THE SLOTH

Sloths are medium-sized mammals belonging to the families Megalonychidae (two-toed sloth) and Bradypodidae (three-toed sloth), classified into six species. Extant sloths are arboreal (tree-dwelling) residents of the jungles of Central and South America, and are known for being slow-moving and hence named "sloths". Extinct sloth species include a few species of aquatic sloths and many ground sloths. Sloths are classified as folivores, as the bulk of their diets consist of buds, tender shoots, and leaves, mainly of Cecropia trees. Some two-toed sloths have been documented as eating insects, small reptiles, and birds as a small supplement to their diets. Linnaeus's two-toed sloth has recently been documented eating human faeces from open latrines. They have made extraordinary adaptations to an arboreal browsing lifestyle. Leaves, their main food source, provide very little energy or nutrients, and do not digest easily. Sloths, therefore, have large, specialized, slow-acting stomachs with multiple compartments in which symbiotic bacteria break down the tough leaves. Sloths' tongues have the unique ability to protrude from their mouths 10 to 12 inches, an ability that is useful for collecting leaves just out of reach. As much as two-thirds of a well-fed sloth's body weight consists of the contents of its stomach, and the digestive process can take a month or more to complete.

Sloths make a good habitat for other organisms, and a single sloth may be home to moths, beetles, cockroaches, ciliates, fungi, and algae. Although unable to survive outside the tropical rainforests of South and Central America, within that environment sloths are outstandingly successful creatures. Sloths' claws serve as their only natural defense. A cornered sloth may swipe at its attackers in an effort to scare them away or wound them. Despite sloths' apparent defenselessness, predators do not pose special problems: sloths blend in with the trees and, moving only slowly, do not attract attention. Only during their infrequent visits to ground level do they become vulnerable. The main predators of sloths are the jaguar, the harpy eagle, and humans. The majority of recorded sloth deaths in Costa Rica are due to contact with electrical lines and poachers. Their claws also provide a further unexpected deterrent to human hunters; when hanging upside-down in a tree, they are held in place by the claws themselves and often do not fall down even if shot from below.