her head is taken up with salt glands, organs that remove salt and push it out of her tear ducts. Leatherback tears are thick and viscous and almost twice as salty as the ocean. To keep eating without killing herself with salt, the turtle must cry around 8 liters [2 gallons] of tears every hour. But this is the cost of living in seawater. As the turtle slowly sculls onwards, fading into the turquoise, her body is sorting the ocean, scrimping and saving the nutrients, rejecting the salt, and flushing through the water.

The solution is both ingenious and (to us) heartbreaking: this gentle giant weeps as she eats. A huge proportion of her head is taken up with salt glands, organs that remove salt and push it out of her tear ducts. Leatherback tears are thick and viscous and almost twice as salty as the ocean. To keep eating without killing herself with salt, the turtle must cry around 8 liters [2 gallons] of tears every hour. But this is the cost of living in seawater. As the turtle slowly sculls onwards, fading into the turquoise, her body is sorting the ocean, scrimping and saving the nutrients, rejecting the salt, and flushing through the water.

The Yangtze giant softshell turtle (Rafetus swinhoei), the world's largest freshwater turtle and one of the most endangered species on Earth, is now essentially doomed to extinction after the last known remaining female washed up dead in Vietnam.

The female turtle, which was around 5 feet (1.5 meters) long and weighed 205 pounds (93 kilograms), was discovered dead on April 21 on the shores of Dong Mo Lake, in Hanoi's Son Tay district. The turtle likely died several days earlier, but the cause of death is still unknown, Vietnamese news site VNExpress reported.

This particular female Yangtze giant softshell turtle was just discovered in October 2020. At the time, no other female Yangtze giant softshell turtles were known to exist; the last known female of the species had died after a failed attempt at artificial insemination at Suzhou Zoo in China in April 2019.

When the dead turtle was discovered last month, conservationists had hoped that it belonged to another unknown female, and that the known female might still be alive in the lake. But experts have now confirmed this is not the case.

"It is the same individual that we've been monitoring in recent years," Tim McCormack, director of the Asian Turtle Program for Indo-Myanmar Conservation, told TIME magazine. "It's a real blow."

Related: Most of Florida's newly-hatched sea turtles are female. Why? 

There are now just two known R. swinhoei males left in existence: one in Suzhou Zoo and another that still resides in Dong Mo Lake.

Researchers had hoped that the female and male in Dong Mo Lake would eventually mate and produce a clutch of eggs. Based on its size, the female was likely several decades old, meaning it was probably sexually mature.

"It was a large female that obviously has great reproductive capacity," McCormack said. "She could have potentially laid a hundred eggs or more a year." However, the pair never mated, even though researchers built an artificial nesting beach at the lake for the female to lay her eggs if she ever needed it.

Yangtze giant softshell turtles, also known as Hoan Kiem turtles and Swinhoe's softshell turtles, were once abundant throughout the Yangtze River in China and the surrounding freshwater ecosystems, like Dong Mo Lake. However, historically, humans hunted the turtles for their meat, and they have lost most of their natural habitat, according to the Asian Turtle Program.

There is a chance that other males and females may be found in the future. After all, this female did evade detection for years. But if another female cannot be found in the wild, R. swinhoei will eventually become the latest name on a growing list of species that have been wiped out by humans.

At least a millennium ago, a giant tortoise crept through Madagascar, grazing on plants by the boatload — a bountiful diet that made it the ecosystem equivalent of mammoths and other big herbivores. And like the mammoth, this previously unknown giant tortoise is extinct, a new study finds.

The scientists discovered the species while studying the mysterious lineage of giant tortoises living on Madagascar and other islands in the western Indian Ocean. After stumbling across a single tibia (lower leg bone) of the extinct tortoise, they analyzed its nuclear and mitochondrial DNA and determined that the animal was a newfound species, which they named Astrochelys rogerbouri, according to the study, published on Jan. 11 in the journal Science Advances. The tortoise's species name honors the late Roger Bour (1947-2020), a French herpetologist and expert on western Indian Ocean giant tortoises. 

It's unclear when the newfound species went extinct, but the specimen studied appears to be about 1,000 years old. "As we get better and better technology, we are able to provide different types of data that often change our perspective," study co-author Karen Samonds, an associate professor in the Department of Biological Sciences at Northern Illinois University, told Live Science. "It's really exciting to discover a new member of the community."

Related: This may be the biggest turtle that ever lived

Volcanic islands and coralline atolls across the western Indian Ocean were once teeming with giant tortoises. Weighing up to 600 pounds (272 kilograms), these ponderous megafauna heavily influenced their ecosystems, if only through their voracious appetites. The 100,000 giant tortoises still living today on Aldabra — a verdant atoll northwest of Madagascar — consume 26 million pounds (11.8 million kg) of plant matter each year.

Most species native to that region are now extinct due to human activities, and paleontologists are still struggling to piece together the story of these bygone tortoises. But analyzing these giants' ancient DNA is providing a path forward, which, in turn, sheds light on prehistoric island life. 

"If we want to know what these island ecosystems were like originally, we need to include giant tortoises — large, extinct members of the ecosystem which took on the role often occupied by large grazing mammals," Samonds said. "And in order to understand the key role they played, we need to understand how many tortoises there were, where they lived, and how they got there."

By the time explorers began collecting giant tortoise fossils in the 17th century, Madagascar's native giant  tortoise population population had long since vanished — likely victims of colonization by the Indo-Malay people 1,000 years earlier — and their relatives plodding the Mascarene archipelago and the Granitic Seychelles were living on borrowed time. European sailors harvested the tortoises for food and "turtle oil," and all but those native to far-flung Aldabra were gone by the 19th century.

The tricky task of reconstructing their history would fall to modern paleontologists. "Tortoise remains are notoriously fragmented, and i​t's a real challenge to figure out what a tortoise looked like just from part of a shell," Samonds said. Scientists also struggled to make sense of a fossil record muddied by the tortoise trade. Had a particular specimen found in the Mascarene originated there, or was its carcass dropped off by a ship inbound from the Granitic Seychelles?

"In the end, a lot of these fossils sat in a cabinet, unused and unstudied," Samonds said. But recent technological advances in ancient DNA analysis granted Samonds and colleagues a glimpse inside the black box of tortoise evolutionary history. "It's thrilling that we now have this technology and can use ancient DNA to put these broken fossil pieces to good use."

For the study, Samonds and colleagues generated nearly complete mitochondrial genomes from several tortoise fossils, some of which were hundreds of years old. By combining these sequences with prior data on tortoise lineage and radiocarbon dating, the team was able to describe how giant tortoises migrated to various Indian Ocean islands. 

The extinct Mascarene Cylindraspis lineage, for instance, appears to have left Africa in the late Eocene, more than 33 million years ago, and taken up residence on the now-sunken Réunion volcanic hotspot. From there, the species spread around local islands, resulting in the divergence of five Mascarene tortoise species between 4 million and 27 million years ago.

Samonds hopes future paleontological studies will follow the present work's example and benefit from incorporating ancient DNA analyses into more conventional methodologies. 

"Including ancient DNA allowed us to examine how many tortoise species there were and what their relationships were to each other. It also helped us appreciate the original diversity of tortoises on these islands," Samonds said. "We couldn't have explored these topics before." 

Almost all sea turtle hatchlings are emerging from their eggs as females on some Florida beaches because of heat waves exacerbated by climate change, Reuters reported on Aug. 2.

Five different sea turtle species are found in Florida, including loggerhead turtles (Caretta caretta) and green turtles (Chelonia mydas), according to the Florida Fish and Wildlife Conservation Commission. Bette Zirkelbach, manager of the Turtle Hospital in the Florida Keys, told Reuters that scientists haven't found any male sea turtles for the past four years. So, what's going on? 

Temperature plays a major role in determining the sex of developing sea turtles. Unlike humans, whose sex determination is largely controlled by the X and Y sex chromosomes, turtle's sex ratios are determined by the temperature at which their eggs are incubated. Higher temperatures at incubation produce more females.

Climate change raises the temperature of nesting sands, causing the sex ratios of turtles to skew toward females, according to the National Oceanic and Atmospheric Administration (NOAA). Introducing too many females and not enough males into the turtle populations could reduce the animals' ability to reproduce when the turtles reach adulthood, increasing their risk of local extinction.

Related: Wildfires blaze in London during record heatwave

The strange sex ratio phenomenon isn't just affecting Florida. A 2018 study published in the journal Current Biology found that green sea turtles had a 99% female sex bias on warmer, northern Great Barrier Reef nesting beaches and a 65% to 69% female sex bias on cooler, southern beaches Down Under. 

While the skewed sex ratio could be damaging for sea turtles, having more females than males isn't necessarily all that unnatural. Sea turtle nests that are 90% female aren't uncommon and only a few males may be needed in a population to fertilize eggs, Insider reported. However, there wouldn't be any fertilization if all males disappeared. 

The temperature threshold for determining the sex of sea turtles is 81.9 degrees Fahrenheit (27.7 degrees Celsius), according to NOAA. Turtles incubated below 81.9 F hatch male and turtles incubated above 81.9 F hatch female, while fluctuating temperatures above and below this threshold produce a mix of males and females.

The process is called temperature-dependent sex determination and it affects a variety of animals, including crocodiles, many fish and some lizards. Scientists aren't certain, but they have theories as to why some animals have their sex determined this way and others don't.

"Our best guess is that temperature-dependent sex determination originated because reptiles do not have parental care and the eggs are in close interaction with the environment," Diego Cortez, a biologist at the National Autonomous University of Mexico in Mexico City, told Live Science in 2021. "We also know that elevated incubation temperatures speed up the development of embryos. So, the sex that is linked to higher incubation temperatures will hatch earlier." 

Temperature-dependent sex determination may also allow mothers to control the sex of their offspring, such as by laying eggs in cooler or warmer spots, if there is a need for more males or more females within that animal's population and species, Live Science previously reported. 

A 2020 study of loggerhead turtles published in the journal Climatic Change highlighted other problems that can arise with increased incubation temperatures. In Cabo Verde (also called Cape Verde), a country of islands in the Atlantic Ocean, the researchers found that 33% more embryos perished when incubation temperatures reached 90.1 F (32.3 C) than when incubation temperatures hovered around 85.5 F (29.7 C). The researchers also found that hatchlings incubated at high temperatures were smaller in size and more likely to be killed by crabs on their way to the ocean. 

In other words, hot temperatures can be lethal for developing turtles and reduce their survival chances when they do hatch. 

Originally published on Live Science.

Everyone knows that most mammals breathe through the mouth and nose. Frogs, meanwhile, can breathe through their skin. But what about turtles? How do these hard-shelled critters get oxygen?

You may have heard a strange rumor that turtles can breathe through their butts. But is this true?

Technically, turtles do not breathe through their derrières. That's because turtles don't really have "butts"; instead, they have a multipurpose opening known as a cloaca, which is used for sexual reproduction and egg laying as well as for expelling waste. However, they do engage in a process called cloacal respiration, which could, in a less technical sense, be interpreted as "butt breathing." 

During cloacal respiration, turtles pump water through their cloacal openings and into two sac-like organs known as bursae, which act sort of like aquatic lungs, Craig Franklin, a wildlife physiologist at The University of Queensland in Australia who has extensively studied cloacal respiration, told Live Science. Oxygen in the water then diffuses across the papillae, small structures that line the walls of the bursae, and into the turtle's bloodstream. 

 Related: Why do turtles live so long? 

However, cloacal respiration is very inefficient compared with normal aerobic respiration ,and all turtles also have the capacity to breathe air with their lungs much more easily. As a result, cloacal respiration is seen only in a small number of freshwater species that rely on this unorthodox method to overcome challenges they face in unique environments where it is hard to breathe air, such as fast-flowing rivers or frozen ponds.

Cloacal champions 

The main turtle group that has truly mastered cloacal respiration is river turtles. Globally, there are around a dozen river turtles that can properly utilize cloacal respiration, around half of which live in rivers in Australia; these include the Mary River turtle (Elusor macrurus) and the white-throated snapping turtle (Elseya albagula), Franklin said. 

However, some species of river turtle are much better at cloacal respiration than others. The undisputed champion is the Fitzroy River turtle (Rheodytes leukops) from Australia, which can derive 100% of its energy through cloacal respiration. "This allows them to potentially remain underwater indefinitely," Franklin said. 

But for all other species, cloacal respiration only extends the amount of time they can stay underwater until they must resurface for air. "For example, instead of diving underwater for 15 minutes [while holding their breath], they can remain underwater for several hours," he said.

The ability to stay underwater for extended periods of time is extremely useful for river turtles because going to the surface can be hard work. "For a turtle that lives in fast-flowing water, going to the surface to breathe represents a bit of an issue because you could get swept away," Franklin said. Staying close to the riverbed also makes it easier to avoid predators such as crocodiles, he added.

Avoiding predators is particularly important for baby turtles, which can be targeted by birds and large fish. "The greatest risk of predation for a hatching turtle is swimming through the water column to the surface," Franklin said. As a result, juveniles are normally much better at cloacal respiration than adults, which allows them to spend more time near the riverbed until they are big enough to start venturing more frequently to the surface. Therefore, it is possible that additional river turtle species are also capable of cloacal respiration as juveniles but then lose this ability in later life, Franklin said.

However, cloacal respiration is much less efficient than aerobic respiration because pumping water into the bursae requires a lot of energy, which reduces the net gain of energy the turtles receive. "When we breathe air, there's virtually no energy required" because gases are light and flow freely in and out of our lungs, Franklin said. "But imagine trying to breathe a viscous liquid back and forth." Water also has around 200 times less oxygen than an equal volume of air, so turtles have to pump more of it to gain the same amount of oxygen, he added. 

Related: How do animals breathe underwater?

There is also another cost to cloacal respiration. When oxygen diffuses across the skin of the bursae and into the bloodstream, sodium and chloride ions (charged particles) inside papillae, which are vital to the functioning of cells, diffuse in the opposite direction into the water, which stops the cells from functioning properly. To counteract this, the turtles have evolved special pumps that suck the lost ions back into the cells to maintain normal ion levels. This process, known as osmoregulation, requires additional energy, thus further reducing the net gain of energy from cloacal respiration. 

Stuck under ice 

There are also around six or seven species of hibernating freshwater turtles across North America that are capable of a more limited form of cloacal respiration. These species, such as Blanding's turtle (Emydoidea blandingii), spend months trapped beneath layers of ice that cover ponds during the winter. Some of these turtles are under the ice for more than 100 days without being able to take a single breath of air, Jackie Litzgus, a wildlife ecologist at Laurentian University in Ontario, told Live Science. Instead, these turtles can also take up oxygen through bursae, as well as by gargling water in their throats, which is known as buccal pumping, Litzgus said. 

However, the cloacal respiration displayed by hibernating turtles is much less complex than what the river turtles are capable of, Franklin said. Instead of actively pumping water into their bursae like their river-dwelling relatives do, the hibernating turtles take up oxygen that passively diffuses across the skin in the bursae. This process is more like cutaneous respiration — when oxygen diffuses through an animal's skin, which happens in amphibians, reptiles and, in a limited capacity, some mammals, including humans. 

The hibernating turtles get away with this passive form of cloacal respiration because they have a greatly reduced metabolic rate, which means they need less energy and, therefore, less oxygen. While they are under the ice, these turtles do not move around very much, keep their body temperature close to freezing and can switch to anaerobic respiration — a last resort for creating energy without oxygen — when they are low on oxygen, Litzgus said. 

Originally published on Live Science.

Death comes for all, but aging doesn’t — at least for some animal species

Two new studies published Thursday (June 23) in the journal Science found that turtles and tortoises have remarkably slow rates of aging. In captivity, without the stress of finding food and avoiding predators, some may not age at all.

"That is super fascinating," said one study's lead author Rita de Silva, who conducted the research while at the University of Southern Denmark and who is now a biologist at the Universidade do Porto in Portugal. What makes it even more interesting is that modern humans have yet to unlock this benefit, even though we inhabit a world with fewer challenges to our day-to-day survival than the habitats of our early ancestors. 

"As modern humans, we tend to live in really good conditions, so the environment for us would be close to ideal [as well]," de Silva told Live Science. "And still, we cannot lower our aging rate."

How the turtles avoid aging is a bit of a mystery, but the secret may lie in their shells.

 Aging and death 

Understanding this turtles' anti-aging superpower first requires a quick tutorial on the mind-bending notion that while death is inevitable, aging might not be. There are a couple of ways to think about age. One is longevity, or the maximum lifespan of a species. Scientists often define longevity as the age at which a large proportion, say 95%, of adults in a population are dead. For humans, that pegs longevity at around 100 years.

The other way to think about aging is senescence. Senescence is the weakening of an organism as it ages. It’s easy to see this in humans; with age, immune systems falter, bones become brittle, energy flags. What’s more, death becomes statistically more likely with each year of age. For example, according to Social Security Administration actuarial tables, a 50-year-old man in the United States has a 0.48% chance of dying within the next year. An 80-year-old man has a 5.6% chance of death within a year. For a centenarian man, there’s a nearly 35% chance that he won’t ring in the next year.

Related: Why do turtles live so long?

The new research reveals that this accumulation of risk is much, much slower in turtles, and in some cases may not exist at all. In other words, in some species, age doesn’t increase the risk of death. Eventually, all turtles will die, because if there’s even a 1% chance of death each year, it’s inevitable that the age-defying reptile’s number will eventually come up. But that chance of death may be the same whether the turtle is 5 or 25 years old — or in the cases of some long-lived species, perhaps even 125 years old.  

Scientists have long noted that turtles and tortoises can live extremely long lives. This year, for instance, a Seychelles giant tortoise (Aldabrachelys gigantea hololissa) named Jonathan turned 190, making him the oldest tortoise ever and the oldest recorded land animal. Research on turtle biology suggests that turtles and tortoises are able to quickly kill off damaged cells and that they are resistant to DNA damage that accumulates over time as cells divide; this protects individuals even as they enter extreme old age, Live Science previously reported.

