Rhinoceros

A rhinoceros (/raɪˈnɒsərəs/, from Greek rhinokerōs 'nose-horned', from rhis 'nose', and keras 'horn'), commonly abbreviated to rhino, is a member of any of the five extant species (or numerous extinct species) of odd-toed ungulates in the family Rhinocerotidae. (It can also refer to a member of any of the extinct species of the superfamily Rhinocerotoidea.) Two of the extant species are native to Africa, and three to South and Southeast Asia.

Rhinoceroses are some of the largest remaining megafauna: all weigh at least one tonne in adulthood. They have a herbivorous diet, small brains (400–600 g) for mammals of their size, one or two horns, and a thick (1.5–5 cm), protective skin formed from layers of collagen positioned in a lattice structure. They generally eat 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.

Rhinoceros 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. A market also exists for rhino horn dagger handles in Yemen, which was the major source of demand for rhino horns in the 1970s and 1980s.

White rhinoceros

There are two subspecies of white rhinoceros: the southern white rhinoceros (Ceratotherium simum simum) and the northern white rhinoceros (Ceratotherium simum cottoni). As of 2013, the southern subspecies have a wild population of 20,405—making them the most abundant rhino subspecies in the world. However, the northern subspecies are critically endangered, with all that is known to remain being two captive females. There is no conclusive explanation of the name "white rhinoceros". A popular idea that "white" is a distortion of either the Afrikaans word wyd or the Dutch word wijd (or its other possible spellings whyde, weit, etc.,), meaning "wide" and referring to the rhino's square lips, is not supported by linguistic studies.[11][12]

The white rhino has an immense body and large head, a short neck, and a broad chest. Females weigh 1,600 kg (4,000 lb) and males 2,400 kg (5,000 lb). The head-and-body length is 3.5–4.6 m (11–15 ft) and the shoulder height is 1.8–2 m (5.9–6.6 ft). On its snout, it has two horns. The front horn is larger than the other horn and averages 90 cm (35 in) in length and can reach 150 cm (59 in). The white rhinoceros also has a prominent muscular hump that supports its relatively large head. The colour of this animal can range from yellowish-brown to slate grey. Most of its body hair is found on the ear fringes and tail bristles, with the rest distributed rather sparsely over the rest of the body. White rhinos have a distinctive flat broad mouth that is used for grazing.

Black rhinoceros

The name "black rhinoceros" (Diceros bicornis) was chosen to distinguish this species from the white rhinoceros (Ceratotherium simum). This can be confusing, as the two species are not truly distinguishable by color. There are four subspecies of black rhino: South-central (Diceros bicornis minor), the most numerous, which once ranged from central Tanzania south through Zambia, Zimbabwe, and Mozambique to northern and eastern South Africa; South-western (Diceros bicornis occidentalis) which are better adapted to the arid and semi-arid savannas of Namibia, southern Angola, western Botswana, and western South Africa; East African (Diceros bicornis Michaeli), primarily in Tanzania; and West African (Diceros bicornis longipes) which was declared extinct in November 2011.[13] The native Tswanan name keitloa describes a South African variation of the black rhino in which the posterior horn is equal to or longer than the anterior horn.[14]

An adult black rhinoceros stands 1.50–1.75 m (59–69 in) high at the shoulder and is 3.5–3.9 m (11–13 ft) in length.[15] An adult weighs from 850 to 1,600 kg (1,870 to 3,530 lb), exceptionally to 1,800 kg (4,000 lb), with the females being smaller than the males. Two horns on the skull are made of keratin with the larger front horn typically 50 cm long, exceptionally up to 140 cm. Sometimes, a third smaller horn may develop.[16] The black rhino is much smaller than the white rhino and has a pointed mouth, which it uses to grasp leaves and twigs when feeding.

During the latter half of the 20th century, their numbers were severely reduced from an estimated 70,000[17] in the late 1960s to a record low of 2,410 in 1995. Since then, numbers have been steadily increasing at a continental level with numbers doubling to 4,880 by the end of 2010.[citation needed] However, as of 2008, the current numbers are still 90% lower than three generations ago.

Woolly rhinoceros

The woolly rhinoceros (Coelodonta antiquitatis) is an extinct species of rhinoceros that was common throughout Europe and Asia during the Pleistocene epoch and survived until the end of the last glacial period. The woolly rhinoceros was a member of the Pleistocene megafauna.

The woolly rhinoceros was covered with long, thick hair that allowed it to survive in the extremely cold, harsh mammoth steppe. It had a massive hump reaching from its shoulder and fed mainly on herbaceous plants that grew in the steppe.

Mummified carcasses preserved in permafrost and many bone remains of woolly rhinoceroses have been found. Images of woolly rhinoceroses are found among cave paintings in Europe and Asia.