11 Fascinating Facts About the Frilled Shark

Sometimes called a “living fossil” because it has changed so little since prehistoric times, the eel-like frilled shark—which is rarely seen by humans—has been in the news this week after a snake-like one was found off the coast of Portugal. Here’s a quick primer.

1. IT’S NAMED FOR ITS GILLS.

Its scientific name is Chlamydoselachus anguineus, but this creature’s common name comes from its gills: Unlike all other sharks, which have separate gills, C. anguineus’ first pair of gills go all the way across its throat; each pair is lined at the edges with red “fringe.”

2. IT WAS DISCOVERED IN THE 19TH CENTURY.

The sharks were first scientifically described by German ichthyologist Ludwig H.P. Döderlein, who taught at Tokyo University from 1879 to 1881 and brought two specimens captured in Tokyo Bay when he returned to Vienna. His paper describing the sharks was lost, however, so the first description comes from Samuel Garman in the 1884 edition of the Bulletin of Essex Institute. In the remarks after the description, Garman noted that

Such an animal as that described is very likely to unsettle disbelief in what is popularly called the “sea serpent.” Though it could hardly on examination be taken for anything but a shark, its appearance in the forward portion of the body, particularly in the head, brings vividly to mind the triangular heads, deep-cleft mouths, and fierce looks of many of our most dreaded snakes. In view of the possible discoveries of the future, the fact of the existence of such creatures, so recently undiscovered, certainly calls for a suspension of judgment in regard to the non-existence of that oft-appearing but elusive creature, the serpent-like monster of the oceans.

The frilled shark’s species name, anguineus, is Latin for “consisting of snakes” or “snaky.”

Biologist David A. Ebert, director of the Pacific Shark Research Center, described a second frilled shark species—Chlamydoselachus africana, which lives off the coast of Africa and is about half as long as its predecessor—in 2009.

3. IT’S GOT INSANE TEETH.

The frilled shark’s mouth is just as terrifying as the maw of a great white: It’s lined with 25 rows of backward-facing, trident-shaped teeth—300 in all. “The teeth are constructed for grasping and from their peculiar shape and sharpness it would seem as if nothing that once came within their reach could escape them,” Garman wrote. “Even in the dead specimen the formidable three-pronged teeth make the mouth a troublesome one to explore.” 

Ebert can testify to that fact. “I can tell you from snagging my fingers on the teeth, you can only back out one way and that’s in toward the mouth and then out,” he told WIRED. “It didn’t feel good, I can tell you that.” The shark uses the bright white teeth, which sharply contrast against its brown body, to lure in prey: “By the time [the prey] realize, Oh, that’s the teeth of a shark, they’re too close and the shark is able to ambush them at that point,” Ebert said. “It’s almost like when you drive out of a parking lot exit and they have the spikes sticking out that say, ‘Do not back up.’ That’s kind of what happens when these things catch prey items.”

And as if its teeth weren’t freaky enough, the frilled shark has spines, called dermal denticles, lining its mouth. So if you happen to see one of these anywhere, it’s better to look and not touch.

4. IT “HOVERS” IN THE WATER...

Scientists once believed that the frilled shark wriggled through the water like an eel. But according to the ReefQuest Centre for Shark Research, “its body cavity is elongate and packed with a huge liver perfused with low-density oils and hydrocarbons, making the shark almost neutrally buoyant at depth.”

5. … AND IT MAY STRIKE AT ITS PREY LIKE A SNAKE.

No one has ever observed the frilled shark hunting, but scientists believe that it uses its posterior fins as propulsive surfaces to launch itself at its prey. Its long jaws, which terminate at the back of its head, may allow the animal to gape extra wide and take in prey half as long as its body. Analysis of the stomach contents of captured specimens has revealed that the frilled shark’s diet is 61 percent cephalopod, 11 percent teleost fishes, and, occasionally, other sharks.

6. IT’S FOUND ALL OVER THE WORLD—BUT YOU PROBABLY WON’T SEE IT.

The Food and Agriculture Organization of the United Nations notes that the frilled shark is “wide-ranging but spottily distributed”; you can see where the shark is found on the map above. It typically resides in depths between 390 and 4200 feet, so people rarely see these sharks unless they venture to the surface, which isn’t unheard of (as you’ll see below).

