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."

Researchers have unearthed the oldest pterosaur ever discovered in North America and named it the "ash-winged dawn goddess."

The 209 million-year-old pterosaur was among a cache of more than 1,000 Triassic fossils extracted from rocks in the Petrified Forest National Park in Arizona. Eotephradactylus mcintireae is partly named after volcanic ash found in the fossil bed and Eos, the Greek goddess of the dawn, because it evolved near the beginning, or dawn, of pterosaurs' evolutionary history.

Pterosaurs, informally called "pterodactyls," were flying reptiles that dominated the skies during the age of dinosaurs. The group produced many giants, some with wingspans stretching to around 36 feet (11 meters), but E. mcintireae and the other early members were tiny by comparison.

"This pterosaur would be the size of a small seagull, and could have sat on your shoulder," study lead author Ben Kligman, a paleontologist at the Smithsonian's National Museum of Natural History in Washington, D.C., told Live Science in an email.

E. mcintireae was just one member of a lost ecosystem described in the study, published Monday (July 7) in the journal PNAS. The cache of Arizona fossils also included giant amphibians, freshwater sharks, armored crocodile-like creatures and one of the oldest known turtle fossils.

These finds help researchers understand what animals were alive before the violent mass extinction event, likely triggered by volcanic eruptions, that brought the Triassic period to a close around 201 million years ago.

Related: Giant pterosaurs weren't only good at flying, they could walk among dinosaurs too

Towards the end of the Triassic, northeastern Arizona was located just above the equator in the middle of the supercontinent Pangaea. At the time, the semi-arid landscape was marked with small rivers and channels that were likely prone to flooding, according to a statement released by the Smithsonian. Researchers suspect that a flood washed over the tiny pterosaur and other animals living in the region at the time, burying their bodies in sediment and ash.

A team of scientists first discovered what remained of the Triassic bonebed in 2011. The fossils were mostly small and delicate, so rather than trying to excavate them in the field, the team extracted large chunks of sediment and worked through them in labs. Many chunks went to the Smithsonian National Museum of Natural History, where volunteers spent thousands of hours carefully extracting the fossils. A volunteer named Suzanne McIntire extracted a jaw belonging to the pterosaur in 2013 — the species name mcintireae honors her discovery.

Kligman began working on the fossils in 2018, after the jaw had been discovered, and said he doubted the fossil was a pterosaur at first — at the time, researchers had only found one early pterosaur in North America, and none had ever been found in sediment deposited in a river.

"When I finally examined the jaw my doubts were put to rest — the distinctive teeth and jaw anatomy was unmistakably from a pterosaur," Kligman said. "I was most surprised by the fact that a delicate, tiny jaw like this one had not been destroyed by the movement of river gravel prior to it being fossilized, suggesting that the bonebed was preserving a unique fossilization setting."

The bonebed revealed a community of evolutionary newcomers, such as pterosaurs and turtles, sharing the landscape with each other and more ancient animals, such as giant amphibians, before the latter went extinct at the end of the Triassic.

"The presence of the pterosaur Eotephradactylus living and interacting in a community alongside groups like frogs, lizard relatives, and turtles is the first occurrence of this community type in the fossil record — these groups are commonly found living together in post-Triassic communities from the Jurassic and Cretaceous, however they had never been found together preceding the end-Triassic extinction event 201 million years ago," Kligman said.

Animals come in all shapes and sizes, and many have iconic features that make them memorable. From the long necks of giraffes to the oddly shaped heads of hammerhead sharks, here's how 10 remarkable animals evolved their signature features.

Related: How long do new species take to evolve?

1. Turtle shells

For years, scientists debated how turtle shells evolved. According to a report published in the journal Current Biology, paleontologists once believed that the shell was formed through the fusion of osteoderms — bony deposits that make up the protective scales on crocodiles and armadillos. But developmental biologists disagreed with this theory, given how the embryos of modern day turtles develop. Instead, they believed the ribs underneath turtle ancestors' bodies fused and gradually united over the body to form the shell.

The debate wasn't settled until 2008, when Chinese scientists discovered the fossil of Odontochelys semitestacea, whose name means "half shelled turtle with teeth." Although the fossilized animal's shell was incomplete, it had no osteoderms and showed widening of the ribs, confirming the developmental biologists' theory. Scientists say it represents an intermediate step in the evolution of the turtle shell. The later stages of evolution are shown in fossils of the genus Proganochelys.

2. Giraffes' long necks

Giraffes' necks can be up to 10 feet (3 meters) long, allowing the animals to reach leaves high up in trees. But they didn't always have this impressive feature.

Discokeryx xiezhi is a sheep-size, ancient relative of modern day giraffes that lived around 17 million years ago during the the early Miocene epoch (23 million to 5.3 million years ago). It had a stumpy neck and a disk-shaped, thick skull. Scientists in 2022 proposed that the thick skulls of D. xiezhi evolved to withstand massive blows to the head during fights between males. Those same bouts fueled the growth of their necks to aid in fighting. This is called the "necks for sex" hypothesis and suggests competition led to longer necks developing. Males who won fights more often passed these genes onto their offspring than did the losers, eventually leading to the giraffes we see today.

3. Elephant tusks

Elephants have deeply rooted tusks protruding from their mouths that grow continuously. These tusks are actually enormous teeth that give the pachyderms an evolutionary advantage when digging, lifting objects, stripping bark of trees and protecting themselves.

The earliest known tusks are found in Dicynodonts, a group of stocky, pig-like herbivores that lived 270 million years ago and had unique pointed beaks with protruding teeth on either side.

Members of this clade with true tusks were also missing several teeth. Researchers theorized that it may have been more energetically favorable to develop tusks that continuously grow, rather than replacing teeth that may have fallen out. They also suggested that the tusks evolved independently in different populations over time. When the tusks developed, soft tissue ligaments formed, anchoring the large teeth to the jaw.

4. Blue whales' gigantic size

Blue whales (Balaenoptera musculus) are the biggest animals to have ever lived. Their size makes it hard to believe the mammoth sea mammals evolved from a dog-sized ancestor, Pakicetus. According to a 2016 study in the journal Biology Letters, the size of baleen whales, including the blue whale, grew significantly over the last 5.3 million years.

One of the main reasons for this accelerated growth is the filter-feeding behavior of baleen whales, which use bristle-like teeth to sieve plankton from the ocean. This somewhat "passive" feeding strategy is tied to a highly efficient metabolism which allows the whales to conserve large amounts of energy while traveling long distances.

Researchers believe the explosive growth of baleen whales started in the Pleistocene epoch (2.6 million to 11,700 years ago). Nutrient dense runoff from the ice spilled into the ocean, creating dense patches of plankton and krill. The high productivity of the ocean combined with the low energy-using whales drove a massive growth spurt in the animals, allowing them to reach the colossal sizes we see today.

5. Tigers' stripes

Tiger stripes vary between individuals, much like fingerprints in humans. The markings play an important role in helping a tiger remain hidden while hunting prey. The stripes help break up the shape of the animal's body, allowing it to blend in with tall grass.

In 1952, the British Mathematician Alan Turing theorized that a chemical reaction between two homogeneous substances were responsible for the famous tiger-stripe pattern, along with other patterns commonly found in nature. He dubbed these substances "morphogens." One acted as an "activator" and the other as an "inhibitor" — with the "activator" causing a stripe to form and the "inhibitor" creating a blank space.

In 2012, a study in the journal Nature Genetics experimentally validated this theory by identifying the morphogens at play in the formation of ridge patterns in the mouths of mice.

6. Head of a hammerhead shark

Hammerhead sharks famously have distinct hammer-shaped heads, with beady eyes at each end. Ancestors of the hammerheads alive today first appeared 20 million years ago.

It was assumed that the evolution of the hammer-head evolved from a 'normal shaped head', so from sharks with a more rounded head that gradually elongated over time into much larger sharks where the head is even more defined.

In 2010, a DNA analysis of eight species of hammerhead sharks alive today and of varying sizes revealed that ancestors of hammerheads were very large, around 6.5 feet (2 m) long. Scientists hypothesized that modern hammerheads' unusually shaped heads came from larger individuals and only later showed up in smaller bodied hammerheads, like the bonnethead (Sphyrna tiburo), as they evolved.

Few theories exist to explain the function of hammerheads' unusual head shape and why it evolved this way. Some suggest it improves maneuverability, helps the sharks capture prey and even may enhance their sense of smell. In a study published in December 2023 in the Journal of Experimental Biology, scientists showed that the sharks' wide heads give them better binocular vision, depth perception and stereovision than a slimmer-headed shark.

7. Rattlesnake rattle

The sound of a rattlesnake's tail sends chills down the spine of anyone that hears it. The noise-making rattle on the tail is made of hollow caps of keratin that loosely interlock, making sound when the snake shakes its tail.

In a2016 study in the journal The American Naturalist, scientists looked at 56 snake species from the families Viperidae (which includes rattlesnakes) and Colubridae (one of the largest snake families). When exposed to a possible threat, snakes from both families began shaking and vibrating the ends of their tails, suggesting a shared origin of this behavior. The species more closely related to rattlesnakes also shared similarities in the duration and rate of tail vibration.

The researchers behind this study suggested that this widespread snake behavior may have served as "the signal precursor to rattlesnake rattling behavior." Snakes that shook their tails fastest may have developed callus at the end of their tails to serve as a better warning signal to predators, with this eventually leading to the creation of the rattle.

8. Hummingbirds' long bills 

The smallest birds in the world, hummingbirds are known for their bright colors and long bills that help reach nectar in flowers. Hummingbirds split from swifts — insect-eating birds that have shorter and wider beaks — in Europe 42 million years ago. They then appeared in South America around 22 million years ago , having evolved a unique taste receptor for sweetness. They also developed a taste for nectar, according to a 2014 study published in the journal Science.

As a result, hummingbird bills evolved to better feed on different flower species, and competition boosted diversity in bill length and shape.

9. Lobster claws

Lobster-like crustaceans first appeared around 400 million years ago. The modern creatures have strikingly large, asymmetrical claws with the larger one being dominant, similar to how humans are either right-handed or left-handed.

Adult lobsters develop a cutter claw with fast fiber muscles that  can snap at a speed of 20 milliseconds to help tear and cut their food. Their other claw is a short and heavy crusher claw. The crusher claw muscle is made up of slow muscle fibers that can exert a powerful pressure of 100 pounds per square inch.

Juvenile lobster claws, on the other hand, are symmetrical and slowly change over time as the animals get bigger. The claws gradually change in response to how they are being used.

Clawed lobsters first showed left and right-handedness from the Early Triassic. Theories suggest that this adaptation helped lobsters pry open or crush shelled-creatures during the time of the Mesozoic Marine Revolution — a period of time between the Triassic (247.2 and 242 million years ago) and the end of the Cretaceous (66 million years ago) during which marine animals evolved new ways of preying on shellfish and there was increased competition for food between predators.

10. Pelican beak pouches

Pelicans are large water birds, known for their long beaks and large throat pouches that help them consume up to 4 pounds (1.8 kg) of fish per day. They scoop buckets of water, trapping the fish inside its beak.

How this handy tool evolved is a mystery because beak and bill fossils are rarely found from birds that lived in the Paleogene era (between 66 million and 23 million years ago). That changed in 2010, when the earliest known pelican fossil was found with an almost completely preserved beak. The pouches of the pelican have changed minimally over  the last 30 million years, the researchers found.