The evolution of aging 

The big question, evolutionarily speaking, is how turtles accumulated these incredible anti-aging powers — and why the rest of us are stuck growing old. In the two new studies, researchers investigated the question in both wild and captive turtle and tortoise populations. 

The study led by de Silva looked at 52 species in captivity whose records were available in the Species360 Zoological Information Management System, software used by zoos to track data about animal husbandry. They found that about 75% of species showed zero or negligible aging rates. In some cases, there was a wide range of uncertainty around the rate of a species’ aging, but in others, the numbers were consistent around zero, meaning that these species probably age very slowly or not at all. Some of these consistent negligible agers included the Greek tortoise (Testudo graeca) and the black marsh turtle (Siebenrockiella crassicollis). The Aldabra giant tortoise (Aldabrachelys gigantea) showed a negligible aging rate and a particularly long average lifespan of 60 years or more in captivity. The Galápagos tortoise (Chelonoidis niger), one of the species studied by scientist Charles Darwin on his voyage to the islands of the same name in 1835, also lived 60 years or more on average.

The second study, conducted by a different research group, looked at aging in wild populations. One hypothesis for why turtles age slowly has long been that because they are cold-blooded, they don’t have to spend energy on maintaining their body temperature, perhaps allowing them to direct energy toward cellular repair. Northeastern Illinois University biologist and lead author Beth Reinke, co-author and Pennsylvania State wildlife population ecologist David Miller, and colleagues wanted to test this idea by comparing cold-blooded animals’ aging rates to warm-blooded animals’ aging rates, controlling for factors such as body size.

To do this, they had to pull together data from multiple scientists across the world who mark or tag animals within a wild population and then go back year after year to see if they can recapture those animals. These long-term field studies are one of the few ways to learn about animal longevity and demographics in the wild.

"I'm just so in awe that we were able to get so many researchers willing to contribute their data that they've sweated hours for in the field," Reinke told Live Science.

To their surprise, the researchers found that cold-blooded animals didn’t age slower than warm-blooded animals did; instead, the cold-blooded creatures displayed a much broader range of aging's effects, with some aging more quickly than similarly sized warm-blooded animals, and some aging more slowly. At least one species in each of four groups (frogs and toads, crocodilians, squamate lizards, turtles) showed negligible rates of aging. However, as in de Silva and colleague’s study, the turtles stood out.

"What we found is there are some really consistent patterns in turtles, which is that they live a long time, and they age really slowly," Miller told Live Science.

Because cold-bloodedness couldn’t explain this slow aging, the researchers tested some other possible factors that might explain why some species age fast and others age slowly. They looked at the average local temperatures in each species’ range, but found varying patterns: Hotter climates increased the rate of aging in reptiles, but decreased it in amphibians. They also found that longevity was linked to later sexual maturity, indicating a slower life pace for long-lived cold-blooded creatures.

How to die without aging 

But one of the most interesting findings was that the slowest-aging cold-blooded creatures were also those that had the most robust defenses to protect them from predators. In particular, physical protection like shells was associated with low aging rates.

Shells keep turtles from being eaten, meaning that their mortality rates from outside sources are lower than animals without such protection. (Imagine the likelihood of a young box turtle surviving an attack from a fox, compared with the chances of a young bunny.) This low mortality rate across all ages means turtles are likely to survive long enough to take advantage of their cellular protections against aging, Miller said.

"If a lot of animals get eaten or die by disease. not many survive long enough for there to be any benefit from the sort of cellular processes that slow aging down," Miller said. Protective features may allow animals to live long enough for evolution to act on anti-aging protections, in other words. 

There are potential evolutionary parallels with humans, Miller said, many of whom today live in cushy conditions with easy access to food and shelter – not unlike captive turtles. Turtles and tortoises may seem enviable in their slow aging, but humans are actually not slouches in the longevity department, Miller said. Humans age quicker than the average turtle, but a lot slower than many other species.

The biology of turtles and tortoises could help unlock anti-senescence secrets for humans, but a lot more research is required to get there, Reinke said. More work is needed to understand the evolution of aging in other animals, too. For example, there isn’t much data on extremely long-lived species, especially looking at whether or not aging rates accelerate at some point in animals that live very long lives. Jonathan the tortoise, for example, is blind, can’t smell, and must be hand-fed, University of Alabama, Birmingham biologist Steven Austad and University of Southern California aging researcher Caleb Finch wrote in an editorial accompanying the two studies.

"Even if many of these fascinating species lack significantly increasing mortality with age," Austad and Finch wrote, "some clearly incur infirmities of aging."

Originally published on Live Science  

An extremely rare white tortoise baby has just been revealed to the world for the very first time. The tiny, red-eyed reptile has pigmentless skin and a pale shell, caused by a genetic disorder known as albinism. Zoo keepers say the odds of an albino tortoise are 1 in 100,000.  

The white tortoise is one of two Galápagos giant tortoises (Chelonoidis niger) that recently hatched at Tropiquarium, a zoo in Servion, Switzerland. The pair of eggs were laid by a 220-pound (100 kilograms) female on Feb. 11; the albino baby hatched on May 1 and its darker sibling emerged on May 5. The baby tortoises each weighed just 1.8 ounces (50 grams) at birth and were initially hand-reared by zookeepers in incubators, before rejoining their mother at the zoo on June 3, according to Reuters.

"We were surprised to discover an albino baby," zoo staff wrote in a statement. "This is the first time in the world that an albino Galápagos tortoise has been born and kept in captivity," and there are no documented cases in the wild, they added. The team also speculated that the birth of a white tortoise could be as much as five times rarer than the birth of an albino human, which is around 1 in 20,000 people, according to the National Organization for Albinism and Hypopigmentation, a nonprofit organization that provides information and resources about albinism to people in the U.S. and Canada.

Albino animals are unable to produce a skin pigment known as melanin, which is what gives color to skin, hair, eyes and feathers — and in this case, the tortoise's shell. Albino animals often appear to have red eyes because their eyes have no pigment, so they appear the same color as the blood vessels underneath the eyes' surface. 

Related: 7 oddly colored animals that caught our eye in 2021 

Albinism is a genetic condition, which means it is passed down from parents to offspring. However, it is a recessive trait, so both parents need to possess and pass on a copy of the gene. Because the parents usually only have one copy of the albino gene (unless they are also albino), they appear with the animal’s typical colors.

It is unclear how long the albino hatchling might survive. Galápagos giant tortoises are the largest tortoises on Earth and can live for more than 100 years in the wild. However, albinism can make animals more susceptible to damage from the sun's ultraviolet rays and prone to other health complications, such as reduced vision and hearing difficulties. It also makes animals that are normally darker colored more visible to predators. This means animals with albinism often don’t survive for very long and die before they can pass on their genes — which explains why the condition is so rare. But if they are cared for properly in captivity they can live relatively healthy lives. 

Breeding Galápagos giant tortoises in captivity can be challenging.  The mating rituals of these enormous reptiles can be quite aggressive: Males repeatedly ram females' shells with their own and sometimes bite females' legs, before mounting them. The males also produce very loud and deep moaning sounds during sex, which helped inspire the roaring sounds of dragons from HBO's hit fantasy show "Game of Thrones."

Like a majority of reptiles, Galápagos giant tortoises’ gender is determined by the temperature at which the eggs are incubated. In this species, warmer conditions cause the tortoises to become female, and lower temperatures produce males, according to the San Diego Zoo. The genders of the new pair of hatchlings are uncertain because there are no physical differences between males and females at this age, according to Reuters.  

Zoos are the only places where Galápagos giant tortoise hatchlings — albino or not — can be observed. In the wild, hatchlings seem to "disappear" until they are around five years old. Researchers aren't exactly sure where the babies go, but scientists suspect that the juvenile tortoises spend their first few years hiding in forest undergrowth to avoid their only natural predator: Galápagos hawks (Buteo galapagoensis), according to the Zoological Society of London (ZSL). Nobody is sure how the tiny tortoises spend these so-called lost years, but when they reemerge they are too large to be carried off by the predatory birds, ZSL says. 

Captive breeding in zoos is a very important tool for conserving these massive tortoises, which have become scarce in the wild. Wild tortoise populations in Galápagos were severely impacted by early European explorers, whalers and naval crews, who hunted tortoises as a source of oil and food for long journeys across the seas. Scientists think there were once around 200,000 giant tortoises in the Galápagos Islands, which are named after the tortoises (the word "Galápagos" comes from an archaic Spanish word for "tortoise"), but there are now only around 15,000, according to the Galápagos Islands Trust. 

Experts also believe that warmer temperatures caused by climate change could be skewing the gender ratio among tortoise hatchlings, which could impact future reproduction in the wild. (If more babies are born female, there will be fewer males to mate with, reducing genetic diversity in wild populations.)  

Originally published on Live Science.

More than one-fifth of reptile species across the globe are threatened with extinction, with those living in forests found to be in far greater danger than those inhabiting arid areas, a new study reports.

In the most comprehensive extinction-risk assessment ever carried out on reptiles, researchers discovered that as many as 21.1% of all known species were at risk.

"It's just overwhelming the number of species that we see as being threatened," said study co-author Neil Cox. The researchers published their findings on April 27 in the journal Nature.

Prior to this new research, there had been no formal attempt to determine how many reptiles were at risk of extinction. Instead, conservationists relied on the International Union for Conservation of Nature's (IUCN) Red List of Threatened Species, which provides the risk status of birds, mammals and amphibians.

By using the Red List's criteria, the study researchers discovered 1,829 out of 10,196 reptile species were vulnerable, endangered or critically endangered — a total of 21.1% of the known species.

They also found that 57.9% of turtles and 50% of crocodiles are threatened; overall, 40.7% of amphibians, 25.4% of mammals and 13.6% of birds are considered threatened by the IUCN, according to the Red List.

The global study was carried out over 15 years with the help of 961 researchers representing 24 countries across six continents.

For the study, researchers assessed preexisting surveys and datasets of turtles, crocodiles, lizards, snakes and tuatara in Africa, the Americas, Asia, Australia, the Caribbean, Europe and Oceania. Tuatara are endemic to New Zealand and are considered to be the last survivors of an order of reptiles that can be "traced back to the Triassic period, according to the New Zealand Department of Conservation.

The authors said reptiles were being threatened globally by agriculture, logging, urban development and invasive species. This would explain why the researchers found that 30% of reptiles living in forests were at risk of extinction compared to 14% of reptiles living in arid habitats, the authors said.

The researchers also found that threatened reptiles were concentrated in Southeast Asia, West Africa, northern Madagascar, the Northern Andes and the Caribbean — a finding that will enable conservationists to concentrate their efforts in places with the greatest need.

The study authors also narrowed down the primary threats for different groups of reptiles. For instance, lizards that live on islands are threatened by predators that have been introduced there by people. By comparison hunting and poaching are the main threats to turtles and crocodiles, the IUCN said.

How climate change is threatening reptiles is not known for certain due to a lack of long-term studies, the authors said. However, they wrote in the paper that climate change is a "looming threat" because it reduces the window when temperatures are right for the cold-blooded animals to forage, and it can also alter the sex ratios of offspring in species where that is determined by temperature.

"Reptiles are not often used to inspire conservation action, but they are fascinating creatures and serve indispensable roles in ecosystems across the planet," Sean T. O’Brien, President and CEO of NatureServe, which led the study in collaboration with the IUCN and Conservation International, said in a statement. We all benefit from their role in controlling pest species and serving as prey to birds and other animals."

A 70 million-year-old fossil unearthed in Transylvania is a newfound species of freshwater turtle that likely survived the extinction event that wiped out the nonavian dinosaurs.  

Researchers initially found the reptilian fossil at a site called Haţeg Basin in Romania in the 1990s. The remains include near-complete sections of the turtle's carapace (upper shell) and plastron (lower shell), as well as a bone from one of its arms and another from its pelvis. Based on these body parts, the researchers estimated that the turtle would have had a body length of around 7.5 inches (19 centimeters), they reported in a new study. The team named the new species Dortoka vremiri in honor of Mátyás Vremir, an expert in Cretaceous vertebrates who died in 2020.

D. vremiri belongs to a group of turtles known as side-necked turtles, of which there are 16 living species found in South America, Africa and Australia. Fossils of a similar species that likely descended from D. vremiri date back to around 57 million years ago, which suggests that D. vremiri survived the end-Cretaceous extinction event that wiped out around 75% of all life on Earth. 

Related: 10 coolest non-dinosaur fossils unearthed in 2021 

"Intriguingly, members of the same family of turtles did not survive this extinction event in western Europe," lead author Felix Augustin, a doctoral student at the University of Tübingen in Germany, said in a statement. The newfound species' geographic range and freshwater habitat likely helped it survive when its relatives and most terrestrial species could not, the researchers said.

The researchers think that, during the Cretaceous period (145 million to 66 million years ago), the Haţeg Basin was likely a separate island that later merged with Eastern Europe. This island could have somewhat isolated D. vremiri from the ecological destruction caused by the falling asteroid, Augustin said in the statement. 

However, a previously discovered ancient tortoise, Kallokibotion bajazidi, which experts believe shared the island with D. vremiri during the late Cretaceous, did go extinct along with the dinosaurs. "This fits a previously observed pattern from North American faunas where terrestrial vertebrates were notably more impacted by the end-Cretaceous extinction than freshwater species," co-author Zoltan Csiki-Sava, a paleontologist at the University of Bucharest in Romania, said in the statement. 

Freshwater food chains rely on decaying organic matter in the water, which would have continued to remain abundant, or potentially even increased, during the end-Cretaceous extinction event. However, the base of the terrestrial food web is plants, and around half of plant species on Earth were killed off by either massive wildfires set off by the crash or reduced sunlight from a period of global dimming that followed the initial impact, and limited their ability to photosynthesize. This difference in food availability is what allowed D. vremiri to outlive its terrestrial counterpart, the researchers said in the statement.

In May 2021, paleontologists in Madagascar discovered another Cretaceous freshwater side-necked turtle that they also suspect survived the mass extinction event before later becoming extinct, Live Science previously reported.  

Evidence of freshwater ecosystems being more resilient than terrestrial ecosystems to extinction events remains rare, but findings like those in the new study could provide clues as to how freshwater species could fare when faced with upcoming ecological crisis caused by human activity such as climate change, senior author Márton Rabi said in the statement. 

The study was published online Feb. 8 in the Journal of Systematic Palaeontology.

Originally published on Live Science.

A 190-year-old tortoise named Jonathan has become the oldest tortoise ever, adding to his list of age-defying accolades. 

Jonathan is estimated to have been born in 1832, which means he turned, or turns, 190 years old in 2022, Guinness World Records announced on Jan. 12. To put that into context, Jonathan was born before Queen Victoria ascended the British throne in 1837.

The elderly Seychelles giant tortoise (Aldabrachelys gigantea hololissa) was already the Guinness World Record holder for the oldest living land animal, but now he is officially the oldest turtle or tortoise ever recorded. He beat previous record-holder Tu'i Malila, a radiated tortoise (Astrochelys radiata) that lived to be at least 188 years old before dying in 1965. 

Jonathan lives on St. Helena, an island in the South Atlantic Ocean. "He is a local icon, symbolic of persistence in the face of change," Joe Hollins, Jonathan's veterinarian, told Guinness World Records. 

Related: The longest-living animals on Earth

Jonathan arrived on St. Helena in 1882 when he was about 50 years old, according to the British Museum in London. A photograph of Jonathan dated between 1882 and 1886 shows him fully grown, which suggests he was at least 50 years old when it was taken, so he could be older than 190 years today. 

In his twilight years, Jonathan is blind and can't smell but still grazes on the grounds of the governor of St. Helena's residence where he lives with fellow giant tortoises David, Emma and Fred. He is fed by hand once a week to ensure he gets enough calories. His favorite foods include cabbage, cucumber and carrots, according to Guinness World Records. As well as eating, Jonathan's main interests include sleeping and mating. 

"In spite of his age, Jonathan still has good libido and is seen frequently to mate with Emma and sometimes Fred — animals are often not particularly gender-sensitive!" Hollins told Guinness World Records. 

Scientists don't yet understand all of the processes that allow tortoises like Jonathan to live for so long. Giant tortoises quickly kill off damaged cells in a process called apoptosis, which may help protect them against damage to cells that normally deteriorate as we age, Live Science previously reported. 

Jonathan's longevity may be unmatched on land, but there are longer living animals in water. For example, Greenland sharks (Somniosus microcephalus) have an estimated maximum life span of at least 272 years, and Hydra, a group of small jellyfish-like invertebrates, continually regenerate their cells and don't seem to age at all.

Originally published on Live Science.

"Nature is healing" is a popular refrain we've heard time and again over the last two years. Sure … tell that to the baby bird who had its head bitten off by a rampaging tortoise in the Seychelles, or the fish in Texas who woke up to find its tongue replaced by a bloodthirsty parasite.

Nature is, and always has been, brutal, awesome, epic and heavy as a black hole's empty heart. In 2021, things were no different. Here are 9 of our favorite times when nature was totally metal this year.

1. The fish with parasitic lice for a tongue

In the end, all things die and become bug food. Sometimes, death is not a prerequisite.

Take this unfortunate Atlantic croaker caught off the coast of Texas just before Halloween. When fishers cracked the croaker's mouth open, they found that its tongue had been replaced by the parasitic isopod (see: armored sea bug from hell) known as the tongue-eating louse. Females of this species enjoy the cheery job of infiltrating a fish's mouth, latching onto the blood vessels below its tongue, then sucking the organ dry until it rots away. The louse gets a cozy new home, where she continues to feed on blood and mucus for the duration of the fish's life — which, surprisingly, isn't much impacted by the parasitic squatter in its mouth, Live Science previously reported. Don't you just love when animals get along?