7. FEMALES ARE BIGGER THAN MALES.

On average, males range from 3.2 to 3.6 feet and females from 4.4 to 4.9 feet; the maximum these sharks can reach is 6.4 feet.

8. THEIR GESTATION PERIOD MAY BE 3.5 YEARS LONG.

A study of frilled sharks in Japan revealed that the animals breed year-round; litters typically consist of six pups, which emerge from eggs while still in the mother’s uterus and are then born live. Scientists think the shark may have the longest gestation period ever: Frilled sharks could gestate for as long as 42 months, nearly twice as long as African elephants carry their young. Scientists theorize that the extreme length has something to do with the shark’s cold deep sea habitat.

9. IT WASN’T SEEN IN ITS NATURAL HABITAT UNTIL 2004.

NOAA scientists exploring the “Latitude 31-30 Transect” in the Atlantic Ocean captured a video of a frilled shark “swimming over sea bottom that was covered with tiny sand dunes” during a submersible dive. “This species has been, on rare occasion, caught or taken in bottom trawls,” the site notes. “To the knowledge of everyone on board, however, this was the first time anyone had ever seen the rare species in its natural habitat.”

10. ONE WAS CAPTURED IN JAPAN IN 2007.

In January 2007, a Japanese fisherman spotted a strange, eel-like creature with a mouth full of sharp teeth near the surface; he alerted the staff of the Awashima Marine Park in Shizuoka, who captured the animal and transferred it to a seawater pool, where they filmed it. “We think it may have come close to the surface because it was sick, or else it was weakened because it was in shallow waters,” a park official said. “We believe moving pictures of a live specimen are extremely rare. They live between 600 and 1000 meters under the water, which is deeper than humans can go.” The shark, a female, died a few hours after its capture.

11. IT CALLS ANOTHER FREAKY SHARK ITS COUSIN.

The frilled shark might have rows upon rows of gnarly teeth, but its cousin, the goblin shark, can thrust its jaw out of its face. Which is more terrifying?

New Study Reveals 'Hyper-Alarming' Decline of Rainforest Insect Populations

iStock/jmmf
iStock/jmmf

Climate change is decimating yet another vital part of the world's ecosystem, according to a startling new paper. Rainforest insects are dying off at alarming rates, according to a new study spotted by the The Washington Post. In turn, the animals that feed off those insects are decreasing, too.

In the study, published in Proceedings of the National Academy of Sciences, a pair of scientists from the Rensselaer Polytechnic University in New York and the National Autonomous University of Mexico studied populations of rainforest arthropods (an invertebrate classification that includes insects and spiders) in the El Yunque National Forest in Puerto Rico. They compared the number of insects lead author Bradford Lister found on trips in 1976 and 1977 with the number he and co-author Andres Garcia found on trips they took between 2011 and 2013.

Lister and Garcia used nets and sticky traps to collect insects on the ground and several feet above the ground in the forest canopy. They dried these captured bugs and measured the mass of their haul against the mass of insects found in the 1970s, finding that the modern net sweeps captured only an eighth to a fourth of the insects captured in the '70s. The mass of insects captured by sticky traps on the ground declined by 30 to 60 times what they were a few decades ago. They also tracked populations of lizards, frogs, and birds that live off those rainforest insects, finding that those populations had declined significantly, too, at levels not seen in other rainforest animals that don't rely on insects for food.

Tropical insects are particularly vulnerable to climatic changes, since they can't regulate their body temperature. During the time of the study, average maximum temperatures in El Yunque rose by almost 4°F (2°C). The warming climate is "the major driver" of this decline in arthropod populations, the study authors write, triggering a collapse of the forest food chain.

The paper has other scientists worried. "This is one of the most disturbing articles I have ever read," University of Connecticut entomologist David Wagner, who wasn't involved in the research, told The Washington Post, calling the results "hyper-alarming." Other studies of insect populations have found similarly dire results, including significant declines in butterflies, moths, bees, and other species. One recent study found that Germany's flying insect populations had decreased by as much as 75 percent in the last three decades. Scientists don't always attribute those population losses directly to warmer temperatures (habitat loss, pesticide use, droughts, and other factors might play a role), but it’s clear that insect populations are facing grave threats from the modern world.

