What Do Sloths Eat? Leaves, Fruit and Very Slow Digestion

What three-toed sloths eat

Three-toed sloths, such as the brown-throated sloth, are true leaf-eaters, or folivores. Almost everything they eat is foliage: young leaves, leaf buds and shoots, plus some flowers and a little fruit.

Each individual sloth seems to have its own short list of favorite trees. A baby feeds alongside its mother for months and learns to use the same trees she does, so food preferences are passed down from mother to young. That is one reason three-toed sloths do so poorly when moved to unfamiliar places or zoos.

Cecropia trees, with their large, umbrella-like leaves, are famous as “sloth trees”. Sloths do eat their leaves, but the trees’ open crowns also make sloths easy to spot, so photos give an exaggerated picture. Field studies show three-toed sloths feeding on many other trees and vines as well.

What two-toed sloths eat

Two-toed sloths, such as Hoffmann’s two-toed sloth, are less picky. They eat leaves too, but also more fruit, flowers, buds, shoots and tender twigs. They have been seen at mineral licks, where they probably pick up salts and minerals missing from their diet.

There are also reports of two-toed sloths eating insects, eggs or other small animal food, which is why some sources call them omnivores. Most of these accounts are occasional observations, and plants make up nearly all of their diet. Two-toed sloths also have sharp, canine-like front teeth, while three-toed sloths have only simple peg-like teeth.

How do sloths digest leaves?

Leaves are a poor food. They are full of tough fiber and often contain chemical defenses, and they provide little energy. Sloths solve this problem by digesting very slowly.

A sloth has a large stomach divided into several chambers. Inside, bacteria and other microbes break down the fiber by fermentation, a bit like the process in a cow’s stomach. The sloth then absorbs the products of that fermentation as energy.

This is a slow process. In three-toed sloths, food can take a week or more to pass through the gut, and some estimates suggest up to about a month for a single meal. A large share of a well-fed sloth’s body weight, by some estimates up to around two-thirds, is the contents of its digestive system.

Temperature matters too. Sloths cannot keep their body temperature as steady as most mammals, and when the weather is cool their gut microbes work more slowly. On cold days, sloths eat less and digestion slows down even more.

How much do sloths eat?

Not much. Because their metabolism runs at roughly half the rate expected for a mammal of their size, sloths need far less food than a monkey or squirrel of similar weight. They spend long periods resting between short bouts of feeding, plucking leaves with their tough lips rather than their hands.

This low-energy lifestyle is the main reason sloths are so slow. Moving fast would burn energy that a leaf diet cannot supply. See why are sloths so slow? for the full explanation.

Do sloths drink water?

Sloths rarely need to drink. Fresh leaves are mostly water, and sloths probably also take in dew and rainwater on the leaves they eat. They have occasionally been seen drinking from rivers and streams, especially in dry periods.

The weekly bathroom trip

Slow digestion also explains one of the strangest sloth habits. Rather than relieving themselves from the treetops, sloths climb down to the ground about once a week, dig a small hollow at the base of a tree and leave their droppings there. It is a risky trip, and scientists still debate why they do it. Read more in how often do sloths poop?.

Myths and facts

• Myth: sloths eat only Cecropia leaves. Fact: they use many kinds of trees and vines.
• Myth: sloths eat bugs that live in their fur. Fact: there is no good evidence for this. Some researchers think sloths may eat a little of the algae in their fur, but that is still a hypothesis.
• Myth: sloths are slow because they are lazy. Fact: slowness is an energy-saving adaptation to a diet that provides very little fuel.

Both of these sloths are classed as Least Concern by the IUCN, but they depend on healthy, connected forest canopies to find the leaves they need.