Read more: 'Tongue-eating' lice invade fish's mouth in this year's creepiest Halloween photo

2. The ancient T-rex fight club

With banana-sized teeth and a bite force that could crush a car, T. rex and its cousins were arguably the most brutal animals that ever lived. What did these killers do when there was no prey around to slaughter? Why, they fought each other in back-alley tyrannosaur fight clubs, according to new research in the journal Paleobiology.

In their study, researchers analyzed 202 tyrannosaur skulls and jaws that had a total of 324 scars. The team found that none of the young tyrannosaurs had any bite marks, while about half of the older specimens were slashed with scars. These seasoned fighters "were likely posturing and sizing each other up, then trying to grab each other's heads between their jaws," lead study author Caleb Brown, a curator at the Royal Tyrrell Museum in Alberta, Canada, told Live Science at the time. The tyrannosaur-on-tyrannosaur fights could have been over territory, mates, meals or just status, the researchers added.

Read more: Tyrannosaurs bit each other's faces in dino fight clubs

3. The great Jersey 'worm tornado'

We're not sure if "wormnado" is an official sign of the apocalypse, but it's halfway to a Biblical plague, at the very least. Residents of a New Jersey town encountered this freaky scene when on the sidewalk after a spring rain in late March. Hundreds of words spread across the sidewalk, with even more contorted into a bizarre spiral shape where the pavement met the grass. What is the meaning of this horror? Experts told Live Science that the worms likely fled the soil en masse after heavy rains the night before, seeking the air above (worms breathe through their skin). The spiral pattern may just be a coincidence, or could indicate the direction of the water flow, one researcher said — but no one could decode this dark omen for sure.

Read more: Bizarre 'worm tornado' in New Jersey has scientists baffled

4. The 'space hurricane' over the North Pole

Unphased by the worm tornado? Then look north, friends, to the 600-mile-wide (1,000 kilometers) hurricane of plasma that whirled over Earth's magnetic North Pole for nearly 8 hours. The towering vortex was invisible to the naked eye, but appeared clear as day on four weather satellites that passed by. Like terrestrial hurricanes, the plasma cyclone had a quiet "eye," a funnel and counterclockwise-spinning spiral arms — but, instead of raining water, the vortex showered the upper atmosphere with crackling electrons.

Though this so-called "space hurricane" raged in 2014, scientists just got around to studying it this year, publishing their results in the Feb. 22 edition of the journal Nature Communications. The team hypothesized that the hurricane resulted from a complex interaction between incoming solar wind and the magnetic field over the North Pole. Scientists didn't even know space hurricanes existed before this year; Now, researchers suspect they may be common phenomena on planets with a magnetic shield and plasma in its atmosphere. Something to keep in mind if you're planning any interplanetary travel this holiday.

Read more: First-ever 'space hurricane' detected over the North Pole

5. The bird-hunting assassin tortoise

Tortoises are cute, wrinkly grandma reptiles without a vicious bone in their bodies, right? Wrong — especially if you're a baby bird.

Shocking footage shared in the journal Current Biology in August shows, for the first time ever, a killer tortoise on the hunt. In the video, a female Seychelles giant tortoise lumbers across a log in the Seychelles archipelago, determinedly advancing toward a young tern. The bird pecks back as the tortoise barrels down, but the reptile is undeterred; after a 90-second chase (that's breakneck speed, in tortoise time) the wrinkly hunter clamps its serrated beak around the bird's head, killing it instantly.

This is the first video evidence of a tortoise hunting another animal — but it's almost certainly not the tortoise hunter's first kill, the study authors said. This reptile clearly had experience hunting terns on logs; that makes this tortoise a literal cold-blooded killer.

Read more: Tortoise hunts baby bird in slow-motion, crushes its skull in shocking video

6. The cheetahs that fought a river (and won)

It turns out that cheetahs are even more metal than we thought. Well known as the world's fastest sprinters, these great cats are also powerful swimmers, undeterred by raging rivers. A photograph taken near the Talek River in Kenya shows as much, with four determined-looking cheetahs paddling like crazy against the choppy waves.

The crossing was no picnic. According to photographer Buddhilini de Soyza, the river's current dragged the cheetahs about 330 feet (100 meters) downstream — and pulled one of the cats underwater for nearly 20 seconds — but ultimately, they all made it across. The purpose of this death-defying journey? Either the cats knew they were having their picture taken and wanted to give us a new reason to fear them — or, more likely, they were looking for food. De Soyza said he saw the pack successfully hunt a wildebeest on the same side of the river a few days later. (This photo was a highly commended entry in the 2021 Wildlife Photographer of the Year competition).

Read more: Cheetahs battle raging river in stunning photo. Did they survive?

7. The organ-swallowing murder snakes

Snakes frequently make these little lists of ours, probably because they have simplified the carnivorous body plan to a fine art; snakes are basically just murderous mouths attached to hungry stomachs — all killer, no filler.

This year's recipient of the Most Metal Serpent award is the knife-toothed kukri snake of Thailand. Put one near a banded bullfrog and you'll see why. As research in the Feb. 15 issue of the journal Herpetozoa found, kukris are picky eaters who go straight for their prey's internal organs. They do this by biting a hole in the unfortunate frog's side, shoving their heads into the body cavity, then shaking the still-living frog around in a series of "death rolls," possibly in an attempt to liberate the frog's organs from its abdomen. In several encounters, the snake went on to swallow its froggy prey whole after eating its organs. Who doesn't like a little dessert?

Read more: Snakes insert their heads into living frogs' bodies to swallow their organs (because nature is horrifying)

8. The mind-control fungus that turns flies into necrophiles

Of course, some killers don't need fangs to empty their victims from the inside out. The pathogenic fungus Entomophthora muscae plays a longer game with the house flies it preys upon — first taking over the fly's mind and turning it into a living zombie, according to a study published to the preprint database bioRxiv in October. The fungus then manipulates the fly's behavior, forcing its victim to climb to an elevated place, where the fly clings on, stretches out its wings and dies — consumed by the fungus from within. Fungal spores sprout from the fly's wings and body, waiting to infect another victim.

But for female flies, the horror isn't over; researchers found that the fungus also emits an alluring scent to attract male visitors to infected female corpses. The potent scent inspires healthy males to mount the female's corpse, spreading the spores to the male, and — if all goes to plan — on to his friends and neighbors. (Leave it to a fungus to somehow be scarier than a killer snake).

Read more: Mind-controlling fungus makes male flies mate with dead, infected females

9. The goat that gored a grizzly

One of the year's most surprising animal battles occurred in the Canadian Rockies in September, when hikers discovered the body of a 154-pound (70 kilograms) female grizzly bear just off a popular trail. When Parks Canada officials investigated the bear's body, they found two stabbing wounds near the grizzly's neck and armpit. A necropsy (animal autopsy) of the bear revealed a surprising killer; the holes were an exact match for the shape and size of mountain goat horns.

According to Parks officials, the bear was probably attacking a goat, when the prey turned the tables on the predator and lashed back with its horns. Other cases of mountain goats defensively killing bears have been reported in the past, experts said, but direct evidence of these encounters is rare. So, let this incident remind any predators out there: If you mess with the goat, you'll get the horns.

Read more: Mountain goat kills grizzly bear by stabbing it with razor-sharp horns

For more totally metal coverage:

-8 times nature was totally metal in 2020

-10 times nature was totally metal in 2019

-9 times nature was totally metal in 2018

Originally published on Live Science.

Conjoined turtles with two heads and a single body have hatched at a Massachusetts wildlife center. Against all odds, the fused siblings are thriving.

The baby turtles, diamondback terrapins (Malaclemys terrapin), are "very alert" and "active," according to a recent Facebook post from the New England Wildlife Center's Cape Cod branch. "Animals with this rare condition don't always survive very long or live a good quality of life, but these two have given us reason to be optimistic."

Genetic or environmental factors that influence the embryos as they develop can cause the condition known as bicephaly, or having two heads. Living animals with bicephaly are extremely rare because many don't survive, Live Science previously reported. Some other examples include a two-headed viper discovered in Virginia, a two-headed deer found dead in Minnesota and a two-headed porpoise taken out of the North Sea.

Related: The 12 weirdest animal discoveries 

The baby turtles hatched in a protected nesting site in Barnstable, Massachusetts. The wildlife center has been taking care of them for a little over two weeks, and the turtles continue to be "bright and active," according to the Facebook post. 

The wildlife center has used X-rays to learn more about how the turtles navigate the world. It seems that they have two spines that merge further down the body and that each turtle has control of three legs.

In the first couple of days after hatching, the turtles got their nutrition from the same yolk salk. By giving the turtles a white powder that can be visualized on X-rays of the gastrointestinal (GI) tract, the researchers found that each turtle has a separate GI tract. One of the GI tracts seems a bit more developed, but both turtles are eating and digesting food. 

A deep-water swim test showed that the two siblings can coordinate swimming to the surface to breathe. The two are eating, swimming and gaining weight. "It is impossible to get inside the heads of these two, but it appears that they work together to navigate their environment," according to the post. 

The researchers hope to get the turtles a CT scan once they're a bit older to learn more about the internal organs and structures they share. "There is still so much to learn about them," the wildlife center wrote in the post.

Originally published on Live Science.

A Florida reptile dealer known as "The Lizard King" faces federal charges for illegally harvesting turtles from the wild to smuggle out of the United States and sell overseas.

The 54-year-old Michael Van Nostrand owns the reptile wholesale store Strictly Reptiles, Inc. in Hollywood, Florida. The business sells a variety of reptiles, such as turtles, snakes, lizards and baby alligators, as well as assorted species of amphibians, large spiders, scorpions and "exotic mammals," according to the store website, and Van Nostrand earned his royal title after penning his memoir "The Lizard King" in 2008, The Associated Press (AP) reported.

Documents filed in Miami federal district court show that Van Nostrand and his company established a network of so-called collectors to gather protected freshwater turtles from the wild, representatives of the U.S. Attorney's Office in the Southern District of Florida said in a statement on Oct. 5. 

Related: In photos: Tagging baby sea turtles

Van Nostrand then falsely labeled the turtles as having been bred in captivity, so that customers would not suspect that the animals had been collected illegally, according to the U.S. Attorney's Office. Collecting wild turtles for commercial sale has been banned in Florida since 2009, ABC News reported.

"Van Nostrand's co-conspirators — the 'collectors' — represented in federal export disclosure documents that the turtles were captive-bred, rather than wild-caught, which was a lie," according to the statement. Between 2017 and 2019, Van Nostrand and Strictly Reptiles trafficked hundreds of turtles, selling them in China, Japan and elsewhere. Freshwater American turtles are popular in some Asian countries as pets and as food, with some highly prized turtles selling for as much as $10,000 in auctions near Shanghai, Radio Free Asia reported in 2020.

One of the turtle species targeted by Van Nostrand was the three-striped mud turtle (Kinosternon baurii), an aquatic turtle with an oval-shaped shell and a body measuring about 4 inches (10 centimeters) long, according to the Florida Fish and Wildlife Conservation Commission (FWC). These small reptiles have large heads, usually with two yellow stripes on each side. Their brown shells are also striped, though these markings are not always visible, according to FWC.

Striped mud turtles live in natural freshwater ponds and ditches where salinity is low; if the water becomes too salty, the turtles can't survive there, FWC says.

If convicted, the so-called Lizard King could face a fine of at least $250,000 and up to five years in prison, while Strictly Reptiles could face criminal fines of up to $500,000, according to the statement. Van Nostrand was previously convicted of wildlife smuggling in 1998, and he was sentenced to eight months in prison for buying trafficked lizards and snakes, according to the AP. 

Originally published on Live Science.

In shocking new video footage, a giant tortoise creeps toward a baby bird perched on a log, slowly and steadily cornering the chick before chomping down on its tiny skull. 

The footage ends after the lifeless bird tumbles to the ground, but the researcher who captured the video reported that the tortoise swallowed the chick whole moments later. The chilling video is the first documented case of "deliberate hunting" in any tortoise species, the researchers wrote in a report published Monday (Aug. 23) in the journal Current Biology. 

This dramatic, albeit slow-motion, hunt took place on Frégate Island, part of the Seychelles archipelago in the Indian Ocean off the East African coast. The footage was recorded by Anna Zora, the island’s deputy conservation and sustainability manager, who had been surveying seabird populations in a woodland when she spotted a female Seychelles giant tortoise (Aldabrachelys gigantea) exhibiting some very strange behavior.  

Related: Survival of the grossest: 8 disgusting animal behaviors 

"There was just something odd about the way it was behaving," said senior study author Justin Gerlach, the director of biology studies at the University of Cambridge’s Peterhouse College in the U.K.

Typically, giant tortoises meander about, munching on plants as they go, and they only really walk in a purposeful manner when engaging in aggressive behavior, Gerlach said. For instance, male tortoises might make a beeline toward each other when fighting over mates. The Seychelles tortoise in Zora's video walked with similar deliberation, very unlike how a tortoise would move if engaging in casual eating behavior, Gerlach said.

Zora observed the tortoise's minutes-long approach to a juvenile lesser noddy tern (Anous tenuirostris) that was sitting on a log nearby; the flightless chick had likely fallen from a nest in the trees above. The tortoise clambered onto the log and marched toward the tern, opening its jaws wide and retracting its tongue — as is "typical for aggressive tortoise behavior," the study authors noted. The small bird pecked at the approaching tortoise in vain, while stumbling backward on the log and flapping its wings.

"It does exactly the wrong thing," Gerlach said of the bird. "If it had hopped off the log, it could have got away easily." But because terns nest in trees, the chick likely viewed the ground as a dangerous place, and so it stayed put on the log in spite of the approaching reptile, he said.

The tern's decision proved fatal. After about 90 seconds of pursuit along the log, the tortoise clamped its beak around the bird's head, killing it instantly. "From first approach to the death of the chick, the interaction took seven minutes in total," the authors wrote in their report.

After recording this grisly interaction, Zora emailed Gerlach, who has studied giant tortoises since 1996. When Zora wrote that she’d seen a tortoise hunting a bird, Gerlach was doubtful. "I thought, 'Yeah, that doesn't sound likely. There's some sort of misunderstanding here,'" Gerlach told Live Science. But upon seeing the footage for himself, he was amazed.

"It's clearly trying to injure the bird. And then it goes, it goes all the way and kills it," he said. He and Zora suspect that the tortoise had experience hunting down terns on logs, given that it spotted and approached the chick from some distance away, apparently knowing that it wouldn't fly off as an adult tern would.

Although they primarily stick to a plant-based diet, tortoises occasionally snack on the flesh of dead animals, which are likely a useful source of protein, the authors wrote in their report. Although tortoises' serrated beaks aren't adapted for biting or chewing flesh, if they manage to swallow an animal whole they can still digest the meat, Gerlach said. Tortoises have also been observed munching on bones and snail shells, which provide the animals with calcium, the authors wrote.

In terms of hunting behavior, there are some published reports of tortoises squashing small birds or crabs beneath the edge of their upper shells, but it's unclear whether the tortoises use this as a deliberate hunting strategy or if they're just clumsy, the authors wrote. Anecdotally, there have been several accounts of tortoises seemingly hunting small birds, but until now none had been caught on camera, Gerlach said. The newly documented evidence of a tortoise hunting a bird hints that the animals might hunt other small creatures, perhaps using a variety of strategies, he said.

Gerlach plans to investigate the behavior further to determine how many Seychelles tortoises hunt birds, and how often. He said he wonders whether this behavior may become more common on Frégate as birds recolonize the island, as the island has undergone extensive habitat restoration in recent years. "We may be looking at the redevelopment of behaviors that used to exist in the past," when thriving bird and tortoise populations both inhabited the island, "or we may be looking at the evolution of a totally new behavior," brought on by the recent surge of seabirds, he said.

Whatever the case, the behavior is "so alien to the way we think of tortoises" and suggests that their behavior may be more complex than once thought, Gerlach said.

Originally published on Live Science. 

About 90 million years ago, a giant turtle in what is now central China laid a clutch of tennis ball-size eggs with extremely thick eggshells. One egg never hatched, and it remained undisturbed for tens of millions of years, preserving the delicate bones of the embryonic turtle within it.

In 2018, a farmer discovered the egg and donated it to a university. Now, a new analysis of this egg and its rare embryo marks the first time that scientists have been able to identify the species of a dinosaur-age embryonic turtle.

This specimen also sheds light on why its species, the terrestrial turtle Yuchelys nanyangensis, went extinct 66 million years ago at the end of the Cretaceous period, when the dinosaur-killing asteroid struck Earth. The thick eggshell allowed water to penetrate through, so clutches of eggs were likely buried in nests deep underground in moist soil to keep them from drying out in the arid environment of central China during the late Cretaceous, the researchers said.

While these turtles' unique terrestrial lifestyle, thick eggs and underground nesting strategy may have served them well during the Cretaceous, it's possible that these specialized turtles couldn't adapt to the cooler "climatic and environmental changes following the end-Cretaceous mass extinction," study co-researcher Darla Zelenitsky, an associate professor of paleobiology at the University of Calgary in Canada, told Live Science.

Related: Photos: These animals used to be giant 

Egg-cellent discovery

The farmer discovered the egg in Henan province, a region famous for the thousands of dinosaur eggs people have found there over the past 30 years, Zelenitsky said. But in comparison with dinosaur eggs, turtle eggs — especially those with preserved embryos — rarely fossilize because they're so small and fragile, she said.

The Y. nanyangensis egg, however, persisted because it's a tank of an egg.

At 2.1 by 2.3 inches (5.4 by 5.9 centimeters) in size, the nearly spherical egg is just a bit smaller than a tennis ball. That's larger than the eggs of most living turtles, and just a tad smaller than the eggs of Galápagos tortoises, Zelenitsky said. 