Not all insect species will be equally affected by climate change, though. While we may see a sharp drop in the populations of tropical insects, scientists project that the number of insects in other regions will rise—leading to a sharp increase in crop-eating pests in some parts of the world and broadening mosquitos' geographical range.

[h/t The Washington Post]

13 Chill Facts About Sloths

iStock.com/janossygergely
iStock.com/janossygergely

Sloths seem to be everyone's "spirit animal." They get to eat, sleep, and hang out in trees all day, going about their business without a care in the world. Or at least that's how it looks. As it turns out, there are plenty of good reasons why sloths are so sluggish—and laziness isn't one of them. Here are 13 things you should know about the world's slowest animal.

1. TWO-TOED AND THREE-TOED SLOTHS AREN'T ALL THAT SIMILAR.

A baby two-toed sloth
iStock.com/wekeli

The cute little babe pictured above is a two-toed sloth, of which there are two species belonging to the Megalonychidae family. The four species of three-toed sloths, on the other hand, are part of the Bradypodidae family. The two groups are only distant relatives and have a few notable differences between them. While three-toed sloths are active in the daytime, two-toed sloths are nocturnal creatures. Three-toed sloths are also smaller and slower than their two-toed counterparts.

2. BOTH HAVE THREE TOES, THOUGH.

A two-toed sloth
Tim Evanson, Flickr // CC BY-SA 2.0

The names used to distinguish the sloths are somewhat of a misnomer. Both have three toes on each hind limb. The real difference applies to the fingers on their forelimbs; one family has two claws, while the other has three. To avoid confusion, some groups—like The Sloth Conservation Foundation—have starting calling them two-fingered and three-fingered sloths.

3. THEY'RE RELATED TO THE EXTINCT GIANT GROUND SLOTH.

Illustration of a giant sloth
iStock.com/estt

Two-toed and three-toed sloths both evolved from giant ground sloths, the largest of which weighed several tons and stood about 12 feet tall. The animals went extinct about 10,000 years ago, likely due to hunting by early humans.

4. THEY WOULD FAIL AN EYE EXAM.

Close-up of a sloth
iStock.com/BrianLasenby

Sloths aren't exactly known for their sharp senses, and this is especially true for their eyesight. A mama three-toed sloth can't spot her own baby from 5 feet away, and combative male sloths have been observed trying to hit each other from a similar distance. Scientists say a genetic mutation is to blame. Three-toed sloths are born without cone cells in their eyes, which are needed to detect colors. As a result, they see things in black and white, and in poorer resolution, too. They also have a hard time handling bright lights—not the best trait for a diurnal (daytime) creature to have.

5. THEY'RE SURPRISINGLY GOOD SWIMMERS.

Sloths are painfully sluggish on land. Their hind legs are weak, so they have to use their arms and upper body strength to pull themselves forward. Plop them in some water, though, and they can move three times as fast. Their long front arms make them skillful swimmers, and they can hold their breath underwater for up to 40 minutes. If a body of water is nearby, they may jump in and use it as a shortcut to navigate the forest more quickly. In the above clip narrated by David Attenborough, a male sloth swims as fast as he can—which is pretty fast, all things considered—to track down a female sloth's mating call.

6. THEIR "LAZINESS" IS A SURVIVAL TACTIC.

A sloth in a chair
iStock.com/GeorgePeters

It's no secret that sloths are slow. Their reaction time is about a quarter as fast as a human's, and they move at a pace of 6 to 8 feet per minute. Indeed, three-toed sloths are the slowest animals on Earth, beating out other famously slow animals like giant tortoises and snails. When the animals were first documented in 18th-century scientific texts, they were harshly described as "the lowest form of existence." But their slowness is why they haven't died out. Sloths largely subsist on leaves, and it can take up to a month for their four-part stomachs to digest a single meal. The leafy greens aren't very nutritious, so they have to conserve as much energy as possible to survive—and that means moving less. As a bonus, their slow movements help them go unnoticed by predators that rely on sight to hunt down prey, like jaguars, ocelots, and harpy eagles.

