By Sharon Jansa
Geographic Range
Restricted range in the remaining fragments of Brazilian coastal Atlantic rainforest.
Biogeographic Regions:
neotropical 
(native ).
Habitat
Once thought to inhabit a single tree, three-toed sloths are known to have home ranges as large as 16 acres and will travel from tree to tree using canopy lianas. They choose trees with exposed crowns and will thermoregulate by moving in and out of the sun.
Terrestrial Biomes:
forest ; rainforest .
Physical Description
Round head with a flat face and small, hidden ears. Simple, ever-growing teeth, 5 upper, 4 lower. Three long, strong claws on the hands. Fur coarse, long, shaggy, often tinged green with a blue-green algae. Head and body grizzled tan. The most noticable feature is the long, black mane on the shoulders and back of the neck. Measurements: Head-Body: 450-500mm; Tail: 48-50mm; Hind Foot: 100-115mm.
Some key physical features:
endothermic ; bilateral symmetry .
Reproduction
Females give birth to one young per year. Gestation lasts about six months; young nurse for six weeks, but are able to eat leaves at two weeks. Females carry the young for six months after which the young are abruptly left. Males and females reach sexual maturity in their third year.
Key reproductive features:
gonochoric/gonochoristic/dioecious (sexes separate); sexual .
Behavior
Sloths are solitary, tree-dwelling animals. The longest social bond formed is that between mother and young. Once they are weaned, young will inherit trees in the mother's home range. Reproductively active females have a two-part home range, one part is used for rearing young, the other is used while the female is pregnant and without dependent young.
Key behaviors:
motile .
Food Habits
Strictly folivorous. All sloths have long, multi-chambered stomachs filled with cellulose-digesting bacteria. This allows them to extract energy from nutrition-poor mature leaves.
Economic Importance for Humans: Negative
none
Economic Importance for Humans: Positive
Tropical rainforest species are slowly being recognized for their potential to further human medicine. Sloths may be important in this respect for their ability to heal quickly and avoid infection. Sloths are able to survive the most severe injuries: deep wounds rarely become infected and heal completely within weeks. Understanding the basis of this healing response may one day help in treating severe wounds.
Conservation Status
B. torquatus is extinct through much of its former range and is now confined to small areas of Brazilian Atlantic rainforest. It is still threatened by continuing deforestation.
Other Comments
Sloths are renowned for their slow, ponderous movements. They have a metabolic rate 40-45% that expected of an animal their size, and they take days to process an amount of food that other ruminants could process in hours. They have considerably reduced muscle mass, presumably to make room for the expansive gut, and are therefore unable to regulate body temperature by shivering. They have a low (30-34 degrees C) body temperature that they regulate by basking in the sun.
Contributors
Sharon Jansa 
(author), University of Minnesota.