Pelicans can eat a massive amount of food thanks to their pouches, so the study authors think this is why they evolved.

The beauty and majesty of rainbows have inspired awe in humans for millennia, but it wasn't until Isaac Newton's groundbreaking work unlocking the secrets of light did we truly begin to understand how they form.

In this extract from the new book "Beautiful Experiments: An Illustrated History of Experimental Science" (The University of Chicago Press, 2023), science writer Philip Ball explains how Isaac Newton's ingenious experiment with prisms transformed our understanding of light.

The puzzle of the rainbow was resolved in the seventeenth century through the work of the scientist who some regard as the greatest ever to have lived. In 1666, Isaac Newton — then a 23-year-old Cambridge graduate — performed an experiment with light that transformed our understanding of it. 

While it was thought that the bar of rainbow colors — called a spectrum — produced when white light (like sunlight) travels through a glass prism is caused by some property of the prism that alters the light, Newton showed the colors are already inherent in the light itself. Legend has it that Newton did the experiment at his family home in Woolsthorpe, Lincolnshire, to which he had returned to escape the Great Plague that ravaged England in 1665. 

It did not, after all, require any fancy apparatus — just a few prisms, which could be bought almost as trinkets at markets (although he needed good-quality ones!). While there's truth in that, Newton had been planning such experiments for a while in his Cambridge room: we need not credit the plague for stimulating this leap in understanding optics. Newton didn't report his results until six years later, when he sent an account to the Royal Society in London, the intellectual center of "experimental philosophy" in the mid-century. 

Related: 9 equations that changed the world

He was famously reluctant to disclose the outcomes of his studies, and had to be cajoled into writing down his celebrated laws of motion and theories about the motions of the planets in his masterwork the Principia Mathematica in 1687. The book in which he recorded his experiments and theories about light, Opticks, was finally published in 1704. This was not so much because Newton was diffident about his work; on the contrary, he was rather covetous about it, and highly sensitive to criticism. 

Newton begins his 1672 account by relating his surprise that the colored spectrum produced by his prism was rectangular in shape rather than circular, "as the received laws of Refraction" would lead one to expect. It seems a rather trifling question, especially to lead to such profound conclusions. In fact, his "surprise" is hard to credit, for this effect of a prism was well known, not least to Newton himself, who had been fascinated with such instruments since he was a boy. 

Newton was here no doubt indulging what is now a common practice in scientific papers: to construct a retrospective story so as to give a comprehensible narrative arc to a description of experiments that might have a more haphazard genesis and perhaps initially a different goal entirely. At any rate, Newton embarked on a thorough program of experimentation to figure out what the prism was doing to light. 

One can imagine him almost literally playing with prisms, screens, and lenses until he found a configuration that allowed him to formulate and investigate some definite hypotheses. (Newton once famously claimed that "I feign no hypotheses," but in truth one can hardly do science at all without them.) 

It's a common situation for experimental science: you might want to investigate a phenomenon but be unsure quite what the right questions are, let alone how to deploy your instruments and measuring devices to answer them. You need to develop a feeling for the system you're trying to study. 

Newton closed the "window-shuts" of his room, admitting a single narrow beam of sunlight through a hole, which passed into the prism. In the crucial experiment, Newton investigated the nature of the light after it exited the prism. If the light became colored because of some transformation produced by the prism, then a passage through a second prism might be expected to alter the light again. 

Newton used a board with a hole in it to screen off all the spectrum except for a single color — red, say — and then allowed that colored light to pass through the second prism. He found that this light emerged from the second prism refracted — bent at an angle — but otherwise unchanged. In other words, a prism seems only to bend (refract) light, leaving it otherwise unaltered. But it does so to different degrees (that is, at different angles) for different colors. 

This in itself was nothing new: the Anglo-Irish scientist Robert Boyle had said as much in his 1664 book "Experiments and Considerations Touching Colours," which Newton had read. But only Newton saw what this implies: that refraction is then all there is to it. 

The colors themselves are already in the white light, and all the prism does is to separate them out. As he put it, "Light consists of Rays differently refrangible" [meaning refractable]. The colors of the spectrum, then, "are not Qualifications [alterations] of Light … (as 'tis generally believed), but Original and connate properties." That was a bold interpretation: sunlight was not, so to speak, elemental, but compound. 

To test this idea, Newton used a lens to refocus a many-hued spectrum into a single, merged beam — which, he observed, was white. He also passed this reconstituted beam through another prism to reveal that it could again be split into a spectrum just as before. 

Newton explained how his observations could account for the rainbow, produced by the refraction and reflection of light through raindrops that act as tiny prisms. The colors of everyday objects, he added, arise because they reflect "one sort of light in greater plenty than another." 

And the results explained the defects of lenses (Newton himself had become adept at making these by grinding glass), whereby refraction of different colors produces a defocusing effect called chromatic aberration. The Royal Society's secretary Henry Oldenburg told Newton that his report was met with "uncommon applause" when read at a gathering in February 1672. But not everyone appreciated it. 

After the paper was published in the society's Philosophical Transactions, its in-house curator of experiments, Robert Hooke, who considered himself an expert on optics, presented several criticisms (which we can now see were mistaken). Newton replied with lofty condescension, igniting a long-standing feud between the two men. 

One problem is that Newton's experiments, despite their apparent simplicity, are not easy to replicate: some, in England and abroad, tried and failed. But they have stood the test of time, a testament to the power of experiment to literally illuminate the unknown that, in the judgment of philosopher of science Robert Crease, gives Newton's so-called experimentum crucis "a kind of moral beauty."

Reprinted with permission from Beautiful Experiments: An Illustrated History of Experimental Science by Philip Ball, published by The University of Chicago Press. © 2023 by Quarto Publishing plc. All rights reserved.

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.

An outbreak of Salmonella infections linked to small turtles has sickened 26 people across 11 states.

The sale of turtles with shells shorter than 4 inches (10.16 centimeters) has been banned in the U.S. since 1975, according to the Centers for Disease Control and Prevention (CDC). That's because tiny turtles are the most common culprits in Salmonella outbreaks linked to pet reptiles. The pets pose a particular risk to children, who are likely to handle the turtles and get sick.

Nonetheless, tiny turtles are still sold illegally online and at stores, flea markets and roadside stands. 

Now, the CDC is investigating an outbreak of Salmonella caused by two strains of the disease-causing bacteria and likely linked to small pet turtles, the agency announced Friday (Aug. 18). People affected by the outbreak got sick between Oct. 27, 2022, and July 16, 2023. The true number of people affected is likely higher than reported, the CDC noted. 

Related: Salmonella outbreak in 4 states linked to ground beef, CDC warns 

Of 20 people interviewed by state and local health officials, 16 reported contact with pet turtles in the week before they got sick. Most also reported the pet's size and said they'd had contact with a turtle whose shell was less than 4 inches long. 

In addition, Salmonella samples from the sick individuals were very closely related, genetically. This suggests they all got sick after handling the same type of animal, the CDC noted.

Of 13 people asked, six reported buying their pet turtle online, five said they bought the animal at a store and one reported buying their turtle at a reptile show. "Investigators are working to determine if there is a common source of turtles," the CDC announcement states.

Even healthy-looking turtles can carry Salmonella. The animals pass the germs in their stool, which can then contaminate the turtles' bodies, tank water and objects in their environment. Humans can get infected after touching infected animals, their feces or their environments and then touching their own mouths or food. 

"Don't kiss or snuggle your turtle, and don't eat or drink around it," the CDC advisory states.

Salmonella infection, or salmonellosis, can cause symptoms of fever, stomach cramps and bloody diarrhea. In rare cases, the infection can spread from the gut to the bloodstream and other parts of the body, like the joints or the fluid around the spinal cord and brain.

Symptoms of salmonellosis usually appear six hours to six days after exposure to the bacteria and last four to seven days, but sometimes they don't emerge for several weeks and last longer. Most people recover without treatment, but those with severe cases are given antibiotics to kill the bacteria. People may also require fluids to counter dehydration caused by diarrhea. 

The CDC's investigation page offers tips for how to safely purchase and handle pet turtles, and the agency also advises people to call a health care provider right away if they have severe symptoms of Salmonella. 

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.

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.

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."

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.

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.

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.

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 ocean is filled with creatures that might look strange to human eyes. But every once in a while, these weirdos from the deep make an appearance on dry ground. Here are 10 instances when these ocean animals came (or were spied from) ashore in 2020. 

Giant squid with foot-wide eyes

It's rare to see a giant squid (Architeuthis dux), so people took notice when one washed ashore in Cape Town, South Africa on June 7. These squid are very eccentric-looking — their eight arms and two tentacles are covered with serrated suckers with powerful suction; they have the largest eyes in the animal kingdom (measuring 1 foot, or 30 centimeters, in diameter); and they can reach lengths up to 60 feet (18 meters).

This particular giant squid is now in the collections of the Iziko Museums of South Africa, and its DNA may help researchers determine if there is just one or many species of giant squid living deep beneath the waves.

Read more: Stunningly intact giant squid washes ashore in South Africa

7-armed octopus (where's the 8th arm?)

When a man spotted a "red glob" on the rocky beach of an island near Seattle, he snapped some photos that set off a friendly debate about the creature's identity. The blob was clearly a cephalopod (a group that includes squid, octopus, cuttlefish and nautilus), but what species was it?

The scientific consensus arrived at the seven-armed octopus (Haliphron atlanticus), a deepwater creature that usually doesn't swim in Washington's cold coastal waters.

Despite its curious name, the octopus has more than seven arms. In males, the eighth arm is used during mating, and the rest of the time it stays modestly tucked away in a sac near its right eye. 

Read more: Bright 'red glob' washes ashore in Washington. It may be a 7-armed octopus.

9-armed octopus almost becomes dinner

After a seaweed farmer caught some octopuses in a trap off Japan, he took them home for his mother to cook. But just after she dropped one in a boiling pot, she realized that it had nine arms, so she fished it out.

How did this octopus get nine arms? Just like lizards can regrow tails, octopuses can regrow arms. However, sometimes the regeneration process flubs and the regrown arm gets an offshoot, or ninth arm. Sometimes these flubs can happen over and over again — one octopus reportedly ended up with 90 arms, according to a 1965 study.

The family donated the nine-armed octopus's body to a local museum so the public can see this unusual curiosity. 

Read more: Rare 9-armed octopus found off Japan coast

Mass die-off

Thousands of dead sea creatures, including octopuses, fish and starfish, washed ashore on the remote Russian peninsula of Kamchatka. The culprit? A mass poisoning event. Even surfers were bothered by it, saying they felt a mild burning in their eyes after going into the bay. 

The die-off may have wiped out as many as 95% of the animals in Kamchatka's Avacha Bay, a catastrophic event that will likely disrupt the food chain in that area for the remaining animals, local researchers said. 

Local and international scientists initially thought that human-made pollution caused the die-off when it started in early October. However, since then it's come to light that toxic algae could have been the cause of this ecological disaster, the BBC reported.

Read more: Dead animals are washing ashore on a remote Russian peninsula. What's going on?

Gone fishing

A man was dismayed to discover that his pet goldfish, Cleo, had met her end from an unexpected eight-legged predator: a spider. 

Cleo lived in a pond by the man's house. Apparently, so did her assassin — a nursery web spider, or a semiaquatic arachnid that can walk on still water, dive under the surface to escape predators and even "fish" for prey many times its size.

