The sloth, from the South American rainforest, spends most of its life hanging upside down in trees. It is a nocturnal animal, with long legs, a flat face and long, curved claws. They move so slowly that they may only travel a few metres each day. There are four species of three-toed sloth and two of two-toed sloth. Two-toed sloths eat insects, carrion, fruits, leaves and small lizards. Three-toed sloths eat only leaves. Sloths are xenarthrans, a group of mammals that also includes armadillos and anteaters.

Sloths spend so much of their lives in the trees that they are unable to walk normally on the ground. Instead, they hang upside down from the branches using their curved, hook-like claws to grip on without effort. They eat, mate and give birth hanging upside down. Even their fur grows downwards from their stomachs, so that the rain runs off it. Tiny, plant-like algae grow on their coats, giving sloths a greenish tinge. This helps camouflage them from jaguars and harpy eagles.