Sloths are primarily folivores – meaning an animal who eats leaves. Wild sloths have sometimes been observed to eat fruit and seed pods from trees. Sloths in captivity are often fed fruits and vegetables, but it is not known if this is good for them.
Most animals don’t eat leaves because leaves have tough cellulose cell walls that are difficult to digest, have very few calories, and have a lot of toxins that can build up over time. Sloths combat this by mostly eating young leaves which contain lower levels of cellulose and toxins, and by rotating tree species in order to avoid a build-up of toxins.
Although sloths, in general, are known to feed from more than 90 different tree species, an individual sloth will rotate among approximately 7 to 12 favorite feeding trees – a strategy that prevents them from overeating any one kind of leaf.
Folivorous animals have the slowest metabolic rates in the land animal kingdom. Most folivores compensate for the low energy content of leaves by eating a large amount to make up for it: howler monkeys, which often share the same territories and even trees as sloths, eat 3 times as many leaves per kilogram of body weight as a sloth does!
Myth-busting – sloths make good neighbors to their fellow tree-dwelling animals and don’t eat birds or their eggs.
6.2 Sloths drink water
Sloths get most of the water they need from the foliage they consume, however both two-fingered and three-fingered sloths will drink from rivers, particularly on hot, dry days.
Two-fingered sloth will eat the soil and small stones from the forest floor. This is thought to help with digestion, provide extra salts and minerals and help neutralize toxins the sloth may have eaten.
Myth-busting – sloths don’t eat the algae and fungi growing on their fur!
Sloths need to stay warm to digest their food. If they get too cold, sloths can die of starvation even on a full stomach. This is because the bacteria which breaks down the leaves will die if a sloth’s body temperature falls too low, leaving undigested leaves in their stomach which are unable to pass along or be regurgitated.
If this happens, the only way to save these animals is to replenish the gut bacteria. This can be done by giving the sloth probiotics or (in extreme cases) fecal matter from a healthy sloth – something that rescue centers fondly refer to as a “poop cocktail”.
It takes a sloth 28 days to digest one leaf! As a result, they have a constantly full stomach (which can account for up to 30% of their body mass) and therefore can’t eat very much on a daily basis.
In a study conducted by Dr. Rebecca Cliffe, it was discovered that sloths increase their levels of food intake on hotter days when they are better able to metabolize it. This is in stark contrast to most other mammals which tend to eat more on colder days to help maintain their body temperature. Sloths really do seem to do everything backwards!
Myth-busting – the leaves sloths eat do not contain psychoactive substances which makes them slow.