This nursery web spider dragged Cleo ashore, apparently for a fishy feast. (We're sorry, Cleo!)  

Read more: A man caught a spider eating his pet goldfish and, well, it's terrifying

Trashy poop

A green turtle caught in a net off the coast of Argentina had a very upset tummy. How do we know? It pooped out loads of human trash, including pieces of nylon bags and hard plastics. 

It's likely the turtle mistook this trash for its regular prey, such as jellyfish, seagrasses and worms. The trash it ate instead took up room in its belly, which probably made it hard for the turtle to eat real food and get the nutrients it needed to survive.

Veterinarians gave the turtle a medication that helped it poop, and the turtle recovered, according to the Mundo Marino Foundation in Argentina. 

Read more: Green turtle rescued from fishing net poops out all kinds of human trash

Shark versus swordfish

Scientists were thrown for a loop when a dead thresher shark washed ashore on the coast of Libya with a swordfish's "sword" embedded in its body. Swordfish are known to be aggressive toward animals they perceive as threats (including some whales, sea turtles and humans), but they've never been documented attacking thresher sharks before. 

Thresher sharks eat small fish and wouldn't be a threat to swordfish, the researchers said.

Perhaps, the two were fighting over prey, the scientists said, although it's also possible the stabbing was an accident.

Read more: Whodunit solved when 'sword' is found embedded in thresher shark

Fishy love

What do you get when you unintentionally cross Russian sturgeon with American paddlefish?

An unusual love hybrid — everybody, say "hello" to the sturddlefish.

There are about 100 of this odd hybrid in captivity now, researchers announced in the journal Genes. Scientists have no plans to make more. The sturddlefish came into being when the team attempted to help the critically endangered Russian sturgeon (Acipenser gueldenstaedtii), a popular caviar supplier, reproduce. The researchers thought that American paddlefish sperm would trigger asexual egg development in the sturgeon, but (as you probably guessed), that's not what happened. The sturgeon's eggs fused with the paddlefish sperm, and hybrids were born. 

Mazel tov! 

Read more: Scientists accidentally create 'impossible' hybrid fish

Puppy-size sea "pill bugs"

Remember looking for pill bugs (or potato bugs or roly polies) when you were a kid? Can you imagine a big one, about the size of a puppy, lurking deep in the sea?

Like a pill bug, this freaky-looking beast is an isopod, and it's the largest one on record. Found in Indonesia and dubbed Bathynomus raksasa ("rakasa" translates to "giant" in Indonesian), this isopod measures about 13 inches (33 cm) long and is the first new giant isopod to be found in more than a decade. 

Read more: Massive 'Darth Vader' sea bug pulled from waters near Indonesia

Marine blob 

What looks like a party balloon but lives deep underwater? A new species of ctenophore called Duobrachium sparksae that's related to comb jellies.

Researchers first spied these weird, golf tee-size beings in an underwater canyon off the coast of Puerto Rico in 2015, but they didn't publish the results until this year. Every time D. sparksae (can we just call it "sparky"?) moves, rows of its tiny hair-like cilia refract light into a prism of shining colors, Live Science reported. 

We hope Sparky has a great New Year, and that you do too! 

Read more: Newfound marine blob looks like 'party balloon' with two strings, scientists say

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.

• In photos: Tagging baby sea turtles
• Amazing journey: World-traveling sea turtle goes home
• Image gallery: 25 amazing ancient beasts

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.

• In Photos: Tagging Baby Sea Turtles
• Photos: See the World's Cutest Sea Creatures
• Image Gallery: Pile of Turtle Fossils Unearthed

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.

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 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.

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.

Follow Joseph Castro on Twitter. Follow us @livescience, Facebook & Google+.

When scientists collect or observe animals in the wild, it sometimes can be extremely challenging to identify their sex. But a group of researchers recently found an innovative and relatively simple way to determine the sex of turtles in the field, coaxing reluctant males into, um, revealing themselves, through the judicious application of a vibrator.

They put four turtle species to a new and titillating test, applying their turtle tickler — a 7-inch-long (18 centimeters), handheld vibrator — to the nether regions of western chicken turtles (Deirochelys reticularia miaria), Mississippi mud turtles (Kinosternon subrubrum hippocrepis), common musk turtles (Sternotherus odoratus) and spiny softshell turtles (Apalone spinifera).

And while there were varying degrees of success between the species, the researchers reported in a new study that plenty of the turtle males obligingly rose to the occasion. [The 9 Weirdest Animal Penises]

In some turtle species, it can be difficult to tell the sexes apart just by looking at them. Either the males and females aren't very different in size or body shape, or the individual turtles exhibit secondary sex traits that belong to both males and females, the study authors reported.

And traditional methods for distinguishing turtle sexes — such as sampling blood for sex hormone analysis, minor surgery, or camera insertion into their genital areas — are time-consuming and invasive, and tricky to perform outside of a laboratory's controlled environment, study lead author Donald McKnight, a doctoral candidate with the College of Marine and Environmental Sciences at James Cook University in Australia, told Live Science in an email.

"Although this is an admittedly comical method, it does actually have scientific merit because it is less invasive for the animals and easier and cheaper for the researchers," McKnight said.

Lending a hand

This isn't the first time that scientists have experimented with stimulating male turtles to tell the sexes apart. Earlier efforts found that Cotinga River toadhead turtles (Phrynops tuberosus) would become erect if their limbs and neck were immobilized, while common snapping turtles (Chelydra serpentina) would show their penises if they were gently bounced up and down, the study authors wrote.

And a prior study used vibrators on male turtles to make them ejaculate, which suggested that vibrators could shake things up for field researchers trying to induce turtle erections.

Using the vibrator, the scientists correctly identified the sex of 100 percent of their A. spinifera turtles and 80 percent of K. subrubrum hippocrepis, according to the study. The other two species were somewhat less responsive, enabling the scientists to identify the sex of about 65 percent of their D. reticularia miaria turtles and 56 percent of S. odoratus.

All four turtle species in the study seemed to prefer the vibrator at its highest setting and with fresh batteries, according to McKnight. However, distinct preferences among the species also emerged.

Spiny softshell turtles appeared to enjoy having their tails stimulated, frequently wagging them "from side to side," the study authors reported. Meanwhile, Mississippi mud turtles and musk turtles were most responsive to "slow, small circles" on their abdominal and pectoral regions. Western chicken turtles also enjoyed the circular movements, but higher up on their pectorals, according to the researchers.

Previous research suggested that male turtles could be coaxed into ejaculating with the application of a vibrator to their heads. The study authors dutifully tested that technique, but found that it generally left their turtles unimpressed, adding to their conclusion that not all vibration methods work equally well across species.

"The best future directions would be to try several different styles of vibrator to see if some are more effective than others, as well as to test this method on a wider range of species — especially species that are known to be difficult to sex," McKnight told Live Science.

In other words: Different folks need different strokes. Even when those folks are turtles.

The findings were published online in the June 2017 issue of the journal Acta Herpetologica.

Original article on Live Science.

Cambodia's national reptile is on the brink of extinction, but there may be new hope for the reptiles after nine Cambodian Royal Turtle babies were successfully hatched, conservationists recently announced.

The Royal Turtle, also known as the southern river terrapin (Batagur affinis), is one of the world's most endangered freshwater turtles, conservationists said. The turtle is listed as critically endangered by theInternational Union for Conservation of Nature (IUCN) and was thought to be extinct in Cambodia. After a small population was discovered in the Sre Ambel River in 2000, a protection program was launched and community members were encouraged to find and protect turtle nests.

A villager found a nest containing 14 eggs in February, and with assistance from the Royal Turtle Conservation Team from the Fisheries Administration (FiA) and the Wildlife Conservation Society (WCS), the nest was fenced in and protected for three months until the turtles hatched. [Photos: Thousands of Baby Turtles Hatch in Brazil]

"I am delighted to see those eggs have successfully hatched, and that the hatchlings have been taken to the conservation center in Koh Kong Province," Long Sman, who guarded the Royal Turtle nest for three months, said in a statement. "I am proud of the result, and especially to be part of conserving Cambodia's Royal Turtles from extinction."

The nine turtles that successfully hatched were relocated to the Koh Kong Reptile Conservation Center. The hatchlings will be raised at the center and may be part of a breeding program in the future, according to the WCS.

Very few Royal Turtles are left in the wild, and only one nest was found this year, according to Som Sitha, WCS's technical advisor for the conservation project. Two nests were found in 2016, and three nests were found in 2015, the WCS said.

"This is a big concern for Royal Turtle conservation," Sitha added. "If sand dredging, illegal clearance of flooded forests and illegal fishing continues, then our national reptile species faces a high risk of extinction."

Original article on Live Science.

If scientists were to draw an enormous family tree for all of Earth's animals, the oldest branch would belong to the jellyfish, a new study finds.

The result is the latest in a decade-long debate over which came first: the jellyfish or the sponge. The sponge has long been a crowd favorite because its body is extremely simple when compared with other animals. But a new, detailed genetic analysis revealed that the delicate predator the comb jelly (a ctenophore) evolved first, the researchers in the new study said.

The results will help scientists determine how the nervous system, digestive tract and other basic organs evolved in animals, the researchers said. [7 Theories on the Origin of Life]

The debate began in 2008, when a family-tree study pointed not to sponges — long identified as the "earliest animal" — but to comb jellies as the earliest members of the animal kingdom. In the following years, scientists published papers with conflicting results. The latest study, which came out online in March in the journal Current Biology, showed an impressive genetic dataset supporting the sponges' position at the base of the family tree, the researchers said.

But while these "big data" approaches work in 95 percent of all family-tree cases, "it has led to apparently irreconcilable differences in the remaining 5 percent," study senior researcher Antonis Rokas, a professor of biological sciences at Vanderbilt University in Nashville, Tennessee, said in a statement.

To investigate, Rokas and his colleagues looked at 18 controversial relationships — seven from animals, five from plants and six from fungi — to learn why these parts of the family tree provoked so many conflicting results. The researchers did this via a lengthy comparison of individual genes from each contender (such as the jellies and sponges) to many of the contenders' relatives on the family tree, the scientists said.

"In these analyses, we only use genes that are shared across all organisms," Rokas said. "The trick is to examine the gene sequences from different organisms to figure out who they [the sequences] identify as their closest relatives. When you look at a particular gene in an organism — let's call it A — we ask if it is most closely related to its counterpart in organism B, or to its counterpart in organism C, and by how much."

The researchers studied thousands of genes to find how many genes from each animal — in this case, the sponge and the comb jelly — had the most support for being the first animal in the family tree. The one with more genes in common with its close relatives had higher phylogenetic signals. (Phylogeny is the scientific term for family tree.)

The earlier an animal emerged on Earth, the earlier it likely diverged into new species, the researchers said. As such, that organism would have more related species and so a higher phylogenetic signal. The new study's results revealed that the comb jelly had more genes that support the "first-to-diverge" status than the sponges did.

The team also examined whether crocodiles were more closely related to birds or turtles. Among these animals, 74 percent of the shared genes favored the idea that crocodiles and turtles were sister lineages, while birds were close cousins. [Dangers in the Deep: 10 Scariest Sea Creatures]

The holdup

Just one or two "strongly opinionated genes," or those that have strong phylogenetic signal for one of the specific hypotheses tested over the other (for instance, such a gene might strongly favor "sponges-first" over "jellies-first"), likely led to the contentious results in other studies, the researchers in the new study said. Statistical methods used in earlier studies were highly susceptible to the influence of these genes, the researchers said.

