sloth, arboreal mammal found in Central and South America distantly related to armadillos and anteaters. Sloths live in tropical forests, where they sleep, eat, and travel through the trees suspended upside down, clinging to branches with the powerful curved claws of their forelimbs and hindlimbs. Algae that grow on the hair impart a greenish color to the coat so that it blends with the foliage. There is no tail. The three-toed sloth (Bradypus) is about the size of a house cat, with a dense, furry coat and yellowish face. It has three toes on the front feet and five on the hind feet. It feeds almost exclusively on the leaves, buds, and stems of Cecropia, a tropical relative of the mulberry. The somewhat larger two-toed sloth (Choloepus) has very long hair. It eats a less restricted vegetarian diet. Sloths move sluggishly but can strike swiftly and powerfully if attacked. Huge ground sloths (see megatherium) are extinct forms. Sloths are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Edentata, family Bradypodidae.

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.

Learn more about sloth with a free trial on Britannica.com.