Rhinoceros

A rhinoceros ( ry-NOSS-ə-rəss; from Ancient Greek ῥινόκερως (rhinókerōs) 'nose-horned'; from ῥίς (rhis) 'nose' and κέρας (kéras) 'horn'; pl.: rhinoceros or rhinoceroses), commonly abbreviated to rhino, is a member of any of the five extant species (or numerous extinct species) of odd-toed ungulates (perissodactyls) in the family Rhinocerotidae. It is the only living family in the superfamily Rhinocerotoidea (whose members are also sometimes called rhinoceroses; the term true rhinoceroses is sometimes used for Rhinocerotidae). Two of the extant species, the black rhinoceros (Diceros bicornis) and the white rhinoceros (Ceratotherium simum) are native to Africa, while the other three, the Javan rhinoceros (Rhinoceros sondaicus), Indian rhinoceros (Rhinoceros unicornis) and Sumatran rhinoceros (Dicerorhinus sumatrensis) are native to South and Southeast Asia.

Rhinoceroses are some of the largest remaining megafauna: all weigh over half a tonne in adulthood. They have one or two horns, a thick 1.5–5 cm (0.59–1.97 in), protective skin formed from layers of collagen positioned in a lattice structure, and relatively small brains 400–600 g (14–21 oz) for mammals of their size. They have a herbivorous diet, generally eating leafy material, although their ability to ferment food in their hindgut allows them to subsist on more fibrous plant matter when necessary. Unlike other perissodactyls, the two African species of rhinoceros lack teeth at the front of their mouths; they rely instead on their lips to pluck food.

Rhinoceroses are killed by poachers for their horns, which are bought and sold on the black market for high prices, leading to most living rhinoceros species being considered endangered. The contemporary market for rhino horn is overwhelmingly driven by China and Vietnam, where it is bought by wealthy consumers to use in traditional Chinese medicine, among other uses. Rhino horns are made of keratin, the same material as hair and fingernails, and there is no good evidence of any health benefits.