The removal of even one opinionated gene can flip the results' conclusion about which candidate appeared first, the researchers said. They found that when this happens, the mystery may never be solved, either because the data are inadequate or because the diversification happened too fast for researchers to determine which candidate arose first.

Even so, the new analysis does solve some of the less contentious issues, the researchers said.

"We believe that our approach can help resolve many of these long-standing controversies and raise the game of phylogenetic reconstruction to a new level," Rokas said.

The study was published online today (April 10) in the journal Nature Ecology & Evolution.

Original article on Live Science.

Swallowed fishhooks are a deadly threat to freshwater turtles, and until now, this danger was largely unexplored. A new study, however, finds that in some species, the likelihood of a turtle dying from a swallowed fishhook is as high as 11 percent, and that the frequency of turtle deaths from fishhooks would be enough to nudge vulnerable turtle populations into decline.

Threats to sea turtles from commercial fishing — such as swallowing hooks — are well-documented, but far less is known about how recreational fishing and the threat of swallowed fishhooks impacts freshwater turtles.

Recently, researchers evaluated data from multiple studies to calculate the probability of freshwater turtles ingesting fishhooks, how often that would prove to be fatal, and how deaths from swallowed hooks could affect turtle population numbers. [Fishhooks Threaten Freshwater Turtles | Video]

Prior research suggested that hook ingestion in freshwater turtles is more widespread than scientists had suspected. In 2014, scientists gathered X-rays of more than 600 turtles representing four species, and found fishhooks in 33 percent of the animals. Another survey detected evidence of hooks in 36 percent of alligator snapping turtles in one Florida river, the authors reported in the new study.

"If you ask anyone who's gone fishing with live bait, there's a chance they've hooked a turtle," study co-author David Steen, an assistant research professor in the Department of Biological Sciences at Auburn University Museum, told Live Science.

"But there hasn't been an opportunity to look at this on a grand scale and see what's been going on," Steen said.

In sea turtles, interactions with commercial fishing gear, including hooks, is known to be frequently deadly, with mortality rates of up to 82 percent, the authors wrote in the new study. But relatively little has been done to better understand how freshwater turtles are affected when they swallow fishhooks.

"So we took the data from sea turtles and applied it to freshwater turtle populations," Steen said.

Calculating the risk

Steen and study co-author Orin J. Robinson Jr., a postdoctoral researcher with the Cornell Lab of Ornithology at Cornell University, modeled estimates for freshwater turtle mortality based on sea turtle mortality rates. Then, they combined those estimates with long-term data on turtle life histories in known populations, to see if they would be significantly affected by the deaths.

Turtles in the wild produce a lot of young, but many of their babies die before reaching adulthood, so high survival rates among adults — which can live for many decades — help to keep populations stable, Steen said.

However, if the mortality rates among adults go up, it can lead to a population decline. And the computer models showed that deaths from fishhooks would be significant enough to cause turtle populations to drop, the researchers said.

Freshwater turtles are known to face threats from human activity, such as habitat loss and overharvesting for food and pet trades, and the new findings suggest that fishhook ingestion should be added to that list, Steen told Live Science.

"Sea turtles have been a subject of study for many years, and people have come up with strategies to protect them from bycatch," Steen said. "Policymakers and land managers might consider whether they should be regulating or monitoring the type of fishing that's going on in areas with vulnerable freshwater turtles."

The findings were published online March 15 in the journal Conservation Biology.

Original article on Live Science.

Shortly after an asteroid smashed into Earth about 65.5 million years ago, obliterating much of life on Earth,an ancient sea turtle with a triangular-shaped head swam along the relatively arid shores of southern Africa, a new study finds.

The creature, a newly identified species, lived about 64 million years ago during the Paleocene, an epoch within the Paleogene period, the researchers said. The animal is closely related to earlier sea turtles that lived before the asteroid struck, an event known as the Cretaceous–Paleogene (K-Pg) boundary, which marks the mass extinction that killed about 75 percent of all species on Earth, including the nonavian dinosaurs.

"If these sea turtles do, in fact, form a tightly knit group, evolutionarily speaking, then the [African] specimen provides proof that members of that group survived the mass extinction at the end of the Cretaceous," study lead researcher Timothy Myers, a research assistant professor in the Department of Earth Sciences at Southern Methodist University in Texas, told Live Science in an email. [See Photos of the Ancient Sea Turtle from Angola]

Paleontologists found the specimen along the sea cliffs near the town of Landana, in the Angolan province of Cabinda in June 2012. Study senior researcher Louis Jacobs, a vertebrate paleontologist at Southern Methodist University, noticed part of the bone protruding from the rock. He and his team soon realized it was a nearly complete turtle skull and most of a hyoid, a U-shaped neck bone that supports the tongue.

The Cabinda turtle, which researchers have yet to formally name, was about the size of a small round table, measuring about 3.2 feet (1 meter) long. Its eyes faced forward and slightly to the side, Myers said.

An analysis of the skull showed that the early turtle had an expanded palatal surface (the palate is the roof of the mouth). This suggests that an early adaptation allowed the animal to eat hard foods that needed to be crushed prior to ingestion.  

"Based on the palatal [shape], I assume that adult turtles would have eaten hard-shelled organisms like crustaceans (crabs, lobsters), bivalves and gastropods in addition to softer prey like squid or fish," Myers said.

Further analysis indicated that the Cabinda turtle was an early member of a group of modern sea turtles that includes hawksbill and green sea turtles, he added. But the newfound specimen likely belongs to a different taxon, or group, of the Chelonioid (sea turtle) family, the researchers said.

The turtle isn't the only specimen unearthed in Cabinda. The site has also yielded fossils of snakes, crocodiles, bony fishes and sharks, Myers said. The side-necked turtle species Taphrosphys congolensis was also discovered there, the researchers said.

The fossil site was once a parched habitat, Myers said.

"In the early Paleocene, the site was a sandy, shallow marine environment, not far from the coast," Myers said. "This part of Africa was at a higher latitude 64 million years ago, so the climate would have been relatively arid, and the onshore environments adjacent to the locality would not have had the thick jungle vegetation they do today."

The study, which has yet to be published in a peer-reviewed journal, was presented Oct. 28 at the 2016 Society of Vertebrate Paleontology meeting.

Original article on Live Science.

Ancient links

About 64 million years ago, a sea turtle with a triangular-shaped head swam along the arid coastline of what is now Angola. The creature likely crunched on hard-shelled animals, such as crabs and lobsters, with its extra-long palate — the roof of its mouth.

The finding is remarkable, but even more breathtaking is its link to early sea turtles that lived before the asteroid hit Earth about 65.5 million years ago, the researchers of the new study said. That link indicates that this particular turtle group survived the mass extinction that killed the nonavian dinosaurs, the researchers said.

The study, which has yet to be published in a peer-reviewed journal, was presented Friday (Oct. 28) at the 2016 Society of Vertebrate Paleontology meeting. [Read the Full Story on the Ancient Sea Turtle from Angola]

Skull unearthed

Researchers discovered the almost-complete turtle skull in the Angolan province of Cabinda in June 2012. They also found a hyoid, a U-shaped neck bone that supports the tongue.

Here, Ricardo Araújo, a former doctoral student at Southern Methodist University in Texas, helps to excavate the skull in Angola.

Turtle skull

A view of the front of the ancient sea turtle's skull. Notice its two eye orbits and its naris, or nose.

Bird's-eye view

The top of the ancient sea turtle's skull. The turtle's body was likely the size of a small round table, about 3.2 feet (1 meter) long, said study first author Timothy Myers, a research assistant professor in the Department of Earth Sciences at Southern Methodist University.

Find your beach

The beach at the town of Landana, located in the Angolan province of Cabinda. The turtle skull was found in the cliffs in the background. The site has housed other fossil specimens, including those of snakes, crocodiles, other turtles, bony fishes and sharks, Myers said.

Rocky cliffs

The outcrop where study senior author Louis Jacobs, a vertebrate paleontologist at Southern Methodist University, discovered the sea turtle skull.

Mucky finding

The skull was still covered with muck after researchers removed the rock surrounding the fossil. When the turtle was alive, about 64 million years ago, "the site was a sandy, shallow marine environment, not far from the coast," Myers said.

[Read the Full Story on the Ancient Sea Turtle from Angola]

Dinosaurs likely had a gene that gave them a double win — red coloring and the ability to see the color red, a new study finds.

This so-called "red gene" gives living dinosaur relatives, including birds and turtles, red coloring on their bodies and the ability to see more colors within the red spectrum than people can see, the researchers said.

"Humans can distinguish between some shades of red such as scarlet and crimson. However, birds and turtles can see a host of intermediate reds between these two shades," study senior author Nick Mundy, an evolutionary geneticist at the University of Cambridge, said in a statement. "Our work suggests that dinosaurs would have also had this ability to see a wide spectrum of redness."

Seeing red

The gene, called CYP2J19, allows birds and turtles to convert yellow pigments they eat into red hues on their bodies, shells or beaks. These red pigments can also be used to strengthen their ability to see red  through droplets of red oil in their retinas (the light-sensitive tissue at the back of the eye), the researchers said. [Paleo-Art: Dinosaurs Come to Life in Stunning Illustrations]

Unlike mammals, birds and turtles have retinal cones that contain brightly colored oil droplets, such as green, yellow and red, that help them see those colors, the researchers said. The oil droplets are akin to a color filter on a camera lens. "By filtering the incoming light, the oil droplets lead to greater separation of the range of wavelengths that each cone responds to, creating much better color sensitivity," Mundy said in the statement.

To learn about the evolutionary history of the CYP2J19 gene, the researchers reconstructed a family tree that dated back millions of years, and found that the "red gene" originated about 250 million years ago.

That's before turtles broke off from the archosaur line, a group that includes crocodiles, dinosaurs and birds, the researchers said. Given that the gene is older than dinosaurs themselves (the first dinosaurs appeared between 245 million and 240 million years ago), it's likely that dinosaurs also carried this "red gene" and the enhanced red vision that it enabled, the researchers said. 

It's also possible that the gene gave some dinosaurs red coloring, but this is more speculative, the researchers said.

Healthy red signal

Seeing red may have helped dinosaurs pick the best mates, the researchers speculated.

Research on zebra finches, which also hold this red gene, suggests that redder birds are healthier. That's because there may be a link between red beaks and the bird's ability to break down toxins in the body, the researchers said. There is similar evidence among red-eared terrapins (freshwater turtles) suggesting that terrapins with redder ears are healthier than their less-rosy counterparts.

"The excellent red spectrum vision provided by the CYP2J19 gene would help female birds and turtles pick the brightest red males," the study's lead author, Hanlu Twyman, a doctoral student in the Department of Zoology at the University of Cambridge in England, said in the statement. [Wipe Out: History's Most Mysterious Extinctions]

A lucky few

Despite the gene's old age (evolutionarily speaking), only a few types of animals have it. The ancestral lineage that gave rise to the scaly lizards and snakes broke off before the red gene arose. That explains why these reptiles either don't have retinal oil droplets, or have only yellow and green droplets, the researchers said.

