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.

A Newly Discovered Species of Prehistoric Shark Was Named After the Video Game Galaga

Velizar Simeonovski, Field Museum
Velizar Simeonovski, Field Museum

Dinosaurs weren’t the only fearsome creatures who called North America their home millions of years ago. The recent discovery of pointy, fossilized teeth in rock that had been left over from an excavation in the ‘90s has led scientists to declare a new—yet long-extinct—shark species, Smithsonian reports.

North Carolina State University professor Terry Gates, who led the study published in the Journal of Paleontology, named the shark species Galagadon nordquistae after its triangular teeth, which he thought resembled the shape of the battleships in the video game Galaga. The second part of the name pays homage to Karen Nordquist, the retired chemist and volunteer at Chicago’s Field Museum who found the fossils in the first place.

Galagadon lived in what we now know as South Dakota’s Hell Creek Formation, an area known for having rocks and fossils that date back at least 65 million years to the Cretaceous Period. It’s the same place where scientists unearthed Sue the T.rex—the most complete skeleton of its species ever discovered. Not only did the shark live at the same time as Sue, but it also “lived in a river Sue probably drank from,” the Field Museum, where Sue can be seen on display, said in a press release.

In fact, the excavation that led to Sue’s discovery in 1990 is what enabled this latest find. The sediment that encased Sue’s bones, known as matrix, was removed and stored in an underground unit at the Field Museum. Scientists and museum volunteers have only recently begun to sift through it in search of smaller fossils.

Shark tooth fossils
Terry Gates, Journal of Paleontology

Sharks’ skeletons are primarily made of cartilage, which deteriorates over time. But the tiny teeth, measuring just a millimeter wide, helped scientists figure out what the shark looked like. "Galagadon was less than 2 feet long—it's not exactly Jaws," Pete Makovicky, one of the study’s authors, said in a statement.

The species is believed to be similar to bamboo sharks, which can be found today in southeast Asia and Australia. This connection surprised researchers, who are now questioning their understanding of the area where Sue was found, which was thought to be a lake formed from a partially dried-up river. This latest discovery, however, indicates that there “must have been at least some connection to marine environments," Makovicky says.

[h/t Smithsonian]

12 Animals Named After the Noises They Make

A bobolink, said to have been named for the call it makes
A bobolink, said to have been named for the call it makes
iStock.com/PaulReevesPhotography

If you were asked to name an onomatopoeic word, then you’d probably come up with something like boom, boing, whizz, smash, or tick-tock. They’re all perfectly good examples, of course, but onomatopoeia is actually responsible for a lot more words than you might think. For instance, etymologists believe that pebble might have been coined to imitate the sound of flowing water. Laugh might have been invented to sound like, well, a laugh. Owl, crow, and raven are all descended from Old English words (ule, crawe, hræfn) that were meant to imitate the owl’s hoot and the crow’s and raven’s squawks. And the 12 names listed here are all meant to represent the bizarre whoops, chips, peeps and wows made by the animals they describe.

1. AI

An ai in Venezuela
Fernando Flores, Wikimedia Commons // CC BY-SA 2.0

As well as being a contender for the world’s shortest animal name, ai (which should be pronounced “ah-ee") is another name for a three-toed sloth, especially the pale-throated sloth, found in the far northeast corner of South America. Although sloths are generally fairly docile, the name ai is apparently meant to resemble the high-pitched cry they can make when they’re agitated or alarmed.

2. BOBOLINK

Bobolinks can produce very long and surprisingly complex songs, but their usual go-to noise is a brief four-note call that’s commonly said to sound like someone saying “Bob-o-Lincoln.” The name Bob-o-Lincoln eventually was shortened to bobolink in the 1800s.

3. CHIPMUNK

One theory claims that the name chipmunk is an English interpretation of a native Ojibwe word, ajidamoo, meaning something like “red squirrel.” But because chipmunks were originally known as “chipping squirrels” in English, it seems more likely that the name is actually an English invention, in which case it’s probably meant to describe their short “chipping” call.

4. CHOWCHILLA

A chowchilla
Seabamirum, Flickr // CC BY 2.0

The chowchilla is type of logrunner, a small thrush-like bird, that’s native to Queensland, Australia. For a bird not much larger than a robin, the chowchilla has a particularly noisy call that to early European colonists and explorers apparently sounded like “chow-chilla-chow-chow.” The chowchilla was also once known as the “auctioneer bird,” apparently because (with a bit of imagination) its song sounds like an auctioneer's incessant chattering.

5. CHUCK-WILL’S-WIDOW

A cousin of the better-known whippoorwill, the chuck-will’s-widow is another species of nightjar (a family of nocturnal birds related to swifts and martins) native to the southern United States and much of Central America. Dozens of different species of nightjar are found all over the world, and they all share incredible camouflaged plumage and strange whooping calls—so if the “whippoorwill” makes a noise that sounds like poor Will is about to be whipped, then the “chuck-will’s-widow” makes a sound like poor Will’s widow is about to be chucked.

6. GANG-GANG

A gang-gang cockatoo
iStock.com/JohnCarnemolla

The peculiar croaking noise made by the gang-gang cockatoo of southeast Australia has been likened to everything from a creaking wooden door to a cork being pulled from a wine bottle. However you might want to describe it, the onomatopoeic name gang-gang was adopted into English from a Wiradhuri name that was supposed to imitate it.

7. HOOPOE

Hoopoe bird on a branch
iStock.com/shurub

The hoopoe is a striking-looking songbird whose name is meant to imitate its strange whooping call. Their bizarre appearance has also helped make them the frequent subject of myths and folktales over time: the Ancient Egyptians worshipped them and drew pictures of them inside the pyramids; the Romans believed that they were filthy creatures because they fed on dung and frequently nested in graveyards; and at least one old European legend claims that the younger birds look after the older ones in their old age, restoring their youth by plucking out dying feathers and licking blindness from their eyes.

8. KATYDID

A katydid on a purple flower
iStock.com/blindsquirrelphoto

Katydids make their loud and often three-syllable “ka-ty-did” call by rubbing their forewings together. They hear each other, incidentally, with ears located on their front legs. There are more than 6000 species in the katydid family, found on every continent except Antarctica.

9. MACAQUE

The name macaque was borrowed into English via French in the late 17th century, but it’s thought to originally derive from an old Bantu name, kaku, for any of the numerous monkey species found in West Africa. The name kaku is in turn supposed to be imitative of a monkey call, and it’s from the plural form of kaku—namely makaku in Bantu—that the word macaque eventually evolved.

10. PEEWIT

A type of plover with characteristic green plumage and a long curled crest, the northern lapwing has a number of nicknames in English—including the peewit, the swipe, the peepsweep, the teewhit, and the teeack—every one of which is supposed to emulate its noisy alarm call. The common name lapwing, incidentally, refers to the bird’s tactic of feigning a broken wing in order to distract predators from their nest when they feel threatened.

11. PIET-MY-VROU

Piet-my-vrou is another name for the red-chested cuckoo, a species of cuckoo found across much of sub-Saharan Africa. Cuckoos are well known for their instantly recognizable call, and it’s the loud three-note descending call of the piet-my-vrou (which literally means “Pete my wife” in Afrikaans) that gives it its name.

12. WOW-WOW

A wow-wow, or agile gibbon

Gibbons are famous for their lengthy and surprisingly complex songs, and the whooping or “wowing” call of the wow-wow or wawa—a local Indonesian name for either the agile gibbon or the silvery gibbon—is no exception. Sadly both species are now listed as endangered, due to their localized distribution and on-going habitat destruction.

This story first ran in 2014.

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