The three-toed sloths are the only members of the Bradypus genus and the Bradypodidae family. There are four living species of three-toed sloths. These are the Brown-throated Sloth, the Maned Sloth, the Pale-throated Sloth, and the Pygmy Three-toed Sloth.
Although similar to the somewhat larger and generally faster moving two-toed sloths, the two genera are not particularly closely related. Both types of sloth tend to occupy the same forests: in most areas, a particular single species of three-toed sloth and a single species of the larger two-toed type will jointly predominate. Famously slow-moving, the sloth travels at a top speed of 0.15 mph. Although they are quite slow in trees, three-toed sloths are agile swimmers. The offspring cling to their mother's bellies for around 9 months or so. They cannot walk on all four, therefore, they must use their front arms and claws to drag themselves across the tropical rain forest floor. Scientists do not know exactly when these mammals mate, but it is estimated to be somewhere around March or February.
The three-toed sloth is almost totally arboreal ("tree-dwelling"), with a body "built to hang." It lives in the shrub or lower tree layer, but sometimes moves to the canopy. Its long, coarse, grayish-brown fur often appears greenish, not due to pigment but to algae growing on it. The sloth’s greenish color and its sluggish habits provide an effective camouflage: hanging quietly, the sloth resembles a bundle of leaves. Large curved claws help the sloth to keep a strong grip on tree branches.