Sloths eat leaves with very little nutritional value; in fact, it takes up to a month for their food to digest. They eat just enough to store energy for the limited movements they make, but otherwise, there isn’t much leftover for other activities.
To compensate, they have a metabolic rate about half that of other mammals their size. Since they can’t run away from predators or fight them off easily, they hide instead.
Hanging below branches makes them less visible to harpy eagles and their claws can grip the branch without using any energy – indeed, sloths won’t fall from a tree even if they’re shot! Their long claws can be up to 10 centimetres long (4 inches), making them the perfect tool for hanging safely onto branches. These long claws make walking on the ground extremely difficult; so they’re perfectly adapted to a life in the trees.
Staying hidden this way gives sloths a great advantage. Interestingly, they move so slow it gives algae time to grow on the animal’s fur. This is what is known as a mutualism. The algae gets a warm place to grow, and in return, the sloth gets extra green moss-like camouflage to help it stay hidden amongst the leaves from predators.
Sloths spend so much time upside down that their fur lies the opposite way to most mammals, growing from the paws up to the body. Although it seems they spend their whole lives upside down, sloths actually spend 90 per cent of their lives upside down, and return to the forest floor once a week to ‘use the toilet’.