Nocturnal, solitary, tree-dwelling mammal (family Bradypodidae), found in South and Central America. About 2 ft (60 cm) long, sloths have a tiny tail, peglike teeth, long curved claws, and long forelimbs. A green alga grows in the shaggy fur. The four species of three-toed sloths, or ais (Bradypus), eat only leaves of the trumpet tree. The two species of two-toed sloths, or unaus (Choloepus), have two toes on the forelimbs; they eat fruits, stems, and leaves of various plants. Sloths cannot walk. They cling upright to trunks, hang upside down (in which position they sleep some 15 hours a day), or move, extremely slowly (hence their name), by pulling hand over hand. Their natural camouflage is their chief protection from predators.
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