The three-toed sloth can hang so securly with its hooklike claws that it even falls asleep in this position. A sloth may even stay suspended in the trees for some time after it dies. Bradypus tridactylus needs relatively little food and has a lower rate of metabolism than do other mammals found about the same size. It has very little muscle and at night, a sloth's body temperature drops as much as 12 degrees in order to preserve energy. The three-toed sloth is related to anteaters and armadillos, although commonly it is mistakenly thought to be related to monkeys. As a result of the extra vertebrae in its neck, Bradypus tridactylus can rotate its head 270 degrees. Bradypus tridactylus is home to a variety of creatures. Beetles, mites, moths, and algae can be found residing in the sloth's unusual fur. Indirectly, the sloth provides a home and nourishment for insects that are responsible for the decomposition of waste ( World Book, 1996;Journal of Nat. History vol. 105 and 87)
Perception Channels: tactile ; chemical
Bradypus tridactylus has become so highly specialized for arboreal life that it is severly handicapped if removed from the forest canopy. Also, this mammal does not survive in captivity very well. With the rapid decimation of the rain forests, due to the activities of lumber companies and a growing number of farmers and miners, these mammals will certainly be affected (www. geocites.com/Hollwood/set/1478/Sloth.html).
IUCN Red List of Threatened Species: least concern
The three-toed sloth in its remote habitat rarely has the chance to affect a human life. It is food to jaguars and ocelots, from which skins are used for human enjoyment. (www.geocites.com/Hollwood/set/1478/Sloth.html).
The three-toed sloth is herbivorous. It feeds exclusively on twigs, buds, and leaves of trees of the genus Cecropia. Because of its limited diet, the species does not do well in captivity ( http://www.geocites.com/Hollwood/set/1478/Sloth.html , 1996).
The three-toed sloth inhabits tropical rain forests from southern Central America to north-eastern Argentina ( http://www.ed.final.gov/linc/spring96/projects/rainforest/rainhtual1996).
Biogeographic Regions: neotropical (Native )
The three-toed sloth lives high in the canopy of tropical rainforests (www.hillside.sowashco/95-96/palmquist/rainforest/rainhtual).
Terrestrial Biomes: rainforest
Bradypus tridactylus is a strange animal. It has almost no tail or external ears, and its head is slightly rounded with a blunt nose. The body is covered with long and course hair. Very small green algae sometimes live mutualistically in the pits of the hair, which gives the sloth an overall greenish appearance that camouflouges it in the forest canopy. Male sloths have a bright yellow or orange patch on the back. The females have two mammae in the chest region. The three-toed sloth is armed with long, compressed, arched, hollowed claws, of which the middle claw is the largest. Bradypus tridactylus grows to a length of between 1.5 and 2.5 ft. The limbs are long and weak, with anterior extremities that are nearly double the length of the posterior. The three-toed sloth has 9 neck vertebrate, which grant it extreme flexibility (Cuvier).
Range mass: 2.25 to 5.5 kg.
Other Physical Features: endothermic ; bilateral symmetry
Bradypus tridactylus mates high in the safety of the trees. After birth the males do not display any parental care. It gives birth to a single, very small young, usually in the beginning of the dry season, March - April. Gestation typically lasts 5-6 months. After birth, the offspring enjoys belly-to-belly nurturing for six months. At four months, it can begin to feed on foliage, having first sampled it at two weeks of age from its mother's lips. Sloths inherit not only their mother's preference for particular kinds of leaves but also the specialized gut flora to digest them. When a young sloth has mastered the rudiments of arboreal life, its mother simply departs, leaving it to its life in the tropical canopy (World Book,1996; www.press.jhu.edu/books/walker/).
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); sexual
Average gestation period: 141 days.
Average number of offspring: 1.
Average age at sexual or reproductive maturity (male)
Sex: male: 1095 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 1642 days.
Although unable to survive outside the tropical rainforests of South and Central America, within that environment sloths are outstandingly successful creatures. They can account for as much as half the total energy consumption and two-thirds of the total terrestrial mammalian biomass in some areas. Of the six species, only one, the Maned Three-toed Sloth, has a classification of ‘endangered’ at present. The ongoing destruction of South Americas forests, however, may soon prove a threat to the others.
The pale-throated sloth (Bradypus tridactylus), occasionally known as the ai (/ˈɑːi/),[4] is a species of three-toed sloth that inhabits tropical rainforests in northern South America.