Crocodiles split from the common "red" ancestor after turtles did, but they seem to have lost the CYP2J19 gene. Moreover, the CYP2J19 gene arose after the divergence of reptiles and mammals, which explains why humans don't have oil droplets in their eyes today, the researchers wrote in the study, published online today (Aug. 3) in the journal Proceedings of the Royal Society B.

Original article on Live Science.

The turtle's shell may serve as a protective shield nowadays, but ancient turtles actually developed shells for an entirely different reason, a new study finds.

Researchers looked at the remains of 47 ancient proto-turtles (Eunotosaurus africanus), ancient reptiles that sported partial shells. These animals had broadened ribs that likely helped them burrow underground, rather than serving as protective armor, the researchers said.

"Why the turtle shell evolved is a very Dr. Seuss-like question, and the answer seems pretty obvious — it was for protection," lead study author Tyler Lyson, a curator of vertebrate paleontology at the Denver Museum of Nature & Science, said in a statement. However, for the earliest turtles, "the turtle shell was not for protection, but rather for digging underground to escape the harsh South African environment where these early proto-turtles lived." [Image Gallery: 25 Amazing Ancient Beasts]

The evolutionary history of the turtle shell has long mystified scientists, largely because of "the scarcity of critical fossils," the researchers wrote in the study.

"We knew from both the fossil record and observing how the turtle shell develops in modern turtles that one of the first major changes toward a shell was the broadening of the ribs," Lyson said.

However, broadened ribs aren't exactly helpful for protection. In fact, they slow down their owner and make it difficult for the animal to move and breathe, the researchers said. For instance, ribs are used to support the body during movement and provide room for the lungs to expand. But broadened ribs stiffen the torso — which makes breathing challenging and the animal's strides shorter and slower.

Moreover, the ribs in most animals look the same, likely because they serve the same role across species.

"Ribs are generally pretty boring bones," Lyson said. "The ribs of whales, snakes, dinosaurs, humans and pretty much all other animals look the same. Turtles are the one exception, where they are highly modified to form the majority of the shell."

A boy's discovery

An analysis of the fossils in the new study, including a key 260-million-year-old fossil found by an 8-year-old boy in South Africa, helped researchers zero in on the turtle shell's beginnings.

The boy, Kobus Snyman, discovered the 6-inch-long (15 centimeters) proto-turtle fossil on his father's farm on the Western Cape of South Africa. The stunning specimen includes most of the skeleton, as well as the ancient reptile's hands and feet.

"I want to thank Kobus Snyman and shake his hand because, without Kobus, both finding the specimen and taking it to his local museum, the Fransie Pienaar Museum in Prince Albert, this study would not have been possible," said study co-author Bruce Rubidge, a professor at the Evolutionary Studies Institute at the University of Witwatersrand, in Johannesburg.

It's likely that the proto-turtle's ability to burrow underground helped it survive the Permian-Triassic extinction about 252 million years ago, the researchers said. They added that it took about 50 million years for the proto-turtles' broadened ribs to develop into a fully formed shell.

The study was published online Thursday (July 14) in the journal Current Biology. 

Original article on Live Science.

There may be such a thing as too many turtles, according to scientists investigating why so few turtle eggs were hatching on Raine Island, located on the tip of Australiaꞌs Great Barrier Reef.

For more than 1,000 years, green sea turtles have nested on Raine Island, where they dig pits to lay and bury their developing eggs. Yet after a millennia of fruitful nesting seasons, the island has recently had a drop in the rate of successful hatches — now less than 30 percent, even in undisturbed nests.

With protective coral along the broad sandy beaches, and no land-based predators, scientists were stumped as to why an otherwise ideal nesting location would have so few baby turtles hatching from eggs and scuttling down to the water. [Photos: Thousands of Baby Turtles Hatch in Brazil]

Seawater was the first suspect. Scientists thought flooding of the nests during high tides was killing newly laid eggs, which cannot survive underwater. Sand was added to a section of the beach in 2014, raising it by 3 to 5 feet (1 to 1.5 meters), but hatching rates were still extremely low. Then in 2015, hatching success doubled, leaving scientists to question what had changed.

A new theory from researcher David Booth of the University of Queensland suggests that the island's popularity for nesting is to blame for the plunge in hatching success.

Fewer turtles laid nests on the island in 2015, Booth said in a statement. That bit of information suggested that "a density-depending effect was limiting hatching rates even in nests that remained undisturbed throughout incubation, rather than the environmental conditions."

The Queensland Department of Environment and Heritage Protection estimates as many as 60,000 female green turtles swim from their feeding grounds in Indonesia, Papua New Guinea, the Torres Strait and the West Pacific to the tiny Raine Island to lay their eggs.

The number of turtles to visit the island each nesting season is highly variable, Booth told Live Science, "with as few as 5,000 in a very low nesting year." An estimated 15,000 females visited the island in the 2014-2015 nesting year, while only 5,000 did so in 2015-2016.

With a high number of nests, nutrients and oxygen beneath the sand could be used more quickly. Nest density could also increase the levels of bacteria in the nests, the researchers said.

"Because the nests generally remain undisturbed by other nesting turtles, the most likely explanation is low oxygen or high carbon-dioxide levels, or an increase in disease-causing microorganisms," Booth said.

To test his theory, Booth will investigate whether pumping air into the nests will boost the hatching rate. If correct, nesting density could explain a similar phenomenon of low hatching rates in other turtle populations, such as Olive Ridley turtles, he said.

The hypothesis is scheduled to be presented at the annual meeting for the Society for Experimental Biology today (July 7) in Brighton, England, and has yet to be published in a scientific journal.

Original article on Live Science.

Editor's Note: This article was updated to include information on why turtle nesting varies from year to year.

In an ancient settlement on the banks of the Tigris River in Turkey, archaeologists have made a strange discovery: 17 butchered soft-shelled turtles in the grave of a woman and child.

These river turtles were not a typical Mesopotamian menu offering 2,500 years ago, but the researchers think that, in this case, the animals may have been eaten in a funeral ritual before being buried with the dead.

The grave was discovered at an ancient mound site called Kavuşan Höyük, near the modern town of Bismil in southeastern Turkey. The archaeological record suggests the site was occupied for a very long time —from the late third millennium B.C. to the 14th century A.D.—but now, it's about to disappear. Once the controversial Ilisu Dam project is finished, Kavuşan Höyük and several other historic sites like Hasankeyf will be flooded with a new reservoir. [8 Grisly Archaeological Discoveries]

Ahead of this hydroelectric project, salvage excavations took place along the banks of the Tigris to save and study the archaeological materials that are soon to be underwater. At Kavuşan Höyük, digging took place from 2001 to 2009.

In the 2008 season, archaeologists discovered three ancient silos that had been dug into a mud floor dating back to the post-Assyrian period, around the sixth century B.C. These silos would have originally been used for grain or cereal storage, but one of them was repurposed for a grave. At the bottom of it, excavators found a woman and a child, buried directly on top of each other. Surrounding them were the carapaces (shells) and other skeletal remains of 17 Euphrates soft-shelled turtles (Rafetus euphraticus).

"It was really something unexpected," said Rémi Berthon, a zooarchaeologist at the National Museum of Natural History in Paris, who was tasked with studying the animal remains. Turtle shells —and, more commonly, tortoise shells —have been found in graves in the Near East before. But finding Euphrates soft-shelled turtles, and so many of them, was a surprise.

What's more, Berthon saw clear evidence that the turtles had been butchered. The cut marks on the bones suggest the turtles were placed on their backs and were cut open for the meat inside; their limbs were cut off as well, the researchers said.

Berthon said he hasn't tasted soft-shelled turtle meat himself, and he'd probably be in trouble with conservationists if he did: The Euphrates soft-shelled turtle is listed as endangered by the International Union for Conservation of Nature (IUCN). Despite its precarious status, the species was not held in much regard locally. Though ethnographic sources suggest the turtles are sometimes sold at fish markets, the animals have no economic function in the region today.

"I think that fishermen are not really happy with this species because they think they are too aggressive and destroy the fishing nets," Berthon said.

There is evidence from other archaeological sites that turtles and tortoises may have been seen as guides to the afterlife in some cultures. For example, the shells and skulls of green sea turtles were often found on graves at the Ra's al Hamra 5 cemetery, in Oman, which dates back to the fourth millennium B.C.

"We knew already that, in the Near East, the turtles and tortoise have a special role that is usually linked with life after death," Berthon explained. What's surprising here, he said, is that these special powers may have been applied to soft-shelled turtles, an overlooked animal today. As there are no marks of trauma or injuries, it's not clear how the two people buried with the turtles died. But the strange burial —and the evidence for a possible funeral feast —might also indicate that these two had high social status or symbolic status.

The findings were published online Feb. 17 in the journal Antiquity.

Follow us @livescience, Facebook & Google+. Original article on Live Science.

Avi Shuter is a wild-animal keeper at the Wildlife Conservation Society's (WCS) Bronx Zoo Herpetology Department. Julie Larsen Maher is staff photographer for WCS. In addition to documenting WCS field work, Maher photographs the animals at WCS's five New York-based wildlife parks: the Bronx Zoo, Central Park Zoo, New York Aquarium, Prospect Park Zoo and Queens Zoo. The authors contributed this article to Live Science's Expert Voices: Op-Ed & Insights. 

Turtles have been around for nearly 200 million years. They watched the dinosaurs go extinct and saw human beings take their place. But today, many turtle species are threatened with their own demise: More than half of the world's approximately 341 species of freshwater turtles and tortoises are on the brink of extinction. Some species have even become "functionally extinct," which means that though there may be some individuals left in the wild, the population is too small to be self-sustaining. 

The factors contributing to these declines are numerous and span the globe: pollution, hunting, habitat destruction and overcollection for the pet trade. In addition, wildlife trafficking is causing the eradication of more and more species worldwide. Much of the world's turtle trade is driven by demand from China, specifically for human consumption and for use in traditional medicines.

As part of WCS's commitment to help threatened turtles and tortoises , the Bronx Zoo's Department of Herpetology houses 12 of the 40 most endangered turtles and tortoises in the world. All of them are on the International Union for Conservation of Nature (IUCN) Red List. Some species are part of coordinated breeding efforts resulting in successful hatchings of turtles and tortoises, some no larger than a quarter. (Credit: Julie Larsen Maher ©WCS.)

Chinese Yellow-headed Box Turtle Hatchling

Chinese yellow-headed box turtles were once plentiful in the highlands of the Anhui province of eastern China. Their population collapsed due to human consumption, use in traditional medicine, pollution, habitat loss and the pet trade. When these turtles hatch they are tiny, weighing about 10 grams.

Egyptian Tortoise

Egyptian tortoises have disappeared from their namesake nation due to loss of habitat and collection for the pet trade. This is the second-smallest species of tortoise in the world, and they do not reach sexual maturity until they are 10 to 20 years old.

Golden Coin Turtle Hatchling

The golden coin turtle eats a more varied diet than its cousin, the Chinese yellow-headed box turtle. It eats vegetation, small insects, arthropods and fish. 

McCord's Box Turtle

The natural range of the McCord's box turtle is mostly undiscovered. The species is predominantly known from its availability in Chinese markets. 

Mary River Turtle

Mary River turtles are endangered, short-necked turtles with a remarkable adaptation: They perform "cloacal breathing." In most species, the cloaca (or the turtle's "back side") is the posterior opening that serves as the only orifice for waste and reproduction. However, the Mary River turtle can also use its cloaca to absorb oxygen directly from water.

