SLOTH, the name for the various representatives of a group of arboreal tropical American mammals belonging to the order Edentata (q.v.). Sloths are some of the most completely arboreal of all mammals, living entirely among the branches of trees; and usually hanging beneath them, back downwards, and clinging with the hook-line organs to which the terminations of their limbs are reduced. When obliged to descend to the ground, which they rarely, if ever, do voluntarily, sloths—owing to the unequal length of their limbs and the peculiar conformation of their feet, which allow the animals to rest only on the outer edge—crawl along a level surface with considerable difficulty. Though generally slow and inactive, even when in their natural haunts, they can on occasions travel with considerable rapidity along the branches, and as they do not leap, like most other arboreal creatures, they avail themselves of the swaying of the boughs by the wind to pass from tree to tree. They feed on leaves and young shoots and fruits, which they gather in their mouth, the fore-limbs aiding in dragging boughs within reach, but not being used as hands. When sleeping, sloths roll themselves up in a ball, and, owing to the dry shaggy character of their hair, are inconspicuous among the mosses and lichens with which the trees of their native forests abound. The concealment thus afforded is heightened in some species by the peculiar greenish tint of the hair, due not to the colour of the hair itself, but to the presence upon its surface of an alga, the lodgment of which is facilitated by the fluted or rough surface of the exterior, and its growth is promoted by the dampness of the atmosphere in the gloomy tropical forests. Sloths are
The Unau or Two-toed Sloth (Choloepus hoffmanni).
nocturnal, silent, inoffensive and solitary animals, and produce usually but one young at birth. They appear to show an almost reptilian tenacity of life, surviving the most severe injuries and large doses of poisons, and exhibiting longer persistence of irritability of muscular tissue after death than other mammals. Several other animals, such as the African potto-lemurs, and the Asiatic lorises, are popularly called sloths.