The eggshell's 0.07 inch (1.8 millimeters) thickness is also remarkable. To put that in perspective, that's four times thicker than a Galápagos tortoise eggshell, and six times thicker than a chicken eggshell, which has an average thickness of 0.01 inch (0.3 mm). Larger eggs tend to be thicker, like the 0.08-inch-thick (2 mm) ostrich eggshell, but "this egg is much smaller than an ostrich egg," which average about 6 inches (15 cm) in length, Zelenitsky said.

An equation that uses egg size to predict the length of the carapace, or the top part of the turtle's shell, revealed that this thick egg was likely laid by a turtle with a 5.3-foot-long (1.6 meters) carapace, the researchers found. That measurement doesn't include the length of the neck or head, so the mother turtle was easily as long as some humans are tall.

Doomed egg

The researchers used a micro-CT scan to create virtual 3D images of the egg and its embryo. By comparing these images with a distantly related living turtle species, it appears that the embryo was nearly 85% developed, the researchers found. 

Part of the eggshell is broken, Zelenitsky noted, so "maybe it tried to hatch," but failed. Apparently, it wasn't the only embryonic turtle that didn't make it; two previously discovered thick-shelled egg clutches from Henan province that date to the Cretaceous — one with 30 eggs and another with 15 eggs — likely also belong to this turtle's now-extinct family, known as Nanhsiungchelyid, the researchers said.

Turtles in this family — relatives of today's river turtles — were very flat and evolved to live entirely on land, which was unique during that time, Zelenitsky said. 

The study of the newfound egg is special for its virtual 3D analysis of the embryo, which helped lead to its species diagnosis, said Walter Joyce, a professor of paleontology at the University of Fribourg in Switzerland, who was not involved in the study. Furthermore, this study offers evidence that Nanhsiungchelyid turtles were "adapted to living in harsh, terrestrial environments, but laid their large, thick-shelled eggs in covered nests in moist soil," Joyce told Live Science in an email.

The study will be published online Wednesday (Aug. 18) in the journal Proceedings of the Royal Society B: Biological Sciences.

Originally published on Live Science.

On the island of St. Helena in the South Atlantic, there lives a creature that Guinness World Records has dubbed the "world's oldest animal on land." His name is Jonathan, and he's a giant tortoise. According to Guinness World Records, Jonathan was 187 years old in 2019. Born in 1832, during the reign of Queen Victoria, he was already 80 years old when the Titanic sank deep into the North Atlantic. 

Jonathan and other giant tortoises aren't the only turtles that live a long time, said Jordan Donini, a professor of biology and a turtle ecologist at Florida SouthWestern State College. Sea turtles can live 50 to 100 years, and box turtles can live more than a century, he told Live Science. In fact, scientists don't know the upper limit on many turtle species' life spans, simply because individual humans don't live long enough themselves to find out.

So why do turtles live so long? There's an evolutionary answer and a biological answer, said Lori Neuman-Lee, an assistant professor of physiology at Arkansas State University who studies turtles and other reptiles.

Related: How long do tardigrades live?

The evolutionary answer is relatively straightforward: Animals such as snakes and raccoons love to eat turtle eggs. To pass on their genes, turtles have to live a long time and breed frequently, sometimes multiple times per year — and lay a lot of eggs. "It is kind of amazing that the world is not overrun by turtles, given how many offspring they have," Neuman-Lee told Live Science.

The biological mechanism behind turtles' longevity is more complicated.

One clue to turtles' longevity lies in their telomeres, structures composed of noncoding strands of DNA that cap the ends of chromosomes, Neuman-Lee said. These structures help protect the chromosomes as cells divide. Over time, telomeres get shorter or degrade, which means they can no longer protect their chromosomes as well, leading to issues with DNA replication. And errors in DNA replication can lead to issues such as tumors and cell death.

But turtles exhibit a lower rate of telomere shortening compared with shorter-lived animals, Neuman-Lee said. This means they're more resistant to certain kinds of damage that can arise from DNA-replication errors.

Scientists haven't confirmed all of the factors that contribute to turtles' long lives, but they have proposed some ideas. In a paper posted July 8 to the preprint database bioRxiv that has not yet been peer-reviewed, a team of scientists explored a number of mechanisms and substances that lead to cell damage and death, and looked at how cells from several turtle species, including from a giant tortoise (like Jonathan), responded.

According to the paper, giant tortoises and a few other turtle species seem to be able to protect themselves from the long-term effects of cell damage. They do this by quickly killing off damaged cells, using a process called apoptosis, or programmed cell death, Neuman-Lee said. 

One treatment induced oxidative stress, a type of stress that occurs naturally in living cells. Oxidative stress is caused by free radicals, which are highly reactive molecules formed naturally by metabolic processes. When treated, the turtle cells quickly underwent apoptosis. 

"One of the things that this paper reinforces is this idea that actually controlled apoptosis is really valuable, because if there is a cell that has damage, then if an organism can remove it quickly, then that can avoid things like cancer," Neuman-Lee said.

In fact, the cells in all but one of the species did not respond to a treatment that was supposed to disrupt an enzyme called ligase, which is essential to the process of DNA replication. In other words, the turtles' ligase continued to function properly. Whether this means these turtles are completely resistant to DNA-replication issues is yet to be determined, Neuman-Lee said. But it's one possible answer for why turtles are so long-lived.

Originally published on Live Science.

About 236,000 people drown every year, according to the World Health Organization. Humans aren't the only animals that drown, of course; dogs, snakes, birds and more can drown when they're caught in water with no way to escape. But what about fish and other marine animals? Can animals that live in the water also suffocate in it?

"Marine animals also need oxygen to live," said Frances Withrow, a marine scientist at Oceana, an environmental protection and conservation organization. "It's just that they live off of dissolved oxygen, while we get oxygen from the air." 

Most fish breathe when water moves across their gills. But if the gills are damaged or water cannot move across them, the fish can suffocate. They don't technically drown, because they don't inhale the water, but they do die from a lack of oxygen.

Fishing equipment, such as some types of hooks, can damage the gills. Disease can also be the cause. Pathogens, mainly bacteria, may attach to the gills, blocking them so they can't filter oxygen from the water or degrading them to the point where they no longer work. "It's just like if we had a really bad respiratory disease," Withrow said. "It makes it [the animal] work harder to breathe."

Related: What's the biggest freshwater fish in the world?

Although some fish can pump water across their gills while at rest, many fish must swim constantly so that water flows past them. If they get trapped, such as in a fishing net, they may get stuck and suffocate, Withrow told Live Science.

Sharks need their fins to swim. Some fishers catch sharks and remove their fins for foods such as shark fin soup and then toss the shark back into the water because the rest of the animal may not be valuable on the market. "This is often an illegal activity because it's unsustainable," Withrow said. "Not only is it not great for the general populations of sharks, but it's pretty cruel." The shark can't swim when it's tossed back in, so it will be eaten by predators, die of starvation or suffocate.

Other marine animals, such as turtles and dolphins, get air the way we do — they breathe it from the air. But they can only do it when they surface. Fishing equipment can trap them underwater, preventing them from doing so.

Drift gill nets, or giant nets that float in the water and are not designed to target a particular species of fish, are a major culprit. "Depending on the size of the net, it will catch anything that swims by," Withrow said. This includes fish, sea turtles and marine mammals that the fishers don't intend to sell. Other types of fishing equipment have ropes that can entangle animals, like whales, and prevent them from surfacing.

It's difficult to know how many marine animals suffocate, Withrow said, but entanglement kills 300,000 whales, dolphins and porpoises each year, the International Whaling Commission estimates.

Sometimes, areas of the ocean may not have enough dissolved oxygen to support the fish that live there. One way this can happen is if many plankton bloom simultaneously after sufficient nutrients become available. The plankton use up all the oxygen in a short period, causing fish in the area to suffocate. "The ocean is always mixing, but in strange ways," Withrow said. "So the water isn't always able to replenish that oxygen very quickly."

Moreover, warm water doesn't hold as much dissolved oxygen as cold water does, according to the U.S. Geological Survey. As ocean temperatures increase due to climate change, "dead zones" with lower oxygen levels are emerging, Live Science previously reported.

Originally published on Live Science.

A giant tortoise in the Galápagos Islands that was thought to have gone extinct over a century ago just came out of hiding.

Researchers discovered the female tortoise on the Galápagos' Fernandina Island during a joint expedition carried out by the Galápagos National Park Directorate and the Galápagos Conservancy in 2019, according to a statement. They nicknamed her "Fernanda."

At the time, the team "was confident" that the lone tortoise was the "lost" Fernandina Giant Tortoise (Chelonoidis phantasticus), a species native to the island that was thought extinct for 112 years due to eruptions of the Fernandina Volcano, according to the statement. But to confirm, they sent blood samples to geneticists at Yale University.

Related: In images: Wacky animals that lived on Mauritius

The team at Yale compared this tortoise's genes to those of the only other tortoise that scientists have found on Fernandina Island, a male Chelonoidis phantasticus discovered in 1906. The Yale team confirmed that the two were closely related and that Fernanda was indeed the same species.

"One of the greatest mysteries in [the] Galápagos has been the Fernandina Island Giant Tortoise. Rediscovering this lost species may have occurred just in the nick of time to save it," Dr. James Gibbs, vice president of Science and Conservation at the Galápagos Conservancy and tortoise expert at the State University of New York, said in the statement. "We now urgently need to complete the search of the island to find other tortoises."

The researchers are hoping to avoid what happened to the famous Lonesome George, a tortoise that was the last of another species called the Pinta Island tortoise (Chelonoidis abingdoni). He died in June 2012, at around 100 years old, bringing the end of his species despite breeding efforts, Live Science previously reported.

"We desperately want to avoid the fate of Lonesome George," Danny Rueda Córdova, the director of the Galápagos National Park Directorate, said in the statement. "My team from the Park and Galápagos Conservancy are planning a series of major expeditions to return to Fernandina Island to search for additional tortoises beginning this September."

Scientists discovered traces of at least two other tortoises that may be from Fernanda's species on the Fernandina Volcano during the expedition. 

If they find a male giant tortoise of the same species, the team will attempt to unite him with Fernanda at the Galápagos National Park's Giant Tortoise Breeding Center in Santa Cruz and encourage their breeding; if successful, conservationists would raise the young in captivity and then bring them back to Fernandina.

The number of giant tortoises on the Galápagos Islands significantly declined in the 19th century due to exploitation by whalers and buccaneers, according to a statement. 

Now, the population of giant tortoises in the Galápagos is thought to only be between 200,000 to 300,000 individuals, about 10% to 15% of what they were historically. 

Originally published on Live Science.

Paleontologists in Madagascar recently discovered an exceptionally well-preserved fossil of a new and extinct species of turtle, dating back to the late Cretaceous Period, which began around 100 million years ago. The newly discovered species would have had a frog-like face and eaten by sucking in mouthfuls of prey-filled water.

The ancient turtle was a freshwater species endemic to Madagascar, with a shell length of around 10 inches (25 centimeters). It had a flattened skull, rounded mouth and large tongue bones, all of which would have made it a great suction feeder and given it an amphibian-like appearance. In a new study describing the species, the researchers named it Sahonachelys mailakavava, which means "quick-mouthed frog turtle" in Malagasy, the language spoken by Indiginous people of Madagascar.

Researchers unearthed the turtle's fossil in 2015 while searching for the remains of dinosaurs and crocodiles at a site on the island with a history of such finds. While removing the overburden — the typically bare layers of sediment above fossil-rich layers — the team was surprised to find bone fragments from a turtle's shell and eventually recovered an almost intact skeleton.

Related: Sea science: 7 bizarre facts about the ocean 

"The specimen is absolutely beautiful and certainly one of the best-preserved late Cretaceous turtles known from all southern continents," lead author Walter Joyce, a paleontologist at the University of Fribourg in Switzerland, told Live Science. "In all regards, this is an exceptionally rare find."

The researchers are unsure how far back the quick-mouthed frog turtle may have emerged or when and why it went extinct; but the new species "likely survived the big extinction event that killed the dinosaurs" and brought the Cretaceous Period to an end around 66 million years ago, Joyce said.

Suction feeders 

Quick-mouthed frog turtles were most likely suction feeders, the researchers said.

"This is a specialized mode of underwater feeding, during which the animal quickly opens its mouth and expands its throat to quasi-inhale a large volume of water, including the desired prey item," which would have included plankton, tadpoles and fish larvae, Joyce said.

Its flattened skull, mouth shape and delicate jaws are all telltale signs that this turtle used suction for feeding. "Suction feeders need to quickly create a large circular opening through which they suck water," Joyce said. "As the prey items are transported directly into the esophagus, suction feeders do not have strong jaws, as they do not bite."

The turtle also had enlarged tongue bones for its size, which suggests it had strong muscles to allow the quick expansion of its throat, Joyce said. 

Convergent evolution 

The quick-mouthed frog turtles belonged to the Pelomedusoidea family, which includes living species such as South American and Madagascan river turtles. "Although the group is not particularly diverse today, its fossil record shows that the group nearly conquered all landmasses in the past and was much more diverse," Joyce said.

The quick-mouthed frog turtle was "likely the first Pelomedusoid" to have evolved as a suction feeder "to such an extreme," Joyce said. There are several modern-day turtle species that suction feed, most of which belong to the family Chelidae and evolved separately from the quick-mouthed frog turtle. 

When Joyce first saw the skull, he thought it belonged to a Chelid, he said. "The shell, however, clearly showed that it is a Pelomedusoid." This is evidence of convergent evolution and means Chelids and Pelomedusoids, which are distantly related, have each evolved this ability independently of one another, Joyce said.  

"It highlights that distantly related animals will converge upon the same shape when adapting to similar lifestyles," Joyce said.

The study was published online May 5 in the journal Royal Society Open Science.

Originally published on Live Science.

Editor's note: This story was updated on May 6 to include comments from Dan Crear. The original story was published on May 4.

Green sea turtles venture into the open ocean immediately after hatching on the Florida coast, and then seem to vanish for a spell — now, new tracking data shows that, after surfing the Gulf Stream northward, many turtles drop out of the current to enter the Sargasso Sea, an oasis of cozy seaweed and plentiful food.

In the new study, published Tuesday (May 4) in the journal Proceedings of the Royal Society B, scientists attached solar-powered satellite tags to 21 green sea turtles (Chelonia mydas) of "toddler" age, meaning about 3 to 9 months old. The young turtles weighed just over 10.5 ounces (300 grams) and their shells measured about 5 to 7 inches (12 to 18.6 centimeters) long; tagging such small creatures presented a huge challenge, both due to their initial size and the fact that they grow and change shape fairly rapidly, compared with mature animals.

Despite the hurdles, to better protect sea turtle populations, "we really need to get tags on some of these little guys," said first author Kate Mansfield, director of the Marine Turtle Research Group and an associate professor in the biology department at the University of Central Florida. Young turtles' migration into the open ocean is often referred to as "the lost years," since scientists know so little about what the animals get up to before they return to the coast as "teenagers."

Related: Top 10 most incredible animal journeys

"Sea turtles, in general, don't reach maturity for at least a couple decades. And those years leading up to when they become adults, we don't know much about them," Mansfield said. Now, thanks to the tracking data, "the Sargasso Sea is emerging as an important habitat for sea turtles in their early life stages," marking the region as critical for conserving the species, she said. 

The adventures of turtle toddlers 

The Sargasso Sea, named for a free-floating genus of brown algae called Sargassum, is the only sea whose edge is defined by ocean currents, rather than land boundaries, according to the National Oceanic and Atmospheric Administration (NOAA). The sea sits within the so-called Northern Atlantic Subtropical Gyre, a big circle made up of four major ocean currents: the Gulf Stream to the west, the North Atlantic Current to the north, the Canary Current to the east and the North Atlantic Equatorial Current to the south. 

In past studies, researchers caught sight of young green sea turtles, as well as loggerheads (Caretta caretta), passively drifting in these currents, often on a mat of Sargassum, Mansfield said. These observations, as well as sightings of the Florida-borne turtles in the east Atlantic, hinted that turtles may just make a big loop around the gyre before heading back to the U.S. as juveniles.

But Mansfield and her colleagues wanted to get hard evidence of this migration, while also pinning down how long the turtles typically stay offshore. Are they away for one year, "or are they out for a decade? These are pretty fundamental questions," said study author Jeanette Wyneken, a professor of biological sciences at Florida Atlantic University. 

Satellite tags designed for adult turtles "looked like a brick" about the size of a cell phone, Mansfield said; but with the advent of small tags, about the length of a finger segment, the team could start tracking young turtles, she said. They began with loggerheads and tagged 17 turtles in a 2014 study; they found that, rather than passively drifting along, the loggerheads frequently exited the currents to swim toward warm, nutrient-dense waters, including those in the Sargasso Sea, they reported in the journal Proceedings of the Royal Society B. 

Green sea turtles may be similarly active swimmers once they reach the open sea, the team thought, so they set out to repeat the study with C. mydas hatchlings.

The team collected the hatchlings from Boca Raton, located on the southeast coast of Florida, and then brought them back to the lab to rear for several months. Though the teams' satellite tags are small, they're still too large for freshly hatched turtles, Mansfield noted. 

"I think a limitation to the study is that researchers have to wait until turtles reach a certain size before they can tag them," said Dan Crear, a marine spatial ecologist currently working with NOAA's Highly Migratory Species Management Division, who was not involved in the study. "This interrupts the natural transition from hatching to these ocean areas," so the results may be somewhat biased by where and when the team released the turtles, Crear told Live Science in an email. This limitation could potentially be overcome in the future, assuming smaller tags become available, he added. 

The team initially attempted to attach the tags using the same adhesive they had used for the loggerheads, a kind of manicure acrylic that eventually peeled off as the animals grew. 

"But that didn't work with the green turtles," Mansfield said. The texture of a young green turtle's shell feels "waxy," somewhat like a human fingernail doused in cuticle oil, whereas loggerhead shells aren't so slick, Wyneken said. The team tried many adhesives — those used to cement fillings in teeth, those used to attach theatrical prosthetics to skin, you name it — before finding one that would stick to the slippery turtles. 