Roti Island Snake-necked Turtle Hatchling

Roti Island snake-necked turtles live in the swamps and lakes found on the tiny island of Roti in Indonesia. Their necks fold sideways rather than straight back when they pull into their shells. These turtles have been over-collected for the pet trade and are critically endangered.

Radiated Tortoise Hatchling

Madagascar's radiated tortoises have all but disappeared from their island home due to habitat loss, hunting for their meat, and collection for the pet trade. The females lay from three to 12 eggs, which resemble Ping-Pong balls. The hatchlings have beautiful, roundish shells and, at 1.5 inches, are miniature versions of their 35-pound parents. [Shell Shock: 25 Turtle Species in Terrible Trouble]

Sulawesi Forest Turtle

Sulawesi forest turtles are critically endangered.

Sulawesi Forest Turtle

Trade in East Asia markets has decimated their population, which is found only on the remote Indonesian island that gives this turtle its name.

Read more stories on turtles, tortoises and other wildlife in Wild View by Avishai Shuter and Julie Larsen Maher.

Follow all of the Expert Voices issues and debates — and become part of the discussion — on Facebook, Twitter and Google+. The views expressed are those of the author and do not necessarily reflect the views of the publisher. This version of the article was originally published on Live Science.

Paging Charles Darwin: The island of Santa Cruz within the Galápagos has not one but two distinct species of giant tortoise, a new genetic study finds.

For years, researchers thought that the giant tortoises living on the western and eastern sides of Santa Cruz belonged to the same species. But the tortoises look slightly different, and so recently, scientists ran genetic tests on about 100 tortoises from both groups.

The tests were definitive: The two tortoise populations, which live only about 6 miles (10 kilometers) apart on the opposite sides of the island, are actually extremely distant relatives. [Image Gallery: Fossilized Turtles Caught in the Act]

The Santa Cruz tortoise species that has long been called Chelonoidis porter are the ones living on the western side, in a region of the island known as La Reserva. And now, the newly identified eastern Santa Cruz tortoise has been named Chelonoidis donfaustoi. It inhabits an area known as Cerro Fatal. 

"We immediately found that [the eastern tortoises] were very distinct from the other ones," said the study's senior author, Adalgisa Caccone, a senior ecology and evolutionary biology research scientist at Yale University. "As distinct as species from different islands."

In fact, the two species evolved millions of years apart. The western tortoises are part of the oldest giant tortoise lineage in the Galápagos, which evolved about 1.74 million years ago. In contrast, the eastern tortoises are much younger — they evolved less than half a million years ago. The genetic tests showed that the eastern tortoises are more closely related to tortoises found on other Galápagos Islands than they are to the tortoises living on the western side of their own island, the researchers found.

The finding may change how scientists approach the conservation of tortoises in the Galápagos, Caccone told Live Science. Right now, the western Santa Cruz tortoise population is booming, with about 2,000 members, whereas the eastern species has only about 250 individuals, Caccone said. Now that researchers know the eastern group is a separate species, it may receive increased habitat protection, she said.

The  discovery of the new species "will help these tortoises receive the scientific and management attention they need to fully recover," James Gibbs, a co-author of the study and a conservation biologist at the SUNY College of Environmental Science and Forestry in Syracuse, said in a statement.

The name of the new species honors Fausto Llerena Sánchez, a Galápagos National Park ranger who spent 43 years caring for endangered tortoises in captivity.

"His dedication to his work has been inspirational," Gibbs said.

The populations of giant tortoises in the Galápagos have dropped to historic lows, largely because of human exploitation, invasive species and habitat degradation, the researchers said.

The findings were published online today (Oct. 21) in the journal PLOS ONE.

Follow Laura Geggel on Twitter @LauraGeggel. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.

Below the tropical waves near the Solomon Islands, nighttime divers spotted a psychedelic vision: an endangered sea turtle glowing bright red and green.

The divers immediately began filming the creature, a hawksbill sea turtle (Eretmochelys imbricate), following it for a few minutes until it swam away.

"It was such a short encounter," said David Gruber, an associate professor of biology at Baruch College in New York City and a National Geographic emerging explorer. "It bumped into us and I stayed with it for a few minutes. It was really calm and letting me film it. Then it kind of dove down a wall, and I just let it go." [See Images of Glowing Sea Turtle and Other Light-Emitting Creatures]

The finding is an important one: Though researchers have already found biofluorescence in aquarium-housed loggerhead sea turtles (Caretta caretta), this is the first time scientists have identified biofluorescence in a reptile in the wild, Gruber told Live Science.

Biofluorescence occurs when an organism absorbs light from an outside source, such as the sun, transforms it and then reemits it as a different color. (This is different from bioluminescence, a chemical reaction that helps creatures, such as fireflies, flash light. Some animals also host bioluminescent bacteria, such as flashlight fish.)

The field of biofluorescence has taken off in the past decade, with researchers identifying all sorts of biofluorescent marine animals, including corals, fishes, eels and sharks. The work is so groundbreaking that Gruber and his colleagues helped make a forthcoming Nova special called "Creatures of Light," he said.

Turtle time

The divers weren't looking for glowing sea turtles on July 31, Gruber said. They had waited until nightfall — luckily they had a full moon — and took a boat to shallow water near Nugu Island, located in the Solomon Islands in the South Pacific. Recent news of crocodile attacks had them on guard, but they dove into the water, and used blue lights to look for biofluorescent sharks.

Then, the turtle came along.

"This turtle almost seemed completely attracted to the blue lights that we were filming with, and just swam right into me," Gruber recalled.

Under the blue lights, the turtle fluoresced "a brilliant green," on its head, flippers and plastron (the underside of its shell), he said.

The shell glowed both red and green, but it's likely the red came from biofluorescent algae, Gruber said.

"This turtle was just hanging out with us. It was in love with the lights," Markus Reymann, the other diver and the director of TBA21-Academy, a group that pairs artists and scientists together, said in a National Geographic video. "And it was glowing neon yellow."

Gruber later showed the film to Jeanette Wyneken, a professor of biology at Florida Atlantic University. From the looks of it, the 3-foot-long (1 meter) turtle looks like a female that is nearing adulthood, she told him.

Gruber also spoke to some locals who kept captive juvenile hawksbill sea turtles, and found that they fluoresced green under a blue light. [The 7 Weirdest Glow-in-the-Dark Creatures]

Critically endangered

The hawksbill turtle breeds in more than 80 countries and is found in the Caribbean Sea and Indo-Pacific Ocean, but it's also critically endangered, partly because of climate change, illegal trade, bycatch (in which commercial fishers catch turtles by mistake while collecting other fish) and hunting, Gruber said.

"The Solomon [Islands] are one of the places where there's a large rookery of them," he said. "It's like a little hotspot where the hawksbills are still very healthy."

But it's difficult to study a critically endangered animal. Instead, Gruber says he'll probably study biofluorescence in the loggerhead turtle first, just because they're more accessible.

Still, it's anyone's guess why turtles would need to glow.

"It could be a way for them to communicate, for them to see each other better, [or] to blend into the reefs," which are also biofluorescent, Gruber said. "It adds visual texture into the world that's primarily blue."

Follow Laura Geggel on Twitter @LauraGeggel. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.

An ancestor of modern-day turtles, a shell-less creature with a long tail once puttered around an ancient lake, likely munching on insects and worms with its peglike teeth, a new study finds.

Researchers found the first fossils of the 240-million-year-old creature in 2006, during an excavation of Vellberg Lake, an ancient lakebed in southeastern Germany, said study researcher Hans Sues, a curator of vertebrate paleontology at the Smithsonian Museum of Natural History in Washington, D.C.

"We now have well over a dozen specimens, including partial skeletons but also some isolated parts of skeletons," Sues told Live Science. "But we have a nice spectrum of sizes, so you can sort of see how the animal grows and changes." [Image Gallery: Fossilized Turtles Caught in the Act]

The researchers named the new species Pappochelys rosinae, from the Greek words "pappos" meaning grandfather — as the species is thought to be the "grandfather" of shelled turtles — and "chelys," meaning turtle. The species name honors I. Rosin, who prepared key specimens of the new taxon, Sues said.

P. rosinae was small, measuring about 8 inches (20 centimeters) long, but it fills in an important evolutionary gap, the researchers said.

"It's a beautiful link between the earliest precursors that we know of turtles, this animal called Eunotosaurus from South Africa that lived about 260 million years ago, and then later turtles that had a fully developed shell," Sues said.

P. rosinae has broad trunk ribs, and belly armor made of thick, riblike structures. Coincidentally, researchers studying turtle evolution have hypothesized that turtle ancestors once had riblike structures such as these, as well as protective bones on the shoulder girdle, Hans said.

"Our new fossil beautifully confirms that," he said.

Turtle evolution

The P. rosinae fossils hold other clues about turtle evolution. The creature's skull has two small holes behind the eye sockets on either side, a feature seen in many reptiles today — though not modern turtles, making it difficult to understand the animal's evolutionary lineage.

Some scientists hypothesized that turtles had an ancient lineage and evolved from the base of the reptilian tree. In contrast, some molecular researchers suggested that turtles were more closely related to these so-called two-holed "diapsid" reptiles than to the earliest reptiles, which didn't have any openings at all, Sues said.

"This new fossil shows that the molecular people were actually right," he said. "It shows that turtles are closely related to other modern reptiles and didn't branch off early."

A reptilian tree analysis showed that turtles are more closely related to lepidosaurs, such as lizards and snakes, than they are to archosaurs, such as nonavian dinosaurs and birds, according to the study.

The researchers said they hope to paint a fuller picture of turtle evolution as more fossils emerge. The first fossil on record of a fully shelled turtle (Proganochelys) dates to between 205 million and 210 million years ago, Sues said. However, the creature couldn't withdraw its head and neck into its shell.

"What they did instead was they put armor on their head and neck to protect themselves," he said. [In Photos: Bones Reveal Ancient Sea Turtle]

Modern turtles, with the exception of sea turtles, can all withdraw their heads and necks into their shells in one of two ways: Most living turtles, such as tortoises, draw their necks back in an S-shape. However, a smaller group of turtles, such as the side-necked river turtle, draw their necks back sideways to hide them under the edge of their shells, Sues said.

The study was published online today (June 24) in the journal Nature.

Follow Laura Geggel on Twitter @LauraGeggel. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.

Rachel Ewing is a news officer for science and health at Drexel University. She contributed this article to Live Science's Expert Voices: Op-Ed & Insights. 

When an amateur collector brought a strange, heavy fossil to the New Jersey State Museum, paleontologists David Parris and Jason Schein never imagined the surprise it had in store.

They recognized the fossil as a humerus — the large upper arm bone — from a turtle, but one that had broken in half so only the distal, elbow-connected end remained. 

Parris also thought the fossil looked familiar. He thought the resemblance to a fossil he had studied years earlier in the collections at the Academy of Natural Sciences of Drexel University was coincidental. That turtle humerus had only the shoulder end of the bone. 

But conventional wisdom held that they couldn't possibly be the same bone. The older specimen, discovered in 1849 or earlier, was much too old. Its missing half should have deteriorated from exposure within decades.

The academy's older bone was also one of a kind: It was the first, and to that date only, specimen of its genus and species (Atlantochelys mortoni). [Photos: Butterflies Drink Turtle Tears ]

Until the day Schein carried the newfound fossil to the academy in Philadelphia.

