Bradypus tridactyluspale-throated three-toed sloth

Geographic Range

The three-toed sloth inhabits tropical rain forests from southern Central America to north-eastern Argentina (


The three-toed sloth lives high in the canopy of tropical rainforests (www.hillside.sowashco/95-96/palmquist/rainforest/rainhtual).

Physical Description

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
    4.96 to 12.11 lb


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;

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • sexual
  • Average number of offspring
  • Average gestation period
    141 days
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    1642 days
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    1095 days


The three-toed sloth is usually solitary. Its dense pelage and camouflaging colors provide it with some defense. It also defends itself from predators like jaguars with its long arms, sharp claws, and sharp teeth. This sloth is strictly arboreal and does not live outside of the forest. Bradypus tridactylus is characterized by its excessively slow locomotion. It would take nearly a month for this animal to travel a single mile. The three-toed sloth sleeps 19 hours a day, hanging upside down from the branches. It also eats, mates, and gives birth in the canopy; all of these activities it performs quietly. During the rare times it drops to the ground, it moves by dragging itself by its hands. The sloth can stand on its feet, but cannot walk on them. Surprisingly though, the three-toed sloth is an excellent swimmer. ( Cuvier, no date;

Communication and Perception

Food Habits

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 ( , 1996).

Economic Importance for Humans: Positive

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. (

Conservation Status

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.

Other Comments

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)


Kelly Hughes (author), University of Michigan-Ann Arbor.



living in the southern part of the New World. In other words, Central and South America.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


uses smells or other chemicals to communicate


animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.


having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.


rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.


reproduction that includes combining the genetic contribution of two individuals, a male and a female


uses touch to communicate


Arias, Ron. "Alone in Amazonia." The Journal of Natural History. Volume 87, (1989). 19-24

Gould, Stephen Jay. "Can We Truly Know Sloth and Rapacity?" The Journal of Natural History. Volume 105, (1996) 18-26

World Book Inc. 1996 World Book Encyclopedia. Seventeeth edition. World Book Inc., New York. 37-38

Cuvier, B. No date Cuvier's Animal Kingdom. Third Edition. Geo. B. Whittaker, London.

http://www.hillside.sowashco/95-96/palmquist/rainforest/rainhtual 96/projects/rainforestwalk/htual