Searching for Sloths

Splash! A pygmy sloth drops out of a red mangrove tree, falling into the crystal-blue water. It starts swimming by leisurely paddling its long arms. Minutes later, the sloth reaches a nearby tree root. It slowly pulls itself up. Then the sloth begins its slow climb up to the top branches of the tree in search of its next meal.

All sloths can swim. But off the coast of Panama lives the only sloth known to swim in salt water—the pygmy sloth. Pygmy sloths are the most recently identified species of sloth. No one is sure how many there are, but there aren’t a lot. Because they are so rare, scientists didn’t determine they were a distinct species until 2001!  

Splash! A pygmy sloth drops out of a red mangrove tree. It falls into the clear blue water. It slowly paddles its long arms to start swimming. Minutes later, the sloth reaches a nearby tree root. It carefully pulls itself up. Then the sloth begins its slow climb up to the top branches of the tree. It's on its way to find its next meal.

All sloths can swim. But pygmy sloths are the only sloths known to swim in salt water. The small sloths live off the coast of Panama. No one is sure how many of them there are. But scientists know that there aren't many. Because pygmy sloths are so rare, scientists didn't even know they were their own species until 2001!

Adults weigh about 6 pounds and are the size of a skunk. Pygmy sloths live on a small island, about 10 miles off the coast of Panama. Smaller-than-average brown-throated sloths live on some of the nearby islands. So for a long time when scientists came across a pygmy sloth, they thought it was a young brown-throated sloth.

Like other sloths, pygmy sloths are not known for their speed on land. On average, sloths travel at most 120 feet per day. In the water, however, these Muppet-like mammals can swim at speeds about three times their pace on land. “I was impressed by how capable and graceful they were in the water!” says Becky Cliffe. Cliffe, a zoologist from the United Kingdom, has spent the past five years researching sloths. It takes a lot of patience and hard work to study these slow-moving creatures.

Adult pygmy sloths are the size of a skunk. They weigh about 6 pounds. They live on a small island, about 10 miles off the coast of Panama. Slightly larger animals called brown-throated sloths live on nearby islands. So scientists who came across pygmy sloths used to mistake them for young brown-throated sloths.

Sloths are not known for their speed on land. They usually travel no more than 120 feet per day. In the water, however, sloths move more quickly. The Muppet-like mammals can swim about three times faster than they crawl. "I was impressed by how capable and graceful they were in the water!" says Becky Cliffe. Cliffe is a zoologist from the United Kingdom. She has spent the past five years studying sloths. It takes a lot of patience and hard work to study these slow-moving creatures. 

Sloths live in the rainforests of Central and South America. They have long arms like monkeys but are actually related to anteaters. There are six species of sloths, which fall into two categories: three-toed sloths and two-toed sloths. They spend nearly all their time hanging from the upper branches of the highest trees in the rainforest, known as the canopy. They move so slowly that algae grow on their fur.

Sloths aren’t slow just when it comes to moving. It can take a whole month for a sloth to digest a single leaf. But this laid-back pace can be a lifesaver. Sloths often eat leaves that are toxic. If they were to digest the leaves too quickly, the sloths could be poisoned. Because it takes such a long time to break down dinner, a sloth can spend more than half its day resting as it digests.  

Sloths live in the rainforests of Central and South America. Their long arms make them look like monkeys. But they're actually related to anteaters. There are six species of sloths in all. They fall into two categories: three-toed sloths and two-toed sloths. Both spend nearly all their time hanging in trees. They prefer the canopy, or the upper branches of the highest trees in the rainforest. They move so slowly that algae grow on their fur.

Sloths aren't only slow when it comes to moving. It can take a whole month for a sloth to digest a single leaf. But this laid-back pace can be a lifesaver. Sloths often eat leaves that are toxic to other animals. Because sloths digest the leaves so slowly, the leaves don't poison them. Digesting slowly has another advantage. A sloth can spend more than half its day resting as its meals break down. 

Sloths are masters of camouflage. They sleep and keep still during the day. The green algae in their fur helps them blend into the forest canopy they call home. Spotting a sloth in the wild is tough work, but the rainforest itself also poses its own challenges to scientists studying them.

“It’s full of snakes, spiders, scorpions, bullet ants, and hairy caterpillars, just to name a few! All of which can cause some serious problems,” says Cliffe. 

The challenges of observing sloths is one of the reasons we know so little about them. But Cliffe is working to change that. Her research has shed some light on the lives of sloths (see Sloth Backpack Project). “It is only in recent years that we are beginning to see just how the sloth lifestyle is an incredibly successful survival strategy,” says Cliffe. “They are stealthy rather than lazy.”

Sloths are also masters of camouflage. They sleep and keep still during the day. The green algae in their fur helps them blend into the forest canopy. It also makes spotting a sloth in the wild tough work. But scientists studying sloths face bigger challenges in the rainforest.

"It's full of snakes, spiders, scorpions, bullet ants, and hairy caterpillars, just to name a few!" says Cliffe.

Because it's so hard to observe sloths, scientists don't know much about them. But Cliffe is working to change that. Her research has shed some light on the lives of sloths. "We are beginning to see just how the sloth lifestyle is an incredibly successful survival strategy," says Cliffe. "They are stealthy rather than lazy." 

Pygmy sloths’ habitat is threatened. The trees they live in are being cut down to make space for farms, roads, and houses. At least 1 acre of rainforest is cleared every second. Given sloths’ slow lifestyle and specialized diet, they don’t adapt well to rapid changes in their environment.

Although the pygmy sloth is the most endangered sloth species, it’s not the only sloth species that’s in trouble. The maned sloths of Brazil are also listed as vulnerable. “From power line electrocutions and dog attacks to road collisions, deforestation, and human cruelty—it is a long and sad list of threats,” says Cliffe. 

Rainforest destruction threatens many other plants and animals too. Cliffe says even little actions, like supporting local farmers and eating less meat, can help save the rainforest. These changes reduce the need to cut down the rainforest for farmland and livestock grazing.

For Cliffe, the challenges of her slow-paced research are worth it. “Working hands-on with sloths is truly magical,” she says. “I have a real opportunity to learn more about these unusual animals and use the information to make a positive difference.”

Pygmy sloths' habitat is threatened. The trees they live in are being cut down to make space for farms, roads, and houses. At least 1 acre of rainforest is cleared every second. Sloths don't adapt well to these quick changes in their environment.

The pygmy sloth is the most endangered sloth species. But it's not the only sloth species that's in trouble. The maned sloths of Brazil are also considered vulnerable. "From power line electrocutions and dog attacks to road collisions, deforestation, and human cruelty, it is a long and sad list of threats," says Cliffe.

A shrinking rainforest threatens many plants and animals. But Cliffe says even little actions can help save the trees. If people eat less meat, fewer trees will be cut down to make fields for livestock. Buying from local farmers instead of faraway ones makes a difference too.

For Cliffe, the slow and challenging research is worth it. "Working hands-on with sloths is truly magical," she says. "I have a real opportunity to learn more about these unusual animals and use the information to make a positive difference."