"As soon as those two halves came together, like puzzle pieces, you knew it," said Ted Daeschler, the academy paleontologist who helped Schein verify the surprising find. 

The two halves were parts of the same bone. One half was collected at least 162 years before the other. 

In addition to overturning conventional wisdom, the fully assembled bone made it possible to calculate that this animal was one of the largest sea turtles ever known, about 10 feet from tip to tail. 

Follow all of the Expert Voices issues and debates — and become part of the discussion — on Facebook, Twitter and Google+. The views expressed are those of the author and do not necessarily reflect the views of the publisher. This version of the article was originally published on Live Science.

Bone-eating worms that can devour an entire whale carcass were also feasting on prehistoric reptiles more than 100 million years ago, a new study finds.

No one knows when the first Osedax worms started scavenging sunken carcasses on the ocean floor. The bizarre, finger-length worms are soft-bodied and leave no fossils behind, so their origin is lost to time. But traces of the creatures' strange dining habits can be detected on ancient fossils.

Osedax not only feast on dead whales today, the worms also bored into 100-million-year-old plesiosaur and sea turtle bones, scientists from Plymouth University in the United Kingdom report today (April 14) in the journal Biology Letters.  [The 12 Weirdest Animal Discoveries]

Treasure hunt

Paleontologist Silvia Danise hunted through gnarly bones in the drawers and displays of the Sedgwick Museum in Cambridge to find fossils gnawed by Osedax. "I was looking for things that were weathered, or with an irregular surface, which is what happens in the modern bones that are attacked by Osedax," said Danise, lead study author, who is now at the University of Georgia in Athens.

Bone-eating worms are amazingly effective eaters for creatures with no mouths or guts. (Some species use acid instead.)  The worms were discovered in 2002 on the seafloor offshore California, gorging on a whale. How the worms eat remains a mystery, but scientists think the creatures extend fleshy tendrils laced with symbiotic bacteria into the bone. The tendrils carve through the nutrient-rich tissue and extract collagen and fat with help from the bacteria. This eating action leaves behind an empty pocket that resembles a tree stump with roots.

Danise hit pay dirt with several old bones from the end of the Mesozoic era, before the Cretaceous mass extinction that killed off the dinosaurs and the plesiosaurs 65 million years ago. There were distinctive round boreholes and rootlike cavities in bones from turtles and plesiosaurs (bus-size, flippered marine reptiles).

With co-author Nicholas Higgs, Danise scanned the fossils with micro-CT (similar to a medical imager) to confirm each bone carried the worm's characteristic cavity. The fossil holes were nearly identical to bones munched by modern Osedax worms, and also a good match to more recent fossils, the study reported.

"They've done a wonderful job here," said Robert Vrijenhoek, a marine biologist at the Monterey Bay Aquarium Research Institute in Moss Landing, California, who first discovered boneworms. Vrijenhoek was not involved in the new research. "They've really nailed it, and I'm thrilled," Vrijenhoek told Live Science.

Setting the clock

The fossils can now be used to calibrate genetic evidence, called a "molecular clock," which suggests Osedax worms first emerged during the Mesozoic about 125 million years ago, Vrijenhoek said. An alternate model had Osedax appearing with the first whales some 45 million years ago. A better molecular clock will also help researchers who study the bone-eating worm's relatives, such as the strange pink and red worms that thrive at deep-sea hydrothermal vents.

And researchers are still finding new Osedax species around the world to add to the family tree, with 17 new worm species discovered in California's Monterey Canyon in recent years, said Greg Rouse, a marine biologist at the Scripps Institution of Oceanography in La Jolla, California.

"We are still barely scratching the surface of their diversity," said Rouse, who was not involved in the study. "It's just an amazing innovation by animals to exploit a food resource."

The new findings also lend support to the idea that Osedax is an opportunistic eater. After the Cretaceous extinction, big marine vertebrates disappeared from the oceans until the first whales swam the seas. During this 20-million-year gap, Osedax survived on the carcasses of large fish and sea turtles, the fossils suggest.

"It doesn't matter if it's a dinosaur, a turtle or a fish, bone composition is always the same," Danise said.

Follow Becky Oskin @beckyoskin. Follow Live Science @livescience, Facebook & Google+. Originally published on Live Science.

A huge sea turtle found stranded on a remote South Carolina beach over the weekend was returned to the wild today (March 12).

The nearly 500-lb. (215 kilograms) leatherback turtle was rescued Saturday (March 7) on Yawkey-South Island Reserve, a barrier island near Georgetown, suffering from low blood sugar and exhaustion. State wildlife officials said it took five people to lug the teenage turtle off the beach and onto a wood platform specially built to carry it to the South Carolina Aquarium's Sea Turtle Hospital in Charleston. 

The rare leatherback shuffled back into the Atlantic under its own power Thursday afternoon, on a sandy beach in Isle of Palms, South Carolina. The aquarium kept the release secret to ensure the turtle's safety, said Kate Ditloff, the aquarium's public relations manager. [See Photos of the Incredible Leatherback Turtle Rescue]

The endangered reptile is the first of its kind ever rescued alive in South Carolina, and one of only a handful of live leatherback rescues in the United States, according to the South Carolina Department of Natural Resources. Leatherback sea turtles migrate northward along the East Coast during spring and are currently nesting offshore Florida. 

Named Yawkey, the turtle was treated for its low blood sugar and a possible intestinal blockage, and also received vitamins and antibiotics to combat any possible infections. Biologists estimated that Yawkey is about 10 to 15 years old.

Because leatherbacks fare poorly in captivity, aquarium staff planned to release the rescued turtle as soon as possible, aquarium representatives said earlier this week. Yawkey was acclimated to cool water temperatures and tagged with a microchip and flipper tags before the turtle's release, they said.

The leatherback turtle is the largest of all turtles and one of the largest living reptiles. They are named for their shell, which is a leathery carapace instead of the hard shell found on other turtle species. The leatherback's big body, large flippers and light carapace are designed for long-distance ocean travel. Adults live in the open ocean, and populations in the Pacific and Atlantic Oceans regularly cross back and forth between continents, from nesting sites to feeding areas.

The Pacific and Southwest Atlantic leatherback populations are considered critically endangered and are protected under the federal Endangered Species Act.

Leatherbacks feed almost exclusively on soft-bodied ocean creatures, such as jellyfish and squid, and often mistake floating plastic bags for their favorite food. Swallowing the bags can kill them. Sea turtles are also often caught in fishing gear, which traps them below the surface, where they drown. People also harvest leatherback eggs for food, which has decimated their population in some regions.

Follow Becky Oskin @beckyoskin. Follow Live Science @livescience, Facebook & Google+. Originally published on Live Science.

Wildlife experts rescued a stranded leatherback turtle in South Carolina on March 7.  The 475-pound (215 kilograms) teenage turtle was the first leatherback ever rescued alive in South Carolina. It took five people to lift the leatherback from the beach and bring it to the South Carolina Aquarium's Sea Turtle Hospital in Charleston.  [Read the full story on the leatherback rescue.]

The turtle was named Yawkey, after the remote beach in Yawkey-South Island Reserve where it was found.

Rolling the leatherback up a ramp into the aquarium hospital.

Biologists checked the leatherback for injuries. The turtle is thought to be between 10 to 15 years old.

Leatherback turtles are the largest of all turtles and can weigh as much as 2,000 pounds (907 kilograms).

Yawkey the turtle received antibiotics to combat any infections.

After the checkup, Yawkey recovered in a small pool.

As of March 10, Yawkey was improving and regaining energy.

On March 12, aquarium staff prepped Yawkey for release into the wild.

The rare turtle was released on the Isle of Palms, South Carolina.

Yawkey was acclimated to the cool ocean temperatures offshore before the turtle's release.

Follow Becky Oskin @beckyoskin. Follow Live Science @livescience, Facebook & Google+. 

Brian Horne is coordinator of turtle conservation for the Wildlife Conservation Society (WCS). WCS manages the Bronx Zoo, the New York Aquarium and other sites, in addition to its global conservation work. Horne contributed this article to Live Science's Expert Voices: Op-Ed & Insights. 

Turtles are popularly perceived as slow, lumbering animals, typically found alone and seemingly unaware of their surroundings. The spectacle of marine turtles hauling themselves out of the surf to lay a hundred or so eggs ends with an image of them returning to the ocean, never to see their offspring again. 

The concept of a turtle caring for and communicating with a hatchling perhaps one hundredth her size is the stuff of children's stories and films like "Finding Nemo."  

Yet the assumption that all turtles leave their young to fend for themselves may not be the case with every species. A team of researchers in Brazil recently found that indeed some turtles do "talk," and females are at least associating with hatchlings after they leave the nest — and even as the hatchlings travel hundreds of kilometers along the Amazon.  

Turtle talk

The mewling of newborn kittens is a familiar sound, but now we find that giant South American river turtle hatchlings make sounds before they exit their eggs, and continue to do so even as they clamber out of the nest chamber onto the river beach. The underwater vocalizations of the responding adult turtles may likewise help the newly-hatched turtles find their way once they are in the water . 

Scientists Camila Ferrara of the WCS and Dick Vogt of the Instituto Nacional de Pesquisas de Amazônia have scientifically documented turtles producing a limited repertoire of clicks and clucks at very low frequencies. By using low frequencies, the turtles are able to produce sounds that travel long distances underwater. 

Serving the species

Turtle conservation for many decades has been focused on how to best produce the most hatchling turtles with little thought about relationships between the hatchlings and the parents.  

Conservationists have at times moved nests many miles from their original location in hopes of higher hatch rates. At other times, they have kept hatchlings in captivity for short periods of time so that they can grow to a size that minimizes their risks of being eaten by a predator.  

But what these biologists haven't considered is how these well-intended actions may disrupt important audible communication cues, as the recent findings on the surprising behavioral complexity of the giant South American river turtle may suggest. Perhaps with this species, environmental factors necessitate parental guidance.

Thousands of miles long and in places miles across, the Amazon is a massive river on a scale that is hard to grasp. Imagine being a hatchling turtle weighing just a few ounces and confronting that enormous expanse alone. 

If the research done by Ferrara and Vogt holds true, it appears that mother turtles are actually waiting for the eggs to hatch before guiding the tiny hatchlings into rich foraging areas. This unprecedented discovery may greatly shape turtle conservation around the globe. 

Saving social turtles

In 2011, WCS worked with the Turtle Survival Coalition to document the 25 most endangered turtle species on Earth. Many of my current conservation activities occur in Asia, where large river turtle populations have been decimated — in some cases down to just a handful of adult animals remaining in the wild. My colleagues and I have relied heavily on head-starting — incubating eggs and hatching turtles in captivity before their release into the wild — to boost populations and prevent individual species from going extinct. 

What we have not been doing is investigating the importance of social behavior in the survivorship of the head-started turtles once they are released back into the wild. [Shell Shock: 25 Turtle Species in Terrible Trouble ]

We always assumed we were truly giving turtles a "head-start" in their effort to survive because predation appeared to be the greatest challenge to their conservation. But what if by head-starting the turtles, we have been preventing them from learning important migratory behaviors from the adult population?  

How can we rectify this? Do we need to play underwater recordings of adults during the time the turtles are being raised? Do we need to train the turtles to follow recordings to important foraging areas?

