Bradypus

Superregnum: Eukaryota
Cladus: Opisthokonta
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Classis: Mammalia
Subclassis: Theria
Infraclassis: Placentalia
Ordo: Pilosa
Subordo: Folivora
Familia: Bradypodidae
Genus: Bradypus
Species: B. pygmaeus - B. torquatus - B. tridactylus - B. variegatus

Name

Bradypus Linnaeus, 1758

Type species: B. tridactylus Linnaeus, 1758

Synonyms

* Achaeus Erman, 1835
* Acheus F. Cuvier, 1825
* Arctopithecus Gray, 1850
* Eubradypus Lönnberg, 1942
* Hemibradypus Anthony, 1906
* Ignavus Blumenbach, 1779
* Scaeopus Peters, 1864

Vernacular names

References

* Bradypus on Mammal Species of the World.
* Mammal Species of the World: A Taxonomic and Geographic Reference, 2 Volume Set edited by Don E. Wilson, DeeAnn M. Reeder
* Linnaeus: Systema Naturae, 10th ed., 1: 34.

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The three-toed sloths are the only members of the Bradypus genus and the Bradypodidae family. There are four living species of three-toed sloths. These are the Brown-throated Sloth, the Maned Sloth, the Pale-throated Sloth, and the Pygmy Three-toed Sloth.

Although similar to the somewhat larger and generally faster moving two-toed sloths, the two genera are not particularly closely related.[2] Recent phylogenetic analyses support the morphological data from the 1970s and 1980s that the two genera are not closely related and that each adopted their arboreal lifestyles independently.[3] It is unclear what, if any, ground-dwelling sloth taxa the three-toed sloths evolved from, but the two-toed sloths likely evolved from one of the Caribbean megalonychids.[4] Both types of sloth tend to occupy the same forests: in most areas, a particular single species of three-toed sloth and a single species of the larger two-toed type will jointly predominate. Famously slow-moving, the sloth travels at a top speed of 0.24 km/h (0.15 mph).[5]

Although they are quite slow in trees, three-toed sloths are agile swimmers. The offspring cling to their mother's bellies for around 9 months or so. They cannot walk on all four, therefore, they must use their front arms and claws to drag themselves across the tropical rain forest floor. Scientists do not know exactly when these mammals mate, but it is estimated to be somewhere around March or February.

The three-toed sloth is almost totally arboreal ("tree-dwelling"), with a body "built to hang." It lives in the shrub or lower tree layer, but sometimes moves to the canopy. Its long, coarse, grayish-brown fur often appears greenish, not due to pigment but to algae growing on it. The sloth’s greenish color and its sluggish habits provide an effective camouflage: hanging quietly, the sloth resembles a bundle of leaves. Large curved claws help the sloth to keep a strong grip on tree branches.[5]
Characteristics

Three-toed sloths are about the size of a small dog or large cats, with the head and body having a combined length of around 45 cm, and the animal having a weight of 3.5--4.5 kg (or between 7--10 lbs). Unlike the two-toed sloths, they also have a short (6--7 cm) tail, and they have three clawed toes on all front feet of their limbs. They move between different trees up to four times a day, although they prefer to keep to a particular type of tree, which varies between individuals, perhaps as a means of allowing multiple sloths to occupy overlapping home ranges without competing with each other.[6] Three-toed sloths have no incisor or canine teeth, just a set of peg-shaped cheek teeth that are not clearly divided into premolars and molars, and lack homology with those teeth in other mammals and are thus referred to as molariforms. The molariform dentition in three-toed sloths is simple and can be characterized as dental formula of: Upper: 5, lower: 4-5

The three-toed sloth, unlike most other mammals, does not maintain a constant body temperature, being closer to a reptile in this respect. Because its body temperature goes down as the air temperature goes down, the three-toed sloth is only able to live in humid and warm environments.

Females give birth to a single young after a gestation period of around six months. They are weaned at about one month of age, but remain with the mother for several further months. Adults are solitary, and mark their territories using anal scent glands and dung middens.[6]

Species

* Bradypus pygmaeus – Pygmy Three-toed Sloth
* Bradypus torquatus – Maned Three-toed Sloth
* Bradypus tridactylus – Pale-throated Three-toed Sloth
* Bradypus variegatus – Brown-throated Three-toed Sloth

References

1. ^ Gardner, Alfred (2005-11-16). Wilson, D. E., and Reeder, D. M.. ed. Mammal Species of the World (3rd ed.). Baltimore: Johns Hopkins University Press. pp. 100-101. ISBN 0-801-88221-4. http://www.bucknell.edu/msw3.
2. ^ "3-Toed Sloths". http://xenarthra.org/sloth/bradypus/. Retrieved 2007-04-09.
3. ^ Hoss, Matthias; Dilling, Amrei; Currant, Andrew; Paabo, Svante (9 Jan 1996). "Molecular phylogeny of the extinct ground sloth Mylodon darwinii". Proceedings of the National Academy of Sciences 93 (1): 181–185. doi:10.1006/mpev.2000.0860. http://www.pnas.org/content/93/1/181.abstract. Retrieved 2009-12-28.
4. ^ White, JL and MacPhee, RDE. 2001. The sloths of the West Indies: a systematic and phylogenetic review. Pp. 201-235 in CA Woods and FE Sergile (Eds). Biogeography of the West Indies: Patterns and Perspectives
5. ^ a b http://www.infoplease.com/ipa/A0004737.html
6. ^ a b Dickman, Christopher R. (1984). Macdonald, D.. ed. The Encyclopedia of Mammals. New York: Facts on File. pp. 776–779. ISBN 0-87196-871-1.