sloth
Sloth is the common name for any of the slow-moving, New World arboreal mammals comprising the families Megalonychidae (two-toed sloths) and Bradypodidae (three-toed sloths) of the order Pilosa. [1]
The brown-throated three-toed sloth (Bradypus variegatus) can be identified and distinguished from other members of its genus by the brown color of its fur on the sides of its face and throat, prominent dark brown forehead, suborbital stripe outlining the ocular area of the face and shorter mandibular spout (Wetzel and Koch 1973; Wetzel and Avila-Pires 1980). [2]
The living sloths comprise six species of medium-sized mammals belonging to the families Megalonychidae and Bradypodidae, part of the order Pilosa. [3]
About 2 ft (60 cm) long, sloths have a tiny tail, peglike teeth, long curved claws, and long forelimbs. [4]
This 40-year-old female is one of three Linn?’s two-toed sloths (Choloepus didactylus) now living at the Zoo, but since 1950, a total of 18 sloths have called the Zoo home. [5]
Average total body length (108 animals studied)’578 mm (length ranging between 420-800mm). [2]
The three-toed sloth (Bradypus) is about the size of a house cat, with a dense, furry coat and yellowish face. [4]
The few exceptions include manatees and two-toed sloths, which each have only six cervical vertebrae, and three-toed sloths with nine cervical vertebrae. [...] Of the six living species, only one, the Maned Three-toed Sloth (Bradypus torquatus), has a classification of “endangered” at present. [3]
And because muscle is heavy, sloths weigh far less than other mammals their size. [5]
The four living species of Bradypodidae are about the size of a small dog and are characterized by three-clawed digits on their forelimbs and a short tail. [...] The fur of sloths is a special ecosystem that is home to many insects’sometimes hundreds of beetles’and they have a mutually beneficial symbiotic relationship with algae, providing a habitat for algae while the green color added to the fur helps to camouflage the sloths. [1]
The two species of two-toed sloths, or unaus (Choloepus), have two toes on the forelimbs; they eat fruits, stems, and leaves of various plants. [4]
Until geologically recent times, ground sloths such as Megatherium lived in South America and parts of North America, but along with many other animals they disappeared immediately after the arrival of humans on the continent. [3]
In the midst of the Smithsonian National Zoo’s Amazonia exhibit, a mammal as large as a raccoon but only half as heavy hangs upside down from a slender tree branch. [5]
Sources:
[1] Sloth - New World Encyclopedia
[2] Biogeography of the Brown-throated Three-toed Sloth (Bradypus variegatus)
[3] Sloth - Wikipedia, the free encyclopedia
[4] sloth: Information from Answers.com
[5] At the Zoo: Slow and Steady Sloths - National Zoo| FONZ