That ended up being a marine urethane adhesives, normally used to seal boats; the glue is flexible enough to stretch as the turtles grow, but once the turtles reach a certain size, it pops right off.

After ensuring the adhesive was safe and sticky enough, the team released their turtles into the western Atlantic and tracked them for an average of 66 days; they were able to follow several turtles for more than 100 days, and one for 152 days. They found that their turtles mostly swam near the surface of the ocean, similar to the loggerheads, and also coasted along the Gulf Stream. However, in general, the turtles dropped out of the Gulf Stream and adjacent North Atlantic Current sooner than the loggerheads did.

About two-thirds of these green sea turtles then high-tailed it toward the Sargasso Sea, where they stayed until their tags ceased to transmit; this hinted that the Sargasso serves as an appealing nursery for the turtles. 

"That habitat, it makes sense," Mansfield said. The seaweed provides camouflage for the teeny turtles, while also slowing the flow of water and thus allowing the sun to heat its surface. Being cold-blooded, sea turtles require warm water to survive and their growth slows significantly when they get too chilly. Other juvenile marine animals, such as shrimp, crab and fish, also grow up in the Sargassum and provide food for the growing turtles.

But while a proportion of young sea turtles flock to the Sargasso, there's still the question of why some swim toward the sea while others remain in the current, Mansfield said. It may be linked to the fact that the quantity of Sargassum and its distribution along the eastern U.S. varies by season, according to a 2011 study in the International Journal of Remote Sensing.  

So while some turtles encounter the Sargassum in the Gulf Stream and follow it into the Sargasso Sea, "there may be some that miss that Sargassum boat and hang out in the currents," Mansfield said.

In future studies, "looking at how these relationships [to Sargassum] change seasonally and annually will help paint a clearer picture of where and why these younger turtles are where they are," Crear said. 

And when the turtles do reach the Sargasso Sea, another question emerges: How long do they stay?

"I would guess those animals would be out there for maybe two to three years," Wyneken said, but that's a "pure guess," she added. "If you're in a safe place, why leave it?" Mansfield said, echoing Wyneken's sentiment. Green sea turtles typically return to Florida as juveniles and remain in the coastal habitat until adulthood, feasting on algae, seagrasses and jellyfish. Until they reach that critical transition point, the Sargasso Sea likely fills many of the turtle toddlers' needs. 

But to know exactly how long they remain in the seaweed-laden habitat, scientists will need more tracking data, Mansfield said. Now that they've tracked turtles on their way to the Sargasso, the team could potentially search for turtles already living there and attach tags to them on-site, she said. Regardless of how long the turtles stay, the Sargasso appears to be an important habitat for the young animals. To ensure the turtles grow up to lay their own eggs in the future, the sea must be conserved, she said. 

"The Sargasso Sea can't become another garbage dump. It has to be recognized as a habitat that's important to imperiled species," Wyneken said. "It's probably not just a green turtle story," given that other juvenile marine animals also grow up among the seaweed, she added.

Originally published on Live Science.

North Pacific loggerhead sea turtles (Caretta caretta) hatch on the shores of Japan and spend much of their time in the open Pacific, but sometimes mysteriously crop up in Mexico, 9,000 miles (14,500 kilometers) away from their original nesting ground.

That incredible journey requires them to pass through potentially deadly, cold waters that should be inhospitable to them, since loggerheads rely on warmth from the surrounding environment to maintain their core body temperatures. Now, scientists have a clue as to how the turtles survive this epic migration.

"This mystery had been around for decades, and nobody had a clue how to explain it," said senior author Larry Crowder, a professor of marine ecology and conservation at Stanford University's Hopkins Marine Station and a senior fellow at the Stanford Woods Institute for the Environment.

Along the North American Pacific coast, seasonal winds from the north periodically sweep down the shoreline, pushing warm surface waters offshore. Cold water from the deep ocean then rises up to replace that warm water, dragging up an abundance of nutrients with it. Tropical animals, including loggerheads, rarely venture into these cold waters from the open Pacific, Crowder said. Charles Darwin even described the region as "impassable" for warm-water-loving critters, he added. 

Related: Top 10 most incredible animal journeys 

But according to the new study, published April 8 in the journal Frontiers in Marine Science, loggerheads may have a fleeting opportunity to reach the Mexican coast during El Niño, a climate cycle that shifts warm water in the western tropical Pacific Ocean eastward along the equator.

"A warm 'door' needs to open for these turtles to get to Mexico," Crowder told Live Science. The study authors refer to this temporary door as a "thermal corridor" — essentially a passageway of warm water. "During El Niño, the turtles get a shot at going across." 

This study not only sheds light on a long-standing mystery but could also provide critical information for protecting loggerheads, which are considered "vulnerable" by the International Union for Conservation of Nature (IUCN). Conservation efforts may need to adapt as the turtles react to warming waters, driven by climate change, Crowder said. 

"With climate change comes increasingly warmer sea surface temperatures and longer periods of warm water events in the Pacific Ocean," said Carolyn Kurle, an associate professor of biological science at the University of California, San Diego, who was not involved in the study.

If the thermal corridor hypothesis is true, more loggerhead juveniles may migrate to the North American coast over time, Kurle told Live Science in an email. This could be beneficial to young turtles, since the ample nutrients in these coastal waters boost the turtles' food supply, she said. "But it would be terrible" if more young turtles accidentally became ensnared in fishing nets along the coast, especially since those turtles would not have the chance to return to Japan and mate, Kurle told Live Science. 

A decades-long mystery 

Loggerheads can be found all over the world, primarily in subtropical and temperate waters, and are divided into nine subpopulations, including the North Pacific subpopulation, according to the National Oceanic and Atmospheric Administration (NOAA). Scientists first got a clue that North Pacific loggerheads migrate between Mexico and Japan when Adelita, a female turtle, was released from captivity in Baja California in 1996 and immediately made a beeline for East Asia, Crowder said. 

Marine biologist Wallace Nichols had attached a satellite-tag to Adelita, so he was able to track her entire journey to Japan, according to PBS. Crowder and his co-authors used similar tracking data for their new study, but they pulled from an enormous dataset of 231 juvenile loggerheads whose migratory patterns had been monitored for 15 years.

About 97% of these loggerheads remained in the open ocean and did not venture toward the North American coast. In fact, when these turtles did near the edge of the coastal ecosystem, they promptly turned around. Dana Briscoe, a postdoctoral researcher in Crowder's lab at the time, found that the timing of the turnaround appeared to be driven by Earth's magnetic field, which the turtles can sense and use to navigate through the ocean. Presumably this ability helps them avoid cold water, Crowder said.

However, Briscoe noticed that not all the turtles turned around at the typical point — six of the 231 turtles just continued on their merry way and swam right into coastal waters, entering an area known as the California Current Large Marine Ecosystem (CCLME). The team looked closer at these six outliers and found that they each made their journey in the spring, and based on data gathered from remote sensors, these wandering turtles "experienced unusually warm conditions," compared with their counterparts.

"And the two that made it closest to Baja experienced the warmest water conditions," Crowder said. Seeing this connection to warm water, the team developed their thermal corridor hypothesis.

Related: The reality of climate change: 10 myths busted

But because only six turtles out of 231 — roughly 3% — entered the CCLME, the team needed more data to back up their idea. So they teamed up with Calandra Turner Tomaszewicz, a scientist at the NOAA Southwest Fisheries Science Center, whose group had been studying the bones of turtles that had stranded in Mexico and died on the shore. 

Sea turtle bones contain annual growth rings, similar to trees. A new ring grows around the outside of the bone each year, while one ring erodes from the center of the bone. A turtle's humerus bone, a type of leg bone, has about six to eight growth rings at any given time, Crowder said. 

These growth rings contain clues about what a turtle ate in a given year, in the form of stable isotopes, which are chemical elements with different numbers of neutrons. Provided a scientist knows when the turtle died, they can use these chemical clues to determine what the turtle ate throughout its life, and therefore, where that turtle was likely located. 

"And the stable isotope ratios in open ocean-food, like jellyfishes, is dramatically different than in crabs," which is what a loggerhead would eat in coastal waters, Crowder said. In this way, the team determined when a given turtle made the jump from open to coastal waters. They then looked up water temperatures in that year.

Turner Tomaszewicz and her colleagues analyzed the growth rings of 33 loggerheads in Mexico and found that more than 60% of the turtles entered the region near the shore in a year with warm ocean conditions. Grouping the turtles by year revealed that far more turtles arrived in Mexico in the warm years than cool ones.

"The bone growth layer analyses absolutely strengthened their thermal corridor hypothesis," supporting the idea that these transient passages of warm water help more turtles reach the North American coast, Kurle said. 

The hypothesis might also explain why loggerhead turtles from Japan cropped up in San Diego Bay in 2016, an El Niño year, Crowder said. The turtles only rarely show up in southern California, and even then, they don't usually appear in large groups, as they did that year, according to The San Diego Union-Tribune. The strange event led some scientists to wonder whether, with climate change, loggerheads might come to San Diego more often.

Of course, the thermal corridor hypothesis is still just that — a hypothesis. Ideally, the team would be able to satellite-tag more loggerheads, track their movements and see how many migrate to Mexico in El Niño years, compared with cool La Niña years , Kurle said. However, seeing that so few turtles seem to enter the CCLME, this effort would likely be expensive and impractical, Crowder said. Instead, he said he hopes to conduct an experimental study with a few dozen turtles, where two groups of loggerheads would be released into the open ocean near the CCLME boundary, one in a El Niño year, and one in a La Niña year.

But for now, even with its limited data, the current study "will help those who seek to understand and manage this vulnerable species with one of the longest migrations in the animal kingdom," Kurle told Live Science.

Originally published on Live Science. 

While some people slather mayonnaise on their sandwiches, Israel's National Sea Turtle Rescue Center uses the condiment for a unique purpose: to treat endangered turtles after oil spills, The Associated Press (AP) reported.

More than 100 miles (160 kilometers) of Israel's Meditteranean coastline became blotted with huge globs of tar last week, after an oil spill occurred about 31 miles (50 km) offshore, Live Science previously reported. Israel's Nature and Parks Authority (INPA) called the spill "one of the most serious ecological disasters" the country has ever seen, and the hundreds of tons of oil pose a particularly serious threat to sea turtles, since they breathe and feed at the water's surface. 

Many tar-coated turtles have already washed ashore, some dead, but the National Sea Turtle Rescue Center was able to transport 11 endangered green sea turtles (Chelonia mydas) to Michmoret, north of Tel Aviv, for medical treatment, the AP reported. 

Related: Science you can eat: 10 things you didn't know about food 

"They came to us full of tar. All their trachea from inside and outside was full of tar," Guy Ivgy, a medical assistant at the center, told the AP. To clear the tar from the turtles' digestive tracts, the medical team turned to mayonnaise and similar fatty substances, "which practically clean the system and break down the tar," allowing the turtles to poop it out, Ivgy said. 

So how exactly does this critical component of a B.L.T. sandwich help the turtles? 

Well, mayonnaise is an emulsion, meaning a uniform mixture of two liquids that don't normally mix well, in this case, oil and water, according to The Guardian. The water comes from egg yolks, which are about 50% water, and some form of liquid acid, usually lemon juice or vinegar. To make mayo, one must vigorously whisk the yolks and acid together and then slowly dribble in the oil; this process disperses tiny droplets of the oil between droplets of water, eventually creating a uniform sauce. 

The oil droplets remain suspended in the water thanks to a molecule in the yolks called lecithin; the molecule is hydrophilic on one side, meaning it can stick to water, and hydrophobic on the other, meaning it repels water, according to Smithsonian Magazine. The lecithin molecules surround each droplet of oil, hydrophilic ends pointing out, so the water and oil don't repel each other and cause the mayonnaise to split.

Because mayonnaise has both hydrophobic and hydrophilic properties, it can interact with both the oily, hydrophobic tar and hydrophilic molecules in a turtle's digestive tract. The hydrophobic oil can mix with the tar, making it thinner and less viscous; meanwhile, the hydrophobic ends of the lecithin molecules are also drawn towards the tar, with their hydrophilic ends facing out. This creates a barrier around the tar that better interacts with water, making the toxic substance less sticky.

That's why spoonfuls of mayonnaise can help flush out the guts of tar-laden turtles in Israel, and it's also why mayonnaise can treat hot tar burns, allowing emergency room doctors to easily wipe away tar without causing further skin damage, according to a 2014 report in the Journal of the Pakistan Medical Association.

Thanks to the mayo, the rescued turtles are expected to recover in one to two weeks, after which they'll be released into the wild.

Read more about the turtles at The Associated Press. 

Originally published on Live Science. 

This week, thousands of sea turtles were paralyzed in the frigid waters along the Texas coastline during the unprecedented winter storm that swept across the country. In response, a small army of volunteers, many of them without power and running water, sprang into action to rescue these endangered creatures. 

So what caused these sea turtles to freeze up?

As temperatures plunged across much of the U. S., the typically warm waters of the Gulf of Mexico fell, too. For sea turtles, such drops can be very risky. As water temperatures fall below 50 degrees Fahrenheit (10 degrees Celsius), the turtles' heartbeats slow down, effectively paralyzing them. Cold-stunned turtles lose their ability to swim and float to the surface. Such cold-stunned sea turtles are at risk from predators, boat strikes and even drowning, according to the National Oceanic and Atmospheric Association.

Related: In photos: Tagging baby sea turtles

This is the largest cold-stunning event to occur in the U.S. since NOAA began keeping records on these events, Donna Shaver, coordinator of the Sea Turtle Stranding and Salvage Network, told National Geographic.

As of Friday (Feb. 19), nearly 7,000 green (Chelonia mydas), loggerhead (Caretta caretta) and Kemp's Ridley sea turtles (Lepidochelys kempii) had been rescued along the Texas coastline. Roughly 5,000 of those rescues occurred along the southernmost tip of that coastline near South Padre Island. All three species are listed as either threatened or endangered by the U.S. Fish and Wildlife Service. 

"The turtles were surprised by the cold just like everyone else," Joseph Pechmann, a herpetologist with Western Carolina University, told Live Science. 

Turtles typically cope with dropping temperatures by moving to warmer water. However, many turtles in this region live there year-round because of the typically mild climate; the temperature simply plunged too quickly for them to react. 

To save these imperiled creatures, an impromptu navy composed of both private boats and Texas game warden vessels, primarily organized by the nonprofit organization Sea Turtle, Inc, spent the week scooping the chilly, immobilized reptiles from the water, while other volunteers combed the beaches for turtles that had washed ashore.

This is all during a winter storm that left many humans without heat, power and running water. 

But the real challenge wasn't rescuing the turtles; it was keeping such a huge number of them warm on land. Right now, just under 5,000 sea turtles are "dry-docked" on the floor of both Sea Turtle, Inc.'s rehabilitation facility and the South Padre Island Convention Center, according to Texas Monthly. There, the paralyzed turtles are being kept warm on tarps inside facilities powered by donated generators. Photos show thousands of turtles arrayed over a space the size of a football field, looking like pebbles on a dry creek bed. Wendy Knight, the director of Sea Turtle, Inc., told NPR that the turtles cannot be released until water temperatures reach at least 55 F (13 C). 

"It's a huge, huge community effort," Gina McLellan, a volunteer who has spent the week transporting turtles to shelter in her own car, told the Washington Post. "With this kind of event, it's a classic display of humanity toward animals."

Originally published on Live Science.

 The world's most endangered turtle species may now have a fighting chance, after a 3-foot-long (1 meter) female — a potential mate for the lone known male of the species — was discovered in Vietnam. 

Researchers from the Asian Turtle Program (ATP) of Indo-Myanmar Conservation (IMC) and the Wildlife Conservation Society (WCS) discovered the 182-pound (86 kilograms) turtle in Dong Mo Lake, in Hanoi's Son Tay district, in October last year. They analyzed genes in her blood and have now confirmed she is a Swinhoe's softshell turtle (Rafetus swinhoei), making her the second known living member of the species.

They hope that the female will be able to mate with the last known captive male, currently living at Suzhou Zoo in China, and provide a lifeline for this dying species. 

Related: This may be the biggest turtle that ever lived

The Swinhoe's softshell turtles, also known as Yangtze giant softshell turtle and Hoan Kiem turtle, were once abundant in the region; their numbers have dwindled though, as locals killed them for meat and poachers stole their eggs, which were sold in China as traditional medicine, according to The Guardian.

"In a year full of bad news and sadness across the globe, the discovery of this female can offer all some hope that this species will be given another chance to survive," Hoang Bich Thuy, the director for the WCS in Vietnam, said in a statement.

The last other known female Swinhoe's softshell turtle died in April 2019 at Suzhou Zoo in China, where she was paired with the male that still resides there today. Unfortunately, the two were unable to naturally reproduce, and she died unexpectedly after being put under anesthesia in an attempt at artificial insemination, according to The Guardian.

The hope is that the new female, which continues to be monitored at Dong Mo Lake, will successfully reproduce with the male or at least be able to survive the artificial insemination procedure that killed her predecessor.  

Observers have also spotted another potential Swinhoe's softshell turtle in Dong Mo Lake, which the researchers believe could be another male due to its larger size. The team has also detected environmental DNA (eDNA) traces, primarily made up of old skin cells left behind in the water, in the nearby Xuan Khanh lake, suggesting the presence of another individual. They are now aiming to catch both in the spring, as water levels drop, and identify their sexes.

"Once we know the sex of the animals in Vietnam, we can make a clear plan on the next steps, hopefully we have a male a female, in which case breeding and recovery of the species becomes a real possibility," Timothy McCormack, Program Director of the ATP/IMC, said in the statement.

 Originally published on Live Science. 

Baby leatherback sea turtles are doing better than they have in years, now that many humans are opting (or being ordered) to stay off beaches due to the COVID-19 pandemic. 

