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(vertebrate zoology)
A family of mammals in the order Edentata comprising the true sloths.



(sloths), a family of mammals of the order Edentata. Body length, 50–64 cm; weight, 4–7 kg. The front legs are longer than the hind legs; the toes (there are two-toed and three-toed sloths) have powerful sickle-shaped claws; the neck is very mobile, allowing the head to turn as much as 270°. Bradypodidae have 18 teeth. Unlike other mammals, they have six to nine cervical vertebrae and 14–24 pairs of ribs. The long hair is grayish brown and often has a greenish tinge caused by the algae that grow in it. The senses of sight and smell are well developed in sloths, but their sense of hearing is not as acute. Body temperature is changeable, varying from 24° to 35°C.

There are two genera, Bradypus and Choloepus, with seven species distributed in South and Central America. They inhabit tropical forests, living in treetops. Nocturnal mammals, sloths sleep during the day, curled up in the vertical crotches of trees. They move extremely slowly and are not mobile. They usually hang horizontally from branches with their backs to the ground; they come down only when it is necessary and will crawl across open spaces as far as 30–40 m. Sloths may spend their entire lives in the top of one tree. They live alone or in pairs (rarely); the single young is born once a year. Sloths eat leaves, young shoots, and fruit.


Zhizn’ zhivotnykh, vol. 6. Moscow, 1971.