The Pale-Throated Sloth: Species Facts & Characteristics

Pale-throated sloth in the rainforest. Photo by Steven Horvath.

The pale-throated sloth, or, by its more formal name, Bradypus tridactylus is a species of three-fingered sloths found in tropical rainforests of northern South America. Not to be confused with the more commonly found brown-throated sloth, the pale-throated sloth is aptly named for the pale-yellow patch of fur on its throat. Read on for more fascinating facts about this curious creature. 

How to Spot One

As with all three-fingered sloths, the pale-throated sloth has a small, rounded head and dark coloring around the eyes — often resembling a super-hero eye mask. They have very short, stubby tails, and the external portion of their ears is barely visible. Despite their tiny ears, however, sloths are known to have very good hearing!

Three-fingered sloths have long, coarse hair covering their bodies and, of course, three elongated claws (or “fingers”) at the end of each limb. Their hair grows so that it hangs down while the sloths are upside-down (their most common position), and this neat adaptation allows rainwater to flow away from their body and keep them drier during the rainy season!

Fun Facts

The pale-throated sloth has nine neck vertebrae (most mammals have seven). This unique feature allows sloths the flexibility to turn their heads 270 degrees! This saves them the energy of turning their full bodies when scanning for predators and means they can see everything “right side up” even if they're hanging upside-down from a tree! Even better than having eyes at the back of your head. 

Speaking of eyes, Bradypus tridactylus do not have cone cells in their retinas, which leads scientists to believe they see only in black and white

Sloths are sometimes seen to have a greenish looking appearance, which allows them to blend into the forest canopy. But this clever camouflage isn't actually their hair — it's a happy coincidence of the small green algae and fungi that commonly live symbiotically in the pits of their hair. These algae provide food to the many moths,and beetles sloths are also known to host in their hair — over 900 can live on one sloth at a time, and they don't seem to bother one another. 

Are They Actually Lazy?

It's true that sloths sleep for over eighteen hours a day and spend almost all of their time in the trees. They can even sleep upside down while hanging by their super-strong claws! On the rare occasion they do come down to the ground, they drag themselves around by their hands. Pale-throated sloths can stand on their feet but can't walk on them. Their limbs are long and very weak, and they typically move very slowly, even in the trees.

Pale-throated sloths move especially slowly on the ground, but wait until you get them in the water! Sloths are actually fairly good swimmers and can swim three times faster than they can move on land. 

What's for Dinner?

Bradypus tridactylus are herbivores and subsist entirely on twigs, leaves, and buds of cecropia and other rainforest trees. In part because of their very limited diet, sloths don't live well in captivity, where it's challenging to provide for their very specific diet. Their entire way of life is dependent on the rainforest trees. 

Sloths are believed to have one of the slowest metabolisms of any non-hibernating mammal, and it can take them almost a monthto digest one single leaf. Speaking of a full stomach…

Potty Talk

Not to get gross, but in the name of science, we HAVE to tell you something about the pale-throated sloth's bathroom habits. These mammals are famous for relieving themselves only once per week — sometimes losing up to a third of their body weight in one toilet trip. Talk about holding it in! 

Baby Makes Three

Pale-throated sloths gestate for five to six months and give birth to one offspring at a time, most often in March or April, which is the start of the rainforest's dry season. After birth, the babies cling to their mothers' bellies for about a month. The mothers provide their young milk and leaf samples from around one-week-old. The fathers are not involved in caring for offspring, so it's all up to the mother. Luckily, pale-throated sloths are considered mature at three years old, so the mothers don't have too long to toil as a single parent.  


While pale-throated sloths are not currently endangered, they are seriously impacted by the deforestation of rainforests. They rely entirely on tree canopy for food, shelter, and protection from predators. What's more, Bradypus tridactylus have traditionally fared very poorly in captivity and, therefore, would be unlikely to fare well in captive conservation settings. 

These amazing mammals are just one more reason to take care of our earth and save the rainforests!