On one beach in Thailand, for instance, environmentalists have found 11 leatherback sea turtle (Dermochelys coriacea) nests since November, the largest number of nests found there in the past two decades, according to The Guardian. 

Likewise, on Florida's 9.5-mile-long (15 kilometers) Juno Beach, marine life researchers found 76 leatherback sea turtle nests, a significant increase compared with the number of nests at this time last year, The Guardian reported.

Related: In photos: Tagging baby sea turtles

Beach closures and shelter-in-place orders to help people maintain social distancing during the pandemic have inadvertently kept many locals, tourists and even wildlife smugglers away from leatherback sea turtle nests and hatchlings. 

"This is a very good sign for us because many areas for spawning have been destroyed by humans," Kongkiat Kittiwatanawong, the director of the Phuket Marine Biological Centre in Thailand, told The Guardian.

Leatherback sea turtles were so scarce around the Phuket Marine Biological Centre, conservationists hadn't found any nests in the past five years. These turtles also face risks from fishing gear, pollution, climate change and severe weather, according to the International Union for Conservation of Nature (IUCN).

Leatherbacks are the largest living turtle on record. They live all over the world (except for the polar regions) where they dive deep underwater while migrating from nesting areas to feeding hot spots to chow down on jellyfish, the IUCN reported.

In a single reproductive season, mature females can lay between three and 10 clutches of 60 to 90 eggs, the IUCN reported. However, most females wait two years or more between reproductive bouts. And a tiny percentage of these babies — just one in 1,000 — survives.

In late March, park staff in Thailand's southern province of Phang Nga found 84 hatchlings after monitoring the area for two months, The Guardian reported. 

Less human traffic on beaches gives several advantages to these giant turtles, said David Godfrey, the executive director of the Sea Turtle Conservancy in Florida.

"The chances that turtles are going to be inadvertently struck and killed will be lower," Godfrey told West Palm Beach's local CBS 12 news. "All of the reduced human presence on the beach also means that there will be less garbage and other plastics entering the marine environment. Ingestion and entanglement in plastic and marine debris also are leading causes of injury to sea turtles."

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Originally published on Live Science.

An 8-million-year-old turtle shell unearthed in Venezuela measures nearly 8 feet (2.4 meters) long, making it the largest complete turtle shell known to science, a new study reported. 

This shell belonged to an extinct beast called Stupendemys geographicus, which lived in northern South America during the Miocene epoch, which lasted from 12 million to 5 million years ago. 

S. geographicus weighed an estimated 2,500 lbs. (1,145 kilograms), almost 100 times the size of its closest living relative, the Amazon river turtle (Peltocephalus dumerilianus), and twice the size of the largest living turtle, the marine leatherback (Dermochelys coriacea), the researchers wrote in the study.

Related: Photos: These animals used to be giant

Its impressive shell makes this ancient creature "one of the largest, if not the largest turtle that ever existed," study senior researcher Marcelo Sánchez-Villagra, the director of the Paleontological Institute and Museum at the University of Zurich, said in a statement. 

The species likely achieved its colossal size thanks to the warm wetlands and lakes in its habitat, Sánchez noted.

Scientists have known about the colossal S. geographicus since 1976, but the new investigation uncovered even more fossils and secrets about this poorly understood turtle. For instance, large caimans (a type of crocodile) chomped down on S. geographicus shells, and S. geographicus males had horned shells.

Included in the study were shells and the first known lower jaws of these turtles, which came from a 1994 dig in Venezuela's Urumaco region, as well as new finds from the La Tatacoa Desert in Colombia. After examining these fossils, the researchers realized that the male turtles had unique, horn-like weapons at the front of their carapaces, or upper shells.

These horns were likely used as weapons in male-to-male combat, the researchers said. Similar combative behavior is seen today in snapping turtles (Chelydridae), whose males often fight each other to establish dominance in overlapping territories, the researchers said.

An "elongated and deep scar in the left horn" of one of the S. geographicus shells could be a mark from combat between males, the researchers added.

A lone caiman tooth protruded from another shell, suggesting that, though these turtles were large, lurking predators still hunted them, the researchers said.

The study was published online Wednesday (Feb. 12) in the journal Science Advances.

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Originally published on Live Science.

The phrase "what goes in … must come out" took on a literal meaning for a green turtle that had gobbled up human trash, only to poop it out later with help from a veterinarian. 

The green turtle (Chelonia mydas) was initially found tangled in the net of Roberto Ubieta, a fisherman from San Clemente del Tuyú, a town on the Atlantic coast of Argentina. Ubieta, who had received training from the Mundo Marino Foundation on how to help marine reptiles trapped in fishing nets, immediately got to work aiding the turtle.

But when Ubieta brought the animal to the rescue center of the San Clemente institution on Dec. 29, veterinarians there realized that the turtle had other immediate health problems. 

Related: Photos: Butterflies Drink Turtle Tears

A few days after arriving at the center, the turtle began pooping out trash, including fragments of nylon bags and hard plastics. 

X-rays revealed that the turtle had garbage in its belly, likely because the animal had mistaken the trash for its natural food, such as jellyfish, sea grasses and worms, the foundation said.

"Therefore, we began a treatment with a medication that favors its peristaltic movements (movements of the digestive tract) and allows it to eliminate what we observed on the [X-ray] plates," Ignacio Peña, veterinarian at the Mundo Marino Foundation, said in a statement (translated from Spanish with Google translate). 

In all, the turtle defecated 0.5 ounces (13 grams) of garbage, the foundation said. 

Now, the turtle is doing much better. "Today, the turtle is eating green leaves, mainly lettuce and seaweed," Peña said.

This is the third turtle brought to the foundation this year. The same fisherman found a dead green turtle on Jan. 12. A necropsy (an animal autopsy) of that turtle showed that the animal also had plastics in its digestive system. A third turtle survived but also expelled trash, a piece of nylon bag, in its poo.

Animals that mistake trash for food are at risk of death. Garbage can mechanically block their digestive tracts, as well as take up room so there's less space for nutritious meals.

"In addition, a large amount of gas could be generated … [as a] product of the accumulated plastic," Karina Álvarez, biologist and conservation manager at the Mundo Marino Foundation, said in the statement. "Which would affect their ability to dive and immerse, both to feed and to find more suitable temperatures." 

The green turtle, one of the largest sea turtles, is found in tropical and subtropical waters. These animals are endangered, according to the International Union for Conservation of Nature, largely because of humans who overharvest their eggs and hunt the adults, according to the World Wildlife Fund. Green turtles also face habitat loss and are frequently entangled in fishing gear. 

Sea turtles aren't the only aquatic animals to mistake trash for food. Garbage has also ended up inside fur seals living in a remote part of Chile and whales, including a sperm whale that died with a 220-lb. (100 kilograms) "litter ball" in its belly.

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Originally published on Live Science.

A photo of a baby loggerhead sea turtle that died after eating 104 pieces of plastic went viral on Facebook this week. The photo was posted by the Gumbo Limbo Nature Center in Boca Raton, Florida, on Tuesday (Oct. 1) and shows the lifeless turtle, no bigger than the palm of your hand, next to the dozens of small pieces of plastic found in the animal's digestive tract, neatly organized in rows. 

The little turtle found a wide variety of plastic to chow down on. "We found a piece of a balloon. There was a wrapper that goes on the outside of bottles," Whitney Crowder, the sea turtle rehabilitation coordinator at the Gumbo Limbo Nature Center, told the South Florida Sun Sentinel.

Related: Plastic Bag Waste Litters Landscape (Infographic)

This poor hatchling was a "washback" turtle — a baby that swam a few miles out to sea, where it started eating, but washed back to shore after a few weeks. Washbacks this size are around 1 to 2 months old, said Leanne Welch, manager of the Gumbo Limbo Nature Center, which has been rescuing and rehabilitating sea turtles and providing marine science education programs for more than 30 years. 

"It's washback season at Gumbo Limbo and weak, tiny turtles are washing up along the coastline needing our help," Gumbo Limbo Nature Center staff wrote in the Facebook post. "Unfortunately, not every washback survives. 100% of our washbacks that didn't make it had plastic in their intestinal tracts." The plastic clogs up the animal's digestive tract, they wrote. 

"Unfortunately, it's not unique," Welch told Live Science. "I was just down there, and they're necropsying another washback with plastic in it. It's something we see every day." 

Florida beaches serve as nesting grounds for five species of sea turtle: the loggerhead (Caretta caretta), green (Chelonia mydas), leatherback (Dermochelys coriacea), Kemp's ridley (Lepidochelys kempii) and hawksbill (Eretmochelys imbricata), according to the Florida Fish and Wildlife Conservation Commission. All of these species are considered endangered or threatened under the Endangered Species Act. The loggerhead is the most common species found nesting in the Boca Raton area of South Florida. 

Once a female loggerhead lays her nest, the eggs incubate in the sand for about 60 days until hatchlings emerge and make a desperate sprint across the beach to their ocean home. They hit the water and immediately swim several miles offshore to floating mats of seaweed known as sargassum, Welch said. 

Defenseless baby turtles find food and shelter in the seaweed for the first few years of their lives. And unfortunately, in addition to the small shrimp and other crustaceans the turtles find to eat in the sargassum, they find a wealth of bite-size pieces of plastic to feast on, Welch said. 

"Many of these young turtles are dying from plastic impaction. The plastic plugs them up and causes them to go into septic shock," center staff wrote in response to a comment on the Facebook post. "Plastic pollution is the sad world we live in now. We need to do better." 

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Originally published on Live Science.

The Yangtze giant softshell turtle (Rafetus swinhoei) is considered the most critically endangered turtle in the world, with only four known individuals left on Earth. On Saturday (April 13), that population fell to three, as the species' last known female died in a zoo in Suzhou, China, according to the BBC.

The captive turtle was more than 90 years old and died shortly after an attempt to artificially inseminate her, the BBC reported. No complications from the insemination procedure (which was the turtle's fifth) were reported, and the cause of death is being investigated.

The rare turtle is survived by one male, who also lives in the Suzhou Zoo and is believed to be about 100 years old. Scientists had been trying to breed the pair for years, a 2018 New Yorker article reported, but were unsuccessful due, in part, to the male's damaged penis.

The world's final two known R. swinhoei turtles live in separate ponds in Vietnam. Their genders are unknown. The species used to be widespread in the fresh waters of China and Vietnam, according to the New Yorker, but have dwindled to near-extinction due to hunting and habitat loss.

This is a sadly common story. According to a 2018 report from the Zoological Society of London, turtles and tortoises account for 29 of the world's 100 most endangered reptiles, "despite representing only 3.3% of reptilian species richness."

True to their names, Yangtze giant softshell turtles can be huge, growing to more than 360 lbs. (163 kg), the New Yorker reported.

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Originally published on Live Science.

When you hear the signature roars of Drogon, Rhaegal and Viserion — the three key dragon cast members in "Game of Thrones" — tortoise sex is probably the furthest thing from your mind. And yet, according to series sound designer Paula Fairfield, the mating cries of giant tortoises are among the many sound samples she used to give the show's great winged beasts a voice.

In a 2017 interview with RadioLab, Fairfield explained how she crafted the sounds of the dragons moving, roaring and communicating with other characters by mashing up various animal noises, including screeching birds and reptiles, fluttering dragonfly wings and even her own dog's nasal whistles. Listen closely to the way Drogon purrs in the company of his friends, and you may even hear a sound you'll wish you hadn't — the mating moan of a giant male tortoise. [Photos: 33 Stunning Locations Where 'Game of Thrones' Was Filmed]

First of all, yes, tortoises moan while they mate. The males, especially, are loud; Their mating groans can rattle on for 10 or 20 minutes, and can carry for miles around, James Gibbs, a conservation biologist at the SUNY College of Environmental Science and Forestry in Syracuse, New York, previously told Live Science. It's uncomfortable and a little funny to watch (here's a video if you're deathly curious), but a giant tortoise would probably say the same about your mating rituals.

So, why did Fairfield turn to this intimate corner of the reptilian soundscape for her dragon work? It's all a matter of imbuing each of the show's three dragon cast members with distinct personalities, she told RadioLab. Drogon, for example, is Daenerys' clear favorite. He is the rowdiest of the three, and yet the one Daenerys prefers to ride while flying about Westeros. He's even named after her "hot late husband" Khal Drogo, Fairfield said, so in a way "is like her lover."

"He's whistling at her all the time, he's whistling at her butt and saying, 'Ooh, baby,'" Fairfield said. "The groan of the male [tortoise] actually became, with some work and adjustments and stuff, the basis of Drogon's purr."

Fairfield added that the first time she watched the dragon-purring scenes with a larger audience, people couldn't help but giggle without knowing why. "To me, it's because [the purr] had that essence, that kind of sensual, sexual essence," Fairfield said.

You can listen for this tortoise essence while watching the final season of "Game of Thrones," which debuts Sunday (April 14).

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Originally published on Live Science.

Hundreds of millions of years ago, a shell-less turtle developed a malady in its bones. Now, 240 million years later, the Triassic period turtle is finally receiving a diagnosis: bone cancer. This is likely the oldest case of bone cancer ever found among reptiles, birds and mammals, according to the researchers who made the discovery and published their findings today (Feb. 7) in the journal JAMA Oncology.

Finding cancer in ancient bones is a "rather rare phenomenon," said study co-author Dr. Bruce Rothschild, a research associate at the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania. That's not because cancer didn't used to exist — in fact, it was likely as pervasive among ancient animals as it is today — but rather, spotting cancer in fossils is challenging without taking x-rays, Rothschild told Live Science. [Image Gallery: Fossilized Turtles Caught in the Act]

Using microscopy and computerized tomography — a type of X-ray — in collaboration with Rothschild, researchers over at the Museum of Natural History, Leibniz Institute for Research on Evolution and Biodiversity in Berlin, Germany imaged the fossilized left femur of the shell-less turtle, called Pappochelys rosinae. The bone had been discovered in southwestern Germany in 2013.

Pappochelys rosinae is an ancestor of modern-day turtles — other previously-found fossils suggested the reptile was only 8 inches long (20 centimeters), adorned with broad trunk ribs and had no shell. (Fully shelled turtles didn't appear until about 205 million to 210 million years ago, at least according to the fossil record).

The images revealed a mass in a layer of the bone called the periosteum. Sometimes it can be difficult to distinguish cancer from an infection in ancient bones, Rothschild noted. But the telltale signs of infection, such as pores where puss would have oozed out from, were absent in the femur.

Instead, what it looked like was a malignant periosteal osteosarcoma, a type of bone cancer, Rothschild said. This type of cancer has been previously reported in a Triassic amphibian, but this is likely the oldest instance found in an Triassic amniote, meaning a reptile, bird or mammal, the team reported.

What's more, the bone cancer seen in this ancient creature is pretty much what you'd see in a human today, Rothschild said.

"We are one community which responds to the environment and whatever factors that cause cancer in the same way," he said. "We're all part of the same Earth and we are all inflicted with the same phenomena."

• In Photos: Bones Reveal Ancient Sea Turtle
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• In Photos: Tagging Baby Sea Turtles

Originally published on Live Science.

The Year in Cute

2018 was a tough news year for a lot of us, but it was also a great year for the advancement of Cuteness Studies. In May, for example, scientists discovered that puppies reach peak cuteness at 6 to 8 weeks old. This is important information that will inform many lunchtime Google image searches for decades to come.

Elsewhere around the world, a donkey fell in love with an emu, a momma duck babysat 76 fluffy babies and penguins requisitioned a research camera to take selfies. Join us now for a photographic review of 2018's most adorable scientific moments. You've earned this.

A Very Smol Octopus

In 2018's top smol animal news, feast your peepers on this really, really, ridiculously tiny baby octopus.

This pea-sized cephalopod was spotted this August riding a piece of plastic litter in the ocean near Hawaii's Kaloko-Honokōhau National Historical Park. Park workers rescued the octo-baby from its debris boat, snapped a few pictures, then released it "safe and sound in a small protected space," the team wrote on Facebook. 

Smol as he is now, this little boi now has a chance to grow. While the baby is too young to identify as a precise species, similar-looking octopi can grow to have an armspan measuring up to 7 feet (2 meters). They grow up so fast!

When Penguins Pose

When you give a penguin a camera, it will try to take a selfie.

That was one of the (accidental) findings of a recent Antarctic research project, in which scientists left a live video camera perched near a rookery of emperor penguins. It didn't take long for the tuxedoed birds to find their watchers.

In the adorable footage that followed, the camera first focuses on the feet of two pudgy penguins as they waddle toward it — but the birds soon nudge the camera upward to focus on their faces. (And yes, even bird beaks look larger in selfies.) The penguins then make several vocalizations, as if to say, "Look what I found!" It turns out that even animals become a little vain when they know they're on camera (well, at least the best-dressed animals).

This Duck Supermom is Parenting Goals

One momma bird, 76 ducklings. Experts agree: That is one duckload of beaks to feed.

For what it's worth, this Minnesota supermom (dubbed 'Momma Merganser' by nature photographer Brent Cizek) definitely didn't lay all those eggs herself; mother ducks can incubate about 20 eggs at a time, ornithologist Richard Prum told The New York Times. The other ducks following momma may be enrollees in a sort of duckling day-care system called a crèche, in which female birds entrust their newborn young into the care of an older, wiser female.

This elder babysitter is usually experienced in raising young and doesn't mind taking a few hatchlings under her wing while the little tykes' parents go off to do important adult bird things, like molt their feathers. Still, while crèches of 20 or 30 ducklings are not uncommon, one bird with 76 followers is exceptional. The mystery of Momma Merganser remains one tough nut to quack.

Aye Aye, Captain!

How bizarre can a newborn look and still, somehow, be cute? Tonks the baby aye-aye may answer that question. Born at the Denver Zoo on Aug. 8, Tonks is one of only 24 of the nocturnal lemurs in captivity in the United States. She's a squirrel-size bundle of wiry fur, beady eyes and freakishly scraggly claws, and she's somehow still absolutely adorable.