Through the use of a hydrophone listening instrument, I hope to begin unraveling this latest mystery in my next research project. Only time will tell what precisely is taking place. But one thing we know already: our understanding of how turtles survive in their respective environments, and how hatchlings may benefit from parental care, may never be the same again.

Follow all of the Expert Voices issues and debates — and become part of the discussion — on Facebook, Twitterand Google+. The views expressed are those of the author and do not necessarily reflect the views of the publisher. This version of the article was originally published on Live Science.

Swimming to safety

Oceana contributed these images to Live Science’s Expert Voices: Op-Ed & Insights.

Loggerhead turtles are some of the most threatened animals in U.S. waters. From birth through adulthood, the sea turtles face a wide range of threats from humans: oil slicks, fishing lines and nets, boaters, and even light pollution that disrupts the hatchlings' march to the sea.

However, last week their fortunes changed — the National Marine Fisheries Service and the U.S. Fish and Wildlife Service made a joint announcement to designate 685 miles of beaches and more than 300,000 square miles of ocean as protected habitat, the largest protected "critical habitat" in the nation.

Read more about the new habitat protections in, “Largest-Ever U.S. Critical Habitat Set for Loggerheads,” and view stunning images of loggerheads in the gallery that follows.

Taking a dive

A loggerhead turtle is followed by a fish shoal.

Time for a breather

A loggerhead turtle at the surface getting air.

Starting the journey

A loggerhead sea turtle hatchling (Caretta caretta) heading to sea in Bald Head Island, N.C.

Hey, there!

A loggerhead sea turtle swimming in the Rivera Maya in Mexico.

Home once again

A loggerhead nesting on Bald Head Island, N.C.

Follow all of the Expert Voices issues and debates — and become part of the discussion — on Facebook, Twitter and Google +. The views expressed are those of the author and do not necessarily reflect the views of the publisher. This version of the article was 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.

You might have seen in recent news that climate change may increase the size of some sea turtle populations, by increasing the number of female turtles.

These studies hinge on an unusual trait of sea turtles: their sex is determined by the temperature in the nest. Turtle eggs incubated above 29C produce mostly females, while temperatures under 29C produce mostly males.

Our recent study published in Nature Climate Change found that by altering the sex ratio of turtle populations in favour of females, climate change could lead to a population increase in the short term. But this isn’t the whole story.

Warmer eggs make more females

The study found that rising temperatures might alter sex ratios and increase the size of some sea turtle populations.

Sea turtles are unusual in that the sex of hatchlings is determined, not by sex chromosomes (as is the case in humans and other mammals), but by incubation temperature, a phenomenon known as temperature-dependent sex determination.

Above a certain pivotal incubation temperature of 29C, the majority of sea turtle eggs produce female hatchlings, and vice versa. This pivotal temperature holds broadly for all sea turtle species and has presumably evolved to produce optimally balanced sex ratios.

So warming temperatures may cause the feminisation of sea turtle populations through the production of only female hatchlings. Previous studies have highlighted how, all else being equal, this feminisation effect might lead to population extinctions.

However, while this threat of feminisation of sea turtle populations has been known for many years, there had previously been few attempts to predict how the sex ratio of populations may change in the future, and the resulting extinction risk.

The study, undertaken by an international team including scientists from Deakin University in Warrnambool (Australia) and Swansea University (UK) took place in one of the world’s largest sea turtle rookeries, the Cape Verde Islands in the Atlantic, where large numbers of loggerhead turtles breed. It recorded sand temperatures on nesting beaches over several years using small data-loggers.

These sand records were then combined with past measurements of environmental conditions on these islands since 1850, and climate predictions for the next 100 years made by the Intergovernmental Panel on Climate Change (IPCC). In this way a robust two hundred and fifty year time-series of incubation temperatures, hatchling sex ratios, and adult breeding sex ratios were derived.

The research found that increased temperatures would lead to increased feminisation of the species, but entire feminisation would not be imminent in the next few decades. In fact, warm incubation temperatures may have a short-term conservation benefit on the turtles, increasing the number of breeding females and hence the total size of the population

Climate change still bad for turtles

However, the study is not complete. There is much more work to be done to understand how sea turtles will be affected by climate change.

The study focused on one site in the Atlantic. There is a need to extend the study to further examine the threat of feminisation for sea turtles at their many other nesting sites around the world, including around the coast of Australia which is home to key populations of several species.

By extending these analysis methods, we can objectively identify those areas where climate change and feminisation of populations are likely to be most acute. In this way we can have an early warning for where future management intervention may be required, for example, in the form a shading nests to ensure that males are produced.

Further, as the number of males decreases, they are going to become ever more important and yet we know very little about them. Unlike females, male sea turtles do not come ashore and so are hard to study. While thousands of adult female turtles have been equipped with satellite tags, only a handful of adult males have been tracked.

There is an important knowledge gap here. We have started to address this gap by catching male turtles at sea and equipping them with satellite tags. In this way we have collected data giving an indication that males may breed more frequently than females. This finding suggests that skewed female hatchling sex ratios will actually translate to more balanced sex ratios of breeding males and females. More studies of breeding intervals need to be undertaken across different species and in different breeding locations.

So while the recent research provides some useful insights into how climate might impact sea turtles, a host of questions remain. The long-term prognosis for sea turtles in a warming world is not necessarily good.

Graeme Hays receives funding from Deakin University and Swansea University. He works for Deakin University and Swansea University.

This article was originally published on The Conversation. Read the original article. Follow all of the Expert Voices issues and debates — and become part of the discussion — on Facebook, Twitter and Google +. The views expressed are those of the author and do not necessarily reflect the views of the publisher. This version of the article was originally published on Live Science.

Tag, You're It!

A young loggerhead turtle raised at the Gumbo Limbo Nature Center in Boca Raton, Fla. to be tagged and tracked on its migration around the Atlantic. (NMFS Permit 1551)

Satellite Tag

A satellite tag and attachment. Advances in technology and solar power enable researchers to tag smaller turtles. (NMFS Permit 1551)

Tagged Turtle

A young loggerhead turtle with a satellite tag affixed to its shell. (NMFS Permit 1551)

Tag and Release

A young loggerhead sea turtle tagged and ready for release. (NMFS Permit 1551)

Preparing to Release

Researcher Jeanette Wyneken holds a young loggerhead sea turtle. (NMFS Permit 1551)

Sea Turtle Free

A young sea turtle tagged with a satellite tag and freed into the Gulf Stream. (NMFS Permit 1551)

Ready to Migrate

A young loggerhead turtle affixed with a satellite tag and ready to begin its Atlantic migration. (NMFS Permit 1551)

Pretty Swimmer

The tagging study found that young turtles take many paths in their Atlantic migration, with many dropping out of the ocean gyre and into the still Sargasso Sea. (NMFS Permit 1551)

Swimming Turtle

Young loggerhead turtles swims up the Gulf Stream from southeastern Florida. (NMFS Permit 1551)

Surfacing Turtle

Satellite data shows that loggerhead sea turtles spend lots of time on the surface. (NMFS Permit 1551)

Ready to Go

Two turtles in a basket, awaiting their release into the Gulf Stream. (NMFS Permit 1551)

LOS ANGELES — More than 70 million years ago, a baby shark may have bitten off more than it could digest.

A fossilized hunk of poop from an ancient baby shark has revealed the tiny predator's last meal: a baby turtle. The findings were presented here at the 73rd annual meeting of the Society of Vertebrate Paleontology.

"It's a case where a newborn shark ate a newborn turtle and died," said study co-author David Schwimmer, a paleontologist at Columbus State University in Georgia.

The 1.5-inch-long (3.8 centimeters) piece of fossilized poop, technically known as a coprolite, was found at a fossil bed near the South Carolina coastline. Between 70 million and 80 million years ago, when the poop's owner lived, the area was a tidal estuary where the ocean met inland river systems. [8 Weird Facts About Sharks]

Based on the size of the coprolite, Schwimmer and his colleagues hypothesize that the shark that ejected it was a newborn. Inside the coprolite were several tiny turtle vertebrae, each about 0.1 inches (about 3 millimeters) long, which must have come from a very young turtle.

The vertebrae suggest the turtle is a soft-shell freshwater species, whereas the shark comes from a marine environment. Based on that information, Schwimmer believes the shark may have emerged from an estuarine pupping ground, where baby sharks hatched. Once the newborn shark emerged, it devoured the unsuspecting newborn turtle.

The turtle was probably about 4 inches (10 cm) across, while the shark may not have been much bigger. The fact that the vertebrae were undigested indicates the baby predator died not long after eating, possibly because its last meal didn't sit well with the animal, Schwimmer said.

"It's possible the turtle was too much shell," Schwimmer told LiveScience. The shark "may have died from too much turtle."

Though Schwimmer hasn't determined the shark and turtle species, one possibility is that the shark may be the extinct coastal predator Squalicorax kaupi. The turtle may have been a relative to common freshwater species that are found in the region today.

This isn't the first time paleontologists have gleaned something from ancient shark poop. Other shark coprolites have revealed that sharks dealt with tapeworms even 270 million years ago, and fossilized dung from other animals can reveal their dietary habits. 

Follow Tia Ghose on Twitter and Google+. Follow LiveScience @livescience, Facebook & Google+. Original article on LiveScience.

Drinking tears

Butterflies in the Amazon have been observed flocking onto the heads of turtles to drink their tears, which provide the animals with a vital source of the mineral sodium.

Two on one

Here are several butterflies going after a single yellow-spotted river turtle. The turtle's tears contain salt, specifically sodium, an important mineral that is scant in the western Amazon.

Blinded by butterflies

The western Amazon is lower in sodium than many places on Earth, because it is more than 1,000 miles (1,600 kilometers) from the Atlantic Ocean, a prime source of salt, and is cut off from windblown mineral particles to the west by the Andes Mountains. Dust and minerals make their way into the Amazon from the east, sometimes all the way from north Africa. But much of this material is removed from the air by rain before it reaches the western Amazon, said Phil Torres, a conservation biologist who does much of his research at the Tambopata Research Center in Peru.

Buzz off

Bees can also be attracted to the turtles. They appear to annoy the animals more than butterflies, perhaps because of their buzzing wings, Torres said.

Turtles in a row

Unlike butterflies, turtles get plenty of sodium through their carnivorous diet. Meat contains significant levels of the salt, Torres told LiveScience. But herbivores sometimes struggle to get enough sodium and other minerals, he added. "They end up needing this extra mineral source," he said.

Puddling

Turtle tears are not the only source of such salts for butterflies; the insects also readily get the salt from animal urine, muddy river banks, puddles, sweaty clothes and sweating people, said Geoff Gallice, a graduate student of entomology at the Florida Museum of Natural History, who has witnessed butterflies flocking to turtle tears in the western Amazon rain forest. Here butterflies are witnessed "puddling," gathering minerals from mud.

Obstructed vision

One question that arises: Does the butterfly feeding help, hurt or have no impact on the turtles? Torres said it's not completely clear, but the teary endeavor probably has little impact on the turtles, other than perhaps making them more vulnerable to predators like big cats, since the butterflies can obstruct their vision.

Easier to photograph

In fact, the turtles — blinded and drowning in butterfly kisses — are sometimes easier to photograph than unadorned animals, which may be able to spot an approaching photographer more easily. The photos were taken by Jeff Cremer, marketing director for Rainforest Expeditions, an ecotourism company that hosts guests in the Peruvian Amazon and organizes trips to the jungle.