The hair of Linne's two toed sloth is coarse and grooved. The grooves are filled with greenish algae, which helps conceal the animal in its forest home. Males and females are alike in appearance. Sloths have no canine teeth, but their first premolars have a sharp fang-like cusp that gives the appearance of canine teeth and enable the animal to inflict a serious wound. They are about 2 feet long and weigh 10-15 pounds. They have a very flexible neck that enables them to reach all around themselves without moving.
Sloths are the most spectacularly successful large mammals in Central and South America. In many places they account for one fourth to two-thirds of the total mammalian biomass and half of the energy consumption of all terrestrial mammals. This success is largely because the effects of competitors and predators are scarcely perceptible. They eat what very few other mammals want, and most predators do not detect them. The metabolic rate of sloths is slow -- about 40 to 45% of that of a comparably-sized terrestrial mammal.