Tonks is named after the "Harry Potter" character Nymphadora Tonks, a fitting moniker given that the newborn's mother is called Bellatrix, after the "Harry Potter" villain Bellatrix Lestrange. The new aye-aye's father, another Denver Zoo resident, is named Smeagol, after the dark-loving "Lord of the Rings" character. (Perhaps you can sense a theme here.)

Aye-ayes (Daubentonia madagascariensis) are native to Madagascar. No one knows precisely how many exist in the wild, but they are considered endangered. At the risk of sounding like a nosy mother-in-law, we hope Tonks carries on the family tradition of begetting healthy, literary-themed children.

The Donkey Who Loved an Emu

It was love at first… squawk-neigh?

Living on a farm in North Carolina, a donkey and emu named "Jack and Diane" have developed a deep bond with one another and appear to be in love. "They like to cuddle and even sleep together," Jennifer Gordon of the Carolina Waterfowl Rescue told The Charlotte Observer.

The Rescue discovered the unlikely couple when the farm's owner vanished in early November. When the cross-species lovers were put in separate pens, both showed signs of anger and anxiety (Jack, the donkey, reportedly started crying). They were promptly reunited — and hopefully they'll stay that way. Last we heard, the rescue team as currently looking for someone willing to adopt both a donkey and an emu. Could it be you??

When Elephants Eat Cereal

Elephants use their trunks to smell, touch and sometimes paint lovely little self-portraits. But how helpful is a trunk when it comes to eating tasty breakfast cereal?

In one of 2018's most adorable studies, scientists found out — with a lot of help from an African elephant named Kelly, who lives at Zoo Atlanta in Georgia. Researchers fed Kelly 24 plates of either chopped veggies or granular piles of bran cereal to see how the size of a meal changed the way Kelly used her trunk during feeding.

While Kelly picked up the veggies by scooping them into a tight bundle using the side of her trunk, the chalky piles of bran required a more tender approach. To eat the cereal, Kelly pressed her trunk onto the pile, pinched the tip of her trunk into a chopstick-like wedge and carried the captured pile of bran directly to her mouth. This research shows that elephant trunks are even more versatile tools than scientists previously knew — and also, elephants look really, really cute scooping up piles of treats.

The World's Punkiest Turtle

"The Mary River Turtle" would make a pretty good name for an '80s alt-rock band, but it happens to be the actual name of a tiny, green-mohawked turtle living in Australia. With whisker-like growths forking out of its chin and shocks of algae bursting off of its head like a punky green mohawk, the freshwater swimmer looks as much like an aging rocker as it does an endangered species.

Sadly, like many a rock star, this turtle is a dying breed. The rare turtle ranks 29th on a list of the world's 100 most endangered reptiles, released in April by the Zoological Society of London. One 2017 study estimated there may be as few as 136 of them left in the wild. The Zoological Society hopes to keep this number from plummeting by raising awareness of the cute, quirky creatures Earth stands to lose if habitats aren't properly protected from human encroachment.

A Brand-New Tardigrade with Spaghetti Eggs

Pinkish, pudgy and oh-so-smol, tardigrades — aka "water bears" — have a newborn baby cuteness about them that's hard to ignore, even when they're making poos half the size of their own bodies.

This year, a new species of tardigrade called Macrobiotus shonaicus was discovered in a parking lot in Japan. While it has the signature round, 8-legged body of all tardigrades, this newcomer has some of the weirder eggs researchers have seen. The spherical sacs are covered in wobbly, noodle-like filaments, possibly to help the egg attach to the surface where its laid. A new tardigrade with spaghetti eggs? We'll take it!

Tardigrades, in general, are famous for their toughness: They can survive in extreme cold (down to minus 328 degrees Fahrenheit, or minus 200 Celsius), extreme heat (more than 300 degrees F, or 149 degrees C), and even the unrelenting radiation and vacuum of space, as one 2008 study reported.

I Heard You Like Moons…

The moon is Earth's little buddy in the sky, but what if our moon had its own tiny companion to hang out with when the Earth was busy (say, during a total lunar eclipse)? We're talking about moonmoons — moons that orbit other moons.

Moonmoons (also known online as submoons, moonitos, grandmoons, moonettes and moooons) may not exist in our solar system or any other. However, according to a pair of astronomers writing in the preprint journal arXiv.org in October, the concept of a moon hosting its own mini-moon is, at least, plausible — so long as the host moon is sufficiently massive, the moonmoon is sufficiently small, and there is a wide orbital gulf between those moons and their host planet.

Whether humans will ever set foot on a moonmoon is hard to say. But if and when we do, it will truly be one (very) small step for man, and one giant leap for moonkind.

Originally published on Live Science.

The ancient cosmologers were right and Galileo was wrong: This turtle's got the whole freaking world on its back.

Live Science saw the above photo circulating on Twitter early last week and reached out to its originators — the good folks at Task Force Turtle — to get the full story behind it. That full story, it turns out, involves drugs, mysteries, amazing herpetological memories, butt gas and perhaps the ability to hold one's turtley breath for months on end.

The common snapping turtle in the image is one of a great number of snappers and painted turtles in the swamps of Maryland that Task Force Turtle — a project of herpetologists and undergraduate students at Washington College and other local institutions — has obsessively tracked over the course of the last decade-plus.

"All of our turtles, thousands of them now… have been fitted with radio transmitters in the summertime when they're making these movements [toward their winter mud holes]," Aaron R. Krochmal, a professor of biology at Washington College and one of the researchers who originated the project, said. "We follow them quite literally 24 hours a day."

The turtles in the area are interesting, he said, because they offer researchers the opportunity to study a migration in incredible detail. The turtles follow the same path, year after year, from their summer stomping grounds to their winter hideouts — tight packed, underground mud-holes where they can wait out the cold weather.

"What we think is super cool is that these animals do use a particular mud-place, if you will, a wallow. And they return each year to the same exact spot, and by exact spot I mean to the centimeter," Krochmal told Live Science.

That offers researchers an unusual opportunity to do a rigorous study of an annual migration, he said, getting up close and personal with the turtles in ways that just aren't possible with a herd of bison or Arctic terns on the move.

And the researchers do get quite up close and personal with their subjects, going so far as to mount "turtle-cams" on their backs to track their movements.

In the case of the turtle with the little living world on its back, Krochmal said, it hadn't actually just woken up from hibernation. Rather, she had just emerged from more than two weeks in the muddy earth by a lake that had dried up.

"We were actually not convinced that her radio transmitter was still attached," Krochmal said.

Most of the other turtles had moved on already toward their winter homes, and this one was deeply buried, showing no sign of emerging. Perhaps she'd gone already, managing to leave her transmitter behind.

But then the earth stirred, and, writhing, she emerged. Timothy Roth, a professor of psychology at Franklin and Marshall college snapped the picture.

The turtle, Krochmal said, weighs about 13 pounds (6 kilograms), and the 10-inch-thick (25 centimeters) world on her back weighed about 18 pounds (8 kg). But she began her journey toward her winter mud hole with no obvious sign of additional effort. [Top 10 Most Incredible Animal Journeys]

"She was just trucking right along," he said.

That tendency, to just follow the same path to the same mud hole year after year, is what draws Krochmal, Roth, and their colleagues to these creatures. It's just not known, he said, how common this sort of mud-hole migration is outside their area of Maryland. And it's a mystery exactly how the reptiles survive underground for months without coming up for air — though they may rely on pockets of air down there, and are known to slow their metabolic rates way down and gulp air bubbles through their mouths and cloacas (turtley anus-genital combination holes).

What the Turtle Task Force is slowly working out, however, is what it is in the critters' minds that lets them repeat such a specific journey every year, he said.

As part of that effort, he said, the team has dosed migrating turtles with a drug called scopolamine.

"What scopolamine does is it blocks the brain's ability to bind the neurotransmitter acetylcholine," he said.

That prevents the brain from forming or accessing memories. (In decades past, doctors administered it to women during childbirth, which is a whole other story.)

In migrating turtles, the researchers found, the drug causes them to lose their way.

"They just sort of wander in circles, as you might imagine, for about five or six hours until the drug wears off," Krochmal said. "Then they just sort of snap out of it, walk right back to their path, and continue along their path."

For the researchers, this is a story about how turtle brains process information to make their way back and forth across their little annual journey. For the turtles, it's a story of determination to continue going where you're going, no matter what chemicals some weird strangers inject into your body or what massive burdens you're carrying on your back.

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Originally published on Live Science.

A small pod of orcas (Orcinus orca) near the Galápagos Islands was caught on camera as they pushed, spun and dragged sea turtles around as if the turtles were pool toys. Orcas are known to play with their food before eating, but this was likely the first time they've been filmed tormenting sea turtles.

Nicolás Dávalos, a photographer and marine biology student in Ecuador, was in the area assisting with research when he and his colleagues spotted the group of orcas, also called killer whales, splashing around nearby.

"There was a lot of action and a lot of movement. Birds were flying around, so we thought [the orcas] were feeding," Dávalos said. The researchers hopped in a small boat and motored over to the orcas for a better look. [Photos: Drone Reveals Killer Whales]

It was clear that the orcas were chasing something, Dávalos said, "so I decided to go in the water." (Because what's there to fear from being in the water with one the ocean’s largest and most ferocious predators?)

Dávalos dove into the water with his snorkel and a GoPro. "At the beginning I was wary, but then I just felt the killer whales knew I was there," he said. "They turned around a few times to look at me, but they were totally fine with me being there."

The orcas, he said, seemed far more interested in entertaining themselves with the sea turtles than they were with him. "They would run away with their turtle, like a dog with a bone," Dávalos told Live Science. "They didn't want to share."

While this is probably the first time orcas have ever been caught on camera torturing helpless sea turtles, this kind of playful behavior is not unusual for the majestic carnivores.

"Killer whales will at times play with potential prey for a half hour or more, and then just move on, leaving the victim unharmed," Robert Pitman, a marine ecologist at the National Oceanic and Atmospheric Administration's Southwest Fisheries Science Center, told National Geographic.

"Other times, they will chase prey around and kill it but not eat it," Pitman said. "They're like cats in that way — can't resist the urge I guess."

"If you're a hunter, keeping a potential prey item alive for a long period of time — continually chasing down and catching it — is a good way to practice a lot of the skills that you might need later in life," Michael Weiss, a biologist and doctoral student at the Center for Whale Research, told National Geographic. Weiss added that younger orcas seem to play with their food more often than adults.

Very little is known about the orcas that frequent the Galápagos Island area, Dávalos said, which makes his encounter even more special. He hopes the video entices people to support ocean research and conservation efforts.

 "The oceans are full of opportunities to uncover beautiful and intricate mysteries," he said.  

Original article on Live Science.

Over a period of less than three weeks, more than 100 endangered sea turtles washed up dead on an 18-mile (30 kilometers) stretch of beach on the Pacific coast of Mexico near Guatemala, and authorities aren't sure why.

The mass mortality event began on July 24, when 26 dead turtles were discovered in the small tourist beach town of Puerto Arista in the state of Chiapas, Mexico's Federal Attorney for Environmental Protection (PROFEPA) reported. In the following days, officials recorded dozens more dead sea turtles in the area.

On Saturday (Aug. 18), PROFEPA reported that by Aug. 13, the number of dead turtles totaled 102 olive ridley sea turtles (Lepidochelys olivacea), six hawksbill sea turtles (Eretmochelys imbricate) and five Pacific black sea turtles (Chelonia mydas agassizii). All three species are classified by the Mexican government as critically endangered, PROFEPA reported. [In Photos: Tagging Baby Sea Turtles]

The dead turtles were all adults, including both males and females, and in various stages of decomposition. PROFEPA is performing necropsies on a few of the specimens and collecting tissue samples to help determine the cause of the deaths.

Wildlife experts suspect that some of the turtles died from interactions with fisheries operations in the area. Several of the turtles found on July 24 had injuries that appeared to come from a hooks or fishing nets, PROFEPA reported.

The coastal waters off Puerto Arista are part of a protected marine sanctuary, but sea turtles in the area are occasionally caught in legal fishing nets and drown. On Aug. 2, authorities met with fishers in the region and urged them to practice responsible fishing techniques that ensure protection of the endangered sea turtles, PROFEPA reported.

Authorities have also collected water samples in the area to test for the presence of harmful toxins from algae. On the Gulf Coast of Florida, a harmful algal bloom called a red tide has been responsible for the deaths of hundreds of fish, marine mammals and sea turtles. A similar algal toxin could be killing the sea turtles off the Pacific coast of Mexico, but authorities are still investigating, PROFEPA reported. 

Original article on Live Science.

Video recently shot in the Peruvian Amazon shows an astonishing sight: colorful butterflies drinking tears directly from the eyes of turtles basking by the river.

Phil Torres, a tropical entomologist and science communicator, was traveling down Peru's Tambopata River in early March when he spied the riverside scene and captured the footage, he told Live Science in an email. Three turtles had crawled onto branches by the riverbank to soak up the sun. And around their heads fluttered several species of brilliantly colored butterflies, swooping and settling near the turtles' eyes to delicately sip the reptiles' salty tears.

In a video, Torres described the tear-drinking butterflies as "one of the most bizarre, strange, beautiful, fascinating things I have ever seen in my entire life." He posted the footage to his YouTube channel, The Jungle Diaries, where he documents his research expeditions and discoveries. [Photos: Butterflies Drink Turtle Tears]

Those butterflies, about eight species from three different families, were all after the same thing: sodium, Torres explained in the video. Butterflies can't get sodium from flowers, so the insects have to seek it elsewhere. Some species of butterfly dive into poop as their sodium source; some find it in dirt, and others — like the butterflies by the river — target tears.

The tearful reptiles, likely yellow-spotted sideneck turtles (Podocnemis unifilis), belong to a group of turtles that can't retract their heads into their shells. Their only option for discouraging the thirsty insects is turning their heads from side to side, which isn't terribly effective, Torres told Live Science.

And butterflies that drink tears can be very persistent, targeting anything lying still enough and with its eyes open, he said.

"Heck, I bet if I laid out on a log long enough, they'd definitely come feed on my sweat (this is fairly common) and maybe even have a go at my eyes," Torres said.

Usually, turtles glimpsed in the Amazon dive back into the river as soon as a boat approaches, but Torres was able to film the group for about 10 minutes — probably because they were so distracted by the butterflies treating their faces like an all-you-can-drink happy hour.

"I'd say this is about a one-in-a-thousand turtle-basking event to get this lucky and see so many butterflies all around," Torres said.

Beneficial relationships

Some types of animals participate in a practice known as mutualism, a quid-pro-quo arrangement that usually involves two species trading services that benefit one another. For example, shaggy water buffalo that inhabit the wetlands of northern Turkey are often covered with tiny frogs that gobble up pesky flies on the bovines' backs. And cuckoo chicks, which are raised by other bird species, secrete a noxious chemical that keeps predators away from their foster families' nests.

However, while the Amazon butterflies are certainly getting something from the turtles, it's less clear how the turtles benefit from the arrangement, Torres told Live Science.

"They definitely don't seem to enjoy it," he said. "This is a fairly colorful example of commensalism — a species partnership where one species benefits and the other species doesn't really get affected, positively or negatively."

Original article on Live Science.

The Mary River turtle doesn't take its name from '80s alt-rock icons The Jesus and Mary Chain, though we wouldn't fault you for the guess. With whisker-like growths forking out of its chin and shocks of algae bursting off of its head like a punky green mohawk, the freshwater swimmer looks as much like an aging rocker as it does an endangered species.

The Mary River turtle (Elusor macrurus) is actually named for the Mary River in Queensland, Australia, which is the only place on Earth where it lives. The rare turtle ranks 29th on a new list of the world's 100 most endangered reptiles, released last week (April 10) by the Zoological Society of London (ZSL).

The new list is part of the ZSL's EDGE of Existence program (EDGE is an acronym for "Evolutionarily Distinct and Globally Endangered" species), which casts a spotlight on some of the world's most unique and extinction-prone species that live far out on their own branches of the tree of life.

Species like the Mary River turtle have few close relatives on Earth; according to the EDGE website, these turtles diverged from all other living species around 40 million years ago. As such, they "represent a unique and irreplaceable part of the world's natural heritage" that is at risk of being lost forever; one 2017 study estimated there may be as few as 136 of them left in the wild. The aim of EDGE is to increase awareness and protection of these far-out creatures before it's too late.

The Mary River turtle has emerged as an unofficial poster child for the list of rare reptiles, thanks mainly to its irresistibly odd appearance. In addition to its algae-engulfed body, the turtle has some biological bona fides. For one, it can breathe out of gill-like glands in its cloaca — the multipurpose orifice many reptiles use for both excretion and mating — and can thus stay underwater for up to three days, according to EDGE.

Turtles and tortoises account for "29 of the top 100 EDGE reptiles, despite representing only 3.3 percent of reptilian species richness," the researchers wrote in a new study, published online April 11 in the journal PLOS ONE, that accompanies the list. The top spot on the reptile list goes to the Madagascar big-headed turtle, a prehistoric-looking, sometimes rainbow-tinted reptile whose lineage stretches back 80 million years. The species is critically endangered, but conservation efforts are underway, EDGE reported.

Originally published on Live Science.

The climate is changing, and so are the turtles.

A study published yesterday (Jan. 8) in the journal Current Biology about green sea turtles that nest along island beaches near Australia's Great Barrier Reef found that turtles born in areas most heated by climate change are 99.8 percent female. Turtles born farther south, along a cooler beach, are only about 65 percent female.

The result isn't surprising if you know a bit about turtle biology, but it is alarming. Sea turtles, like these green sea turtles (Chelonia mydas), don't have genetically determined sexes, the way mammals do. Instead, the researchers wrote, "In sea turtles, cooler temperatures produce more male hatchlings while warmer temperatures produce more females."