7. THEY DO JUST ABOUT EVERYTHING IN TREES …

A baby sloth hangs from a branch
iStock.com/Mark Kostich

Sloths are arboreal creatures, so they spend almost all of their time in trees. They eat, sleep, mate, and give birth while hanging upside-down—a feat made possible by their anatomy. Their internal organs are anchored to their abdomen, which shifts weight away from their diaphragm and lets them breathe more easily, and therefore expend less energy.

Three-inch claws also help them latch onto branches and stay suspended far above the forest floor. In fact, their innate ability to cling to branches is so strong that dead sloths have been found dangling from trees, lending new meaning to the phrase "death grip."

8. … EXCEPT POOP.

A sloth on the ground
iStock.com/Damocean

As a consequence of their slow metabolisms, sloths poop once a week—and sometimes just once a month. Two-toed sloths often let 'er rip from the trees, but three-toed sloths follow a bizarre routine that has baffled scientists. They typically make their way down to the forest floor to relieve their backed-up bowels, and once they get there, they do a little "poo dance" while digging a small hole to defecate inside. Without the camouflage afforded to them by the foliage of the forest canopy, sloths are much more likely to be picked off by predators. About half of all sloth fatalities occur when they're on the ground, most likely doing their business or finishing up. So why do they do it? It might have something to do with sex, and marking a tree for a potential mate to find. "Whatever is going on, it's got to be kind of life or death for survival," sloth biologist Rebecca Cliffe tells The Washington Post. "In my brain, that tells me that it's probably something to do with reproduction because that is the driving fact behind most animals' crazy behaviors."

9. AND THEIR POOPS ARE ENORMOUS.

A man holds a sloth
iStock.com/Ssviluppo

When they do poop, their turds tend to be massive. If you put the contents of a sloth's bowel movement on a scale, they might weigh up to one-third of the animal's body weight. This is 282 percent larger than what scientists would expect to see in an animal of the sloth's size. "You can watch their stomachs physically shrink as they poo," Cliffe tells The Washington Post. Oddly enough, though, sloths don't fart. So there's that.

10. ALGAE OFTEN GROWS ON THEIR FUR.

A sloth covered in algae
iStock.com/dene398

Sloths have a symbiotic relationship with algae. Studies have shown that algae is sometimes passed down from a mother sloth to her baby, and the transfer is mutually beneficial for both animal and plant. The sloth's long fur creates a cozy home for the algae—which readily absorbs the water they need to thrive—and the sloths get a coat of green-tinted fur that doubles as camouflage. Sloths also eat the algae, which provides a much-needed source of nutrients.

11. FEMALE SLOTHS SCREAM WHEN THEY WANT TO MATE.

Females get the courting process started by letting out a loud, high-pitched scream to let male sloths know she's ready to mate. "This call is a loud 'eeeeeh' lasting more or less one second," sloth researcher Adriano Chiarello tells Live Science. Researchers are unsure on the particulars of sloth courting or copulation, or even if males will fight for the right mate with the screeching female (or if any fights are territorial instead). Whatever the details, the ensuing gestation period is between five and six months, and then the female sloth will birth one baby sloth, which is—uninterestingly—just called a baby sloth.

12. THREE-TOED SLOTHS CAN ROTATE THEIR HEADS 270 DEGREES.

A sloth turns its head to look back
iStock.com/MikeLane45

This special talent puts three-toed sloths in the same category as many owls. In both species, this Exorcist-esque ability can be attributed to their bone structure. Sloths have extra vertebrae at the base of their necks that let them look in all directions with ease. Although sloths aren't great at defending themselves, they can at least see when danger is approaching.

13. FOR SUCH DEFENSELESS CREATURES, THEY LIVE FAIRLY LONG LIVES.

A sloth peeks out from behind a tree
iStock.com/Damocean

"Live slow, die whenever"—the unofficial slogan bestowed upon sloths by the internet—pretty much gets it right. On average, sloths live to be about 20 years old, but some species can live longer in captivity. The world's oldest sloth—a female of the Hoffman's two-toed variety named Miss C—died last year at the ripe old age of 43. She was a lifetime resident of Australia's Adelaide Zoo.

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