It is similar in appearance to, and often confused with, the brown-throated sloth, which has a much wider distribution. Genetic evidence has been interpreted to suggest the two species diverged only around 400,000 years ago, although the most recent evidence indicates the split was closer to 6 million years.[5][6]
Pale-throated sloths have a rounded head with a blunt nose and small external ears. The limbs are long and weak, with the arms being nearly twice the length of the hindlimbs. The hands and feet each have three digits, armed with long, arched claws, with the middle claw being the largest and most powerful. Males are 45 to 55 centimetres (18 to 22 in) in head-body length, with a short, 4 to 6 centimetres (1.6 to 2.4 in), tail, and weigh from 3.2 to 6 kilograms (7.1 to 13.2 lb). However, the females are noticeably larger, being from 50 to 75 centimetres (20 to 30 in) in length, and weighing 3.8 to 6.5 kilograms (8.4 to 14.3 lb).[7]
The body is covered with coarse guard hairs up to 10 centimetres (3.9 in) long, with a finer undercoat. Green algae live mutualistically between the microscopic scales on the surface of the guard hairs, giving the sloth a somewhat greenish appearance that serves as camouflage. Adults are blackish-grey over most of the body, with darker patches distributed over the backs, shoulders, and hips. Males have a bright yellow or orange patch on the back, divided by a central black stripe. Pale-throated sloths are difficult to distinguish from the closely related brown-throated sloth, but, as their name implies, have a pale yellow patch on the throat.[7]
The eyes are large and forward facing for binocular vision, with round pupils. Unusually, they appear to lack any cone cells in the retina, suggesting that the sloth is unable to see color. Despite its apparently small ears, the pale-throated sloth has excellent hearing; it has also been reported to have a good sense of smell.[7]
The sloth has nine cervical vertebrae, giving it extreme flexibility. As a result, a pale-throated sloth can bend its head backwards and forwards through 270° and rotate it through 330°. It possesses a pair of foramina in the anterodorsal nasopharynx, a feature that distinguishes it from its sister species. The females have two mammae in the chest region, a simple uterus. Males have no discrete prostate gland, no scrotum, and only rudimentary seminal vesicles.[7]
The mouth is lined by a black mucosa, although the large and heavy tongue is pink. The palate is wrinkled in texture, and the tongue is lined with numerous grooves, apparently adaptations to the sloth's diet. Like other three-toed sloths, it has just five teeth on each side of the upper jaw, and four on each side of the lower jaw; these are all simple and rounded in shape, with the front teeth in the upper jaw being much smaller than the others. The esophagus is short, but the stomach is large and complex, and there is also a large diverticulum in the cecum.[7]
The pale-throated sloth is found only in the tropical forests of northern South America, including Guyana, Suriname, French Guiana, eastern Venezuela and Brazil north of the Amazon River.[2] There are no recognised subspecies.
Pale-throated sloths are solitary,[8] herbivorous animals that spend almost their entire lives in trees. Depending on habitat, population densities of anything from 1.7 to 221 per square kilometre (4.4 to 572.4/sq mi) have been reported.[2] They eat only leaves, twigs, and buds of the trees of Cecropia, Ceiba, Elizabetha, and Hevea.[9] Known predators include jaguars, margays, harpy eagles, and anacondas.[7]
The pale-throated sloth can hang so securely with its hooklike claws that it even falls asleep in this position. It may even stay suspended in the trees for some time after it dies. They have been reported to spend over eighteen hours each day asleep, and move through the tree canopy only very slowly. They periodically descend from the trees to defecate, depositing a pile of small pellets in a hole dug into the ground. Despite their arboreal lifestyle, they are effective swimmers. Their call is a bird-like whistle described as an "ai-ai" sound.[7]
In addition to their mutualism with green algae, pale-throated sloths are also commensal with sloth moths, and with certain species of beetle. These insects live in the sloth's fur, and lay their eggs in its dung, on which their larvae feed.[7]
Mating takes place in the trees, with the pair either face to face, or with the male on the female's back. The female gives birth to a single infant after a gestation period of about six months.[10]
The young are born already fully furred, and with open eyes. The young animal clings to the mother's underside for the first month of life, by which time it has reached a weight of around 300 grams (10 oz). They begin to take solid food at three weeks, and are fully weaned some time after the first month. The young initially have soft greyish-brown fur, which darkens and becomes rougher as they age.[7] They reach sexual maturity at around three years.[10]
The pale-throated sloth (Bradypus tridactylus), occasionally known as the ai (/ˈɑːi/), is a species of three-toed sloth that inhabits tropical rainforests in northern South America.
It is similar in appearance to, and often confused with, the brown-throated sloth, which has a much wider distribution. Genetic evidence has been interpreted to suggest the two species diverged only around 400,000 years ago, although the most recent evidence indicates the split was closer to 6 million years.