An egg in hot sand is more likely to produce a female turtle, and an egg in cool sand is more likely to produce a male. [In Photos: Tagging Baby Sea Turtles]

The pivot temperature where a population will turn out 50 percent females and 50 percent males is based on genetics and varies with species and even individual nesting groups, the researchers wrote. Turtles  seem to target their breeding periods to times when the sand is slightly warmer than their pivot temperatures, resulting in populations moderately skewed female. But shift the temperature of that period just a few degrees and the resulting baby turtles will be not just a bit female — instead, hardly a male will appear in the whole group.

Due to climate change, Raine Island — the site of the key breeding ground in this study — has warmed significantly since the 1990s, the researchers wrote, likely accounting for the hard female skew.

So, the researchers developed a new technique: Studying the turtles' hormones.Proving that the increasing temperatures actually changed the turtle population proved challenging, though. Turtles don't wear signs of their sex as obviously as humans; researchers can't tell just by looking between their legs. And the easiest method — cutting them open — isn't really an ethical way to approach an endangered turtle population.

A genetic test won't offer any insight into a given turtle's sex, since sea turtles don't carry their sexes in their genetic code. But the researchers found that if they brought blood plasma samples back to their lab, they could use hormonal differences to distinguish male and female turtles.

It's not clear yet, the researcher wrote, how exactly the wild female swing will impact the sea turtles' future. Males breed far more often than females, but researchers don't know to what extent the handful remaining can make up for all their missing brothers. It's also possible, the researchers wrote, that females will seek out mates in cooler climates to the south.

"Our study highlights the need for immediate management strategies aimed at lowering incubation temperatures at key rookeries," the researchers wrote, "to boost the ability of local turtle populations to adapt to the changing environment and avoid a population collapse — or even extinction."

Originally published on Live Science.

This article was originally published at The Conversation. The publication contributed the article to Live Science's Expert Voices: Op-Ed & Insights.

To breathe or not to breathe, that is the question.

What would happen if you were submerged in a pond where the water temperature hovered just above freezing and the surface was capped by a lid of ice for 100 days?

Well, obviously you'd die.

And that's because you're not as cool as a turtle. And by cool I don't just mean amazing, I mean literally cool, as in cold. Plus, you can't breathe through your butt.

But turtles can, which is just one of the many reasons that turtles are truly awesome.

Cold weather slow down

As an ectotherm — an animal that relies on an external source of heat — a turtle's body temperature tracks that of its environment. If the pond water is 1℃, so is the turtle's body.

But turtles have lungs and they breathe air. So, how is it possible for them to survive in a frigid pond with a lid of ice that prevents them from coming up for air? The answer lies in the relationship between body temperature and metabolism.

A cold turtle in cold water has a slow metabolism. The colder it gets, the slower its metabolism, which translates into lower energy and oxygen demands.

When turtles hibernate, they rely on stored energy and uptake oxygen from the pond water by moving it across body surfaces that are flush with blood vessels. In this way, they can get enough oxygen to support their minimal needs without using their lungs. Turtles have one area that is especially well vascularized — their butts.

See, I wasn't kidding, turtles really can breathe through their butts. (The technical term is cloacal respiration.)

Not frozen, just cold

We are not turtles. We are endotherms — expensive metabolic heat furnaces — that need to constantly fuel our bodies with food to generate body heat and maintain a constant temperature to stay alive and well.

When it's cold out, we pile on clothes to trap metabolic heat and stay warm. We could never pick up enough oxygen across our vascularized surfaces, other than our lungs, to supply the high demand of our metabolic furnaces.

For humans, a change in body temperature is a sign of illness, that something is wrong. When a turtle's body temperature changes, it's simply because the environment has become warmer or colder.

But even ectotherms have their limits. With very few exceptions (e.g., box turtles), adult turtles cannot survive freezing temperatures; they cannot survive having ice crystals in their bodies. This is why freshwater turtles hibernate in water, where their body temperatures remain relatively stable and will not go below freezing.

Water acts as a temperature buffer; it has a high specific heat, which means it takes a lot of energy to change water temperature. Pond water temperatures remain quite stable over the winter and an ectotherm sitting in that water will have a similarly stable body temperature. Air, on the other hand, has a low specific heat so its temperature fluctuates, and gets too cold for turtle survival.

Crampy muscles

An ice-covered pond presents two problems for turtles: they can't surface to take a breath, and little new oxygen gets into the water. On top of that, there are other critters in the pond consuming the oxygen that was produced by aquatic plants during the summer.

Over the winter, as the oxygen is used up, the pond becomes hypoxic (low oxygen content) or anoxic (depleted of oxygen). Some turtles can handle water with low oxygen content — others cannot.

Snapping turtles and painted turtles tolerate this stressful situation by switching their metabolism to one that doesn't require oxygen. This ability is amazing, but can be dangerous, even lethal, if it goes on for too long, because acids build up in their tissues as a result of this metabolic switch.

But how long is "too long?" Both snapping turtles and painted turtles can survive forced submergence at cold water temperatures in the lab for well over 100 days. Painted turtles are the kings of anoxia-tolerance. They mobilize calcium from their shells to neutralize the acid, in much the same way we take calcium-containing antacids for heartburn.

In the spring, when anaerobic turtles emerge from hibernation, they are basically one big muscle cramp. It's like when you go for a hard run — your body switches to anaerobic metabolism, lactic acid builds up and you get a cramp. The turtles are desperate to bask in the sun to increase their body temperature, to fire up their metabolism and eliminate these acidic by-products.

And it's hard to move when they're that crampy, making them vulnerable to predators and other hazards. Spring emergence can be a dangerous time for these lethargic turtles.

Cold weather turtle tracking

Field biologists tend to do their research during the spring and summer, when animals are most active. But in Ontario, where the winters are long, many turtle species are inactive for half of their lives.

Understanding what they do and need during winter is essential to their conservation and habitat protection, especially given that two-thirds of turtle species are at risk of extinction.

My research group has monitored several species of freshwater turtles during their hibernation. We attach tiny devices to the turtles' shells that measure temperature and allow us to follow them under the ice.

We've found that all species choose to hibernate in wetland locations that hover just above freezing, that they move around under the ice, hibernate in groups and return to the same places winter after winter.

Despite all this work, we still know so little about this part of turtles' lives.

So, I do what any committed biologist would do: I send my students out to do field research at -25℃. We are not restricted to fair-weather biology here.

Besides, there is unparalleled beauty in a Canadian winter landscape, especially when you envision all of those awesome turtles beneath the ice, breathing through their butts.

Jacqueline Litzgus, Professor, Department of Biology, Laurentian University

This article was originally published on The Conversation. Read the original article.

An extraordinarily well-preserved fossil of a baby sea turtle that lived 54 million years ago contains traces of dark pigments that would have acted as built-in sunscreen, protecting the animal from the sun's harmful ultraviolet (UV) radiation.

The specimen, which is among the best-preserved fossils of sea turtles in the world, includes soft tissue, and analysis identified molecules linked to color, muscle contraction and oxygen transport in the blood, researchers reported in a new study.

One molecule in particular — eumelanin, a pigment linked to dark skin color in humans — hinted that the ancient turtle's shell contained dark colors, perhaps in patterns such as those found in sea turtles alive today, the study authors wrote. [Image Gallery: 25 Amazing Ancient Beasts]

Found in 2008 entombed in fine-grain limestone in a marine deposit in Denmark, the fossil is very small — about 3 inches (74 millimeters) long, and many of the bones retain their original shape in three dimensions. The reason the fossil is in such good condition is likely that the turtle's remains were trapped within a hard, rocky mass of sediment very early in the fossilization process, the study's lead author, Johan Lindgren, a senior lecturer with the Department of Geology at Lund University in Sweden, told Live Science in an email.

After much of the fossil mineralized, protecting remnants of soft tissue, the absence of extreme heat or cold would have prevented any remaining soft tissue from degrading further, Lindgren explained.  

The scientists evaluated five samples of soft tissue from a sublayer in the turtle's shoulder area, which was revealed during a second stage of fossil cleaning and preparation in 2013. When the researchers probed the tissue samples, they noted "a dark, well-defined film" containing structures that were carbon-rich, and which may have held organic compounds, they reported in the study.

The researchers analyzed the film using a combination of imaging and chemical techniques, which allowed them to identify molecules and determine their precise locations within the fossil — specifically, in organic material that once made up the turtle's skin and shell, Lindgren told Live Science.

Molecules of eumelanin revealed to the scientists that the turtles were pigmented with dark patches, much like the dark patterns seen on the backs of modern sea turtles, the study authors wrote. Patterns with dark coloration are known to protect sea turtles from UV rays and also help young turtles retain heat, which can enable them to grow faster. This biological feature is known as adaptive melanism — coloration that improves the turtles' chances for survival — and the researchers' findings suggest that this adaptation may have emerged in the turtle lineage as early as 54 million years ago, according to the study.

Scientists have examined fossilized plants and animals for centuries, yet there is still much to be discovered about how living organisms are preserved for millions of years, and how much of their biological makeup may be retained after fossilization, Lindgren told Live Science.

"Despite many years of research, we still have an incomplete understanding of what can be retained in the fossil record and exactly how the fossilization process works," Lindgren said.

The findings were published online Oct. 17 in the journal Nature: Scientific Reports.

Original article on Live Science.

American West

Theodore Roosevelt once wrote of the American West that "nowhere, not even at sea, does a man feel more lonely than when riding over the far-reaching, seemingly never-ending plains." These desert lands of faraway horizons dotted with the spectacular mountain ranges often look desolate, but in truth, they teem with many unique species of plants and animals.

Awesome animal

One such amazing critter of the American West is the desert tortoise. These large, herbivorous reptiles can be found slowly plodding across the dry desert landscapes of the West. Their most preferred plant community in which to live is that of the creosote bush, Larrea tridentata, regions but they can also thrive in succulent scrub, microphyll woodland, saltbush and semi-desert grassland areas. There are two species of desert tortoises found in the West: the Mojave Desert Tortoise, Gopherus agassizii and the Sonoran Desert Tortoise, Gopherus morafkai.

Across the west

The range of the desert tortoise is located across the Mojave and Sonoran Deserts in the states of Utah, Nevada, California and Arizona, as well as within the Sonoran Desert region of western Mexico, They can live at elevations ranging from below sea level (like Death Valley) to high dry desert regions upwards of 7,300 feet (2,225 meters). They seems to prosper best at elevations that range from 1,000 feet (305 m) to 3,000 feet (914 m).

Built-in camo

The high-domed carapace of the desert tortoise can reach a length of 8 to 16 inches (20 to 40 cm) and a height of 4 to 6 inches (10 to 15 cm). The color of the shell tends to be greenish-tan to dark brown in color, perfect for blending into the predominately brown desert landscape. A mature adult tortoise will weigh between 8 and 20 pounds (3.6 to 9 kilograms). A desert tortoise can live upwards of 60 to 80 years.

Built for the desert

The desert tortoise is equipped with powerful legs and thick, flattened claws ideal for digging. The front legs are covered with a thick layer of protective, tough scales. The hind legs are more stumpy and elephantine in appearance. The feet of the desert tortoise are also web-less. The desert tortoise is a member of the Family Testudinidae, a family consisting of only 5 species in all of North America.

Survival skills

Desert tortoises survive well in the hot desert environments in which they live. Their powerful front legs can easily dig underground burrows 3 to 6 feet (0.9-1.8 m) in length, from which the tortoise can escape ground temperatures that can soar to more than 140 degrees Fahrenheit. (60 degrees Celsius). Desert tortoises are said to be ectothermic, meaning they control their body temperature by using an underground burrow. The burrow protects the tortoise from both the summer heat and winter cold found in the American deserts.

Homebody

The desert tortoise spends upward of 98 percent of its time in its underground burrow, making it one of the most elusive creatures of the desert. During a normal year of temperatures, it will spend from November to February in a torpid, or hibernation, state while in its underground burrow. The home range of a desert tortoise is thus limited to a desert area where these life-saving burrows can be dug into the rocky desert soil.

Out and about

By early March, the warmth of the mild desert spring returns and the desert tortoise emerges from hibernation. The desert tortoise is most active during the spring and early summer, foraging on the many wildflowers and tender plants that now cover the desert floor. A desert tortoise requires 15 to 20 years to become sexually mature. Mating season arrives in early summer with aggressive male-to-male combat. A dominant male may win the chance to mate, but it appears that a female does have some choice in the matter.

Baby time

A fertile female will lay a clutch of 3 to 12 eggs in a nest in or near her burrow's entrance. The eggs go unattended and will begin to hatch at the end of the rainy season in September and early October, after an incubation period of 90 to 120 days. The 2- to 3-inch-long (5 to 7 cm) hatchlings now have a soft shell and are very susceptible to predators, such as ravens, hawks coyotes, foxes and bobcats. Scientists estimate that only about 2 percent of desert tortoise hatchlings survive to become adults.

Snack time

The summer monsoon season across these dry desert lands result in a burst of vegetation growth and is the prime feeding season for the desert tortoise, when it will eat most of its yearly supply of food. They will eat leaves, stems, flowers and fruits of many species of desert plants. Because of a special type of bacteria that lives in its digestive system, the desert tortoise can digest many species of plants that are not edible for other desert wildlife.

Unique skills

An adaptation to desert life that the desert tortoise has successfully made is the unique ability to extract from the plants that they eat almost all the water they require in order to survive. If free-standing water is available, such as after a monsoon shower, the tortoise will drink it but can survive many months from the moisture it acquires from its food. They will also store water in their bladder, reabsorbing the water back into its systems during periods of extended drought.

Flipping defense

The desert tortoise is usually a solitary animal, except during mating season. Then, both male and female tortoises of the same sex will fight each other when they cross paths. Males are especially combative at this time and use a structure known as a gulag scute, which grows outward under their neck from their shell, to ram and flip over a potential male rival. A flipped male has not only lost the battle but if he cannot right himself, he will die from the heat of the desert sun.

Losing habitat

Like many species of wildlife, the greatest threat to the desert tortoise is loss of habitat due to human activity and development. In some areas of the American deserts, the desert tortoise population has decreased by 90 percent. Vehicle traffic both on highways and on the open desert are especially damaging to the tortoise population. In the Western Mojave Desert, a study showed that the desert tortoise population is, on average, 200 adults per square mile. Today, that number is thought to be just five to 60 adults per square mile.

Adapting to life

The deserts of North America are inhabited by many species of plants and animals that have adapted well to the extreme temperatures and dry conditions found across this vast landscape. The desert tortoise is just one such splendid example of life's ability to acclimate to any environment. Conservation projects are ongoing in the United States and Mexico to assure that the desert tortoise is a part of this amazing desert ecosystem forever.

The aptly-name red-eared slider is an easily recognizable semiaquatic turtle that's popular in the global pet trade. These animals are considered one of the top invasive species of the world, and it's really no wonder when you consider their mating habits.  

Red-eared sliders (Trachemys scripta elegans), which have a red stripe around their ears and are known to quickly "slide" off objects into the water, are native to the southern United States and northern Mexico. But thanks to the global pet trade industry, they're the most widespread turtle species, having been introduced to dozens of countries, said Greg Pauly, a herpetologist at the Natural History Museum of Los Angeles County.

Though the reptiles are desired as pets for their initial small size and low maintenance, some pet owners face a rude awakening: The turtles get bigger. "The turtle may have only required a 2-gallon tank when you bought it, but after a few years it needs a 100-gallon tank or a backyard pond," Pauly told Live Science. "They're also kind of messy and kind of stinky. So, after a few years [of growth], they become a big commitment." [In Photos: The World's Freakiest Looking Animals]

Some owners take the easy way out by releasing their red-eared sliders into the wild, helping the turtles spread to the urban ponds, streams and reservoirs of every continent save for Antarctica.

In these habitats, male red-eared sliders will engage in courtship behaviors as long as it's warm enough for them to swim around. "They are pretty single-minded in focus," Pauly said, adding that the age at which the animals begin mating depends on their location. In the warmest of climates, males may reach sexual maturity at 2 year old and females 3 to 4 years old; the animals become sexually active a few years later when in colder climates.

Compared with females, male red-eared sliders have extra-long claws on their forefeet. But rather than use these claws as weapons, "Nightmare on Elm Street" style, males use their claws more like jazz hands to woo females.

When a male finds a female, he will swim up close to her, bring his forelimbs forward, and wave or rapidly vibrate his claws in front of her face. He may also use his claws to "tickle" the female's face, Pauly said.

If the female is uninterested, she'll try to avoid the male and swim around him or past him. But often, she won't get very far without running into another male. "The females are harassed constantly by all these males that are courting them," Pauly said.

Sometimes, the female will decide she's had enough and will pull her head down into her shell. But males, especially the older ones, don't always take "no" for an answer and may bite at the large fold of skin around the female's skin that's still sticking out, possibly wounding her.

It's not clear how females choose mates, if they have any choice at all.

But if the female is receptive, she'll allow the male to climb onto her back while the pair are still in the water. The male will use his forelimbs to hold onto her shell and his backlimbs to brace himself as his tries to position his cloaca (waste and reproductive orifice) as close to hers as possible.

Male red-eared sliders, like other turtles, have a large penis to body size ratio. During mating, the cloaca everts and engorges through hydrostatic pressure to become a penis that's 30 to 40 percent of the length of the turtle's body. Unlike the mammalian penis, which has a tube to transfer sperm, the turtle's penis has a channel-like groove that the sperm moves down.

Much of the male's exceedingly long penis goes into the female during copulation, which lasts up to 15 minutes.

After mating, females may store the male's sperm for an extended period of time before deciding to use it to fertilize her eggs. In fact, she could mate again and use the sperm of multiple males for a single clutch. 

"For turtles, red-eared sliders are surprisingly prolific," Pauly said. That is, a female will lay up to 30 eggs in a terrestrial nest. And if the conditions are right, she may lay up to five or six clutches in a single year.

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