Sloth

The sloth is a South American mammal which spends most of its life hanging upside down in trees, relying on obscurity through immobility, camouflage, and being unreachable for protection against predators.

The camouflage is provided by symbiotic blue-green algae growing in their "wrong way" fur, which has outer hairs pointing upwards, so the fur hangs down when sloths are hanging from the tree. They don't fall off while sleeping because their muscles become fixed when they fall asleep, rather than relaxing as with most other mammals.

Sloths are herbivores, eating leaves and fresh twigs.

Order: Xenarthra, suborder Pilosa[?]

Family: Bradypodidae[?]

Those with three toes on their front feet belong to the genera Bradypus[?] and Arctopithecus[?], the best known being the collared sloth (Bradypus tridactylus) and the Ai (Arctopithecus ai)

Family: Megalonychidae[?]/Choloepidae[?].

Those with two toes on their front feet belong to the genus Choloepus[?] of which the best known is the unau (Choloepus didactylus).

Sloths move more slowly than most other animals, which protects them from being noticed by carnivores: most hunters notice movement better than shape.

Infant sloths normally cling to their mother's fur; those that fall off have been known to die, because the mothers are sometimes unwilling to leave the safety of the tree to retrieve them.

Despite their adaptation to living in trees, sloths have been found to be able swimmers.

Until very recently large ground-dwelling sloths, Megatherium, could be found in North America. These died out before the arrival of Europeans on that continent, but after the first human settlement: as with other extinct North American megafauna, there is debate over whether humans caused, or contributed to, their extinction.

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The name "sloth" has also been given to other animals, usually slow ones, including the sloth-bear[?] of India, and several primates or "sloth monkeys", including species of slow loris, lemur and galago. The koala has been called the "Australian sloth" from its habit of hanging upside down.

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All these animals are named from noun sloth, which is simply the Middle English noun-form of the adjective slow (formed in the same way as true→truth). In modern usage, however, it means "lazy, inactive, idle, indolent, sluggish, and slow"; these bad qualities make Sloth one of the Seven deadly sins.