Rhinoceros

Rhinoceros /raɪˈnɒsərəs/, often abbreviated as rhino, is a group of five extant species of odd-toed ungulates in the family Rhinocerotidae. Two of these species are native to Africa and three to southern Asia.
Members of the rhinoceros family are characterized by their large size (they are some of the largest remaining megafauna, with all of the species able to reach one tonne or more in weight); as well as by a herbivorous diet; a thick protective skin, 1.5–5 cm thick, formed from layers of collagen positioned in a lattice structure; relatively small brains for mammals this size (400–600 g); and a large horn. They generally eat leafy material, although their ability to ferment food in their hindgut allows them to subsist on more fibrous plant matter, if necessary. Unlike other perissodactyls, the two African species of rhinoceros lack teeth at the front of their mouths, relying instead on their powerful premolar and molar teeth to grind up plant food.^[1]
Rhinoceros are killed by humans for their horns, which are bought and sold on the black market, and which are used by some cultures for ornamental or (pseudo-scientific) medicinal purposes. The horns are made of keratin, the same type of protein that makes up hair and fingernails.^[2] Both African species and the Sumatran rhinoceros have two horns, while the Indian and Javan rhinoceros have a single horn.

White rhinoceros

There are two subspecies of white rhino: the southern white rhinoceros (Ceratotherium simum simum) and the northern white rhinoceros (Ceratotherium simum cottoni). In 2007, the southern subspecies had a wild population of 17,480 (IUCN2008) - 16,266 of which were in South Africa - making them the most abundant rhino subspecies in the world. However, the northern subspecies was critically endangered, with as few as four individuals in the wild; the possibility of complete extinction in the wild having been noted since June 2008.^[5] Six are known to be held in captivity, two of which reside in a zoo in San Diego. Four born in a zoo in the Czech Republic were transferred to a wildlife refuge in Kenya in December 2009, in an effort to have the animals reproduce and save the subspecies

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 really 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 bicornis) 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.^[10] The native Tswanan name Keitloa is used to describe a South African variation of the black rhino in which the posterior horn is equal to or longer than the anterior horn.^[11]
An adult black rhinoceros stands 150–175 cm (59–69 in) high at the shoulder and is 3.5–3.9 m (11–13 ft) in length.^[12] An adult weighs from 850 to 1,600 kg (1,900 to 3,500 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. 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^[13] in the late 1960s to only 2,410 in 1995.^[14]

Indian rhinoceros

The Indian rhinoceros, or the greater one-horned rhinoceros, (Rhinoceros unicornis) is now found almost exclusively in Nepal and North-Eastern India. The rhino once inhabited many areas ranging from Pakistan to Burma and may have even roamed in China. However, because of human influence, their range has shrunk and now they only exist in several protected areas of India (in Assam, West Bengal, Gujarat and a few pairs in Uttar Pradesh) and Nepal, plus a few pairs in Lal Suhanra National Park in Pakistan. It is confined to the tall grasslands and forests in the foothills of the Himalayas.
The Indian rhinoceros has thick, silver-brown skin which creates huge folds all over its body. Its upper legs and shoulders are covered in wart-like bumps, and it has very little body hair. Fully grown males are larger than females in the wild, weighing from 2,500–3,200 kg (5,500–7,100 lb).The Indian rhino stands at 1.75–2.0 metres (5.75–6.5 ft). Female Indian rhinos weigh about 1,900 kg and are 3–4 metres long. The record-sized specimen of this rhino was approximately 3,800 kg. The Indian rhino has a single horn that reaches a length of between 20 and 100 cm. Its size is comparable to that of the white rhino in Africa.
Two-thirds of the world's Indian rhinoceroses are now confined to the Kaziranga National Park situated in the Golaghat district of Assam, India.^[15]

Javan rhinoceros

The Javan rhinoceros (Rhinoceros sondaicus) is one of the rarest and most endangered large mammals anywhere in the world.^[16] According to 2002 estimates, only about 60 remain, in Java (Indonesia) and Vietnam. Of all the rhino species, the least is known of the Javan Rhino. These animals prefer dense lowland rain forest, tall grass and reed beds that are plentiful with large floodplains and mud wallows. Though once widespread throughout Asia, by the 1930s the rhinoceros was nearly hunted to extinction in India, Burma, Peninsular Malaysia, and Sumatra for the supposed medical powers of its horn and blood. As of 2009, there are only 40 of them remaining in Ujung Kulon Conservation, Java, Indonesia. The last rhinoceros in Vietnam was reportedly killed in 2010.^[17]
Like the closely related, and larger, Indian rhinoceros, the Javan rhinoceros has a single horn. Its hairless, hazy gray skin falls into folds into the shoulder, back, and rump giving it an armored-like appearance. The Javan rhino's body length reaches up to 3.1–3.2 m (10–10 ft), including its head and a height of 1.5–1.7 m (4 ft 10 in–5 ft 7 in) tall. Adults are variously reported to weigh between 900–1,400 kg^[18] or 1,360–2,000 kg.^[19] Male horns can reach 26 cm in length, while in females they are knobs or are not present at all.^[19

Sumatran rhinoceros

The Sumatran rhinoceros (Dicerorhinus sumatrensis) is the smallest extant rhinoceros species, as well as the one with the most hair. It can be found at very high altitudes in Borneo and Sumatra. Due to habitat loss and poaching, its numbers have declined and it is the most threatened rhinoceros. About 275 Sumatran rhinos are believed to remain.
A mature Sumatran rhino typically stands about 130 cm (51 in) high at the shoulder, with a body length of 240–315 cm (94–124 in) and weighing around 700 kg (1,500 lb), though the largest individuals have been known to weigh as much as 1,000 kilograms. Like the African species, it has two horns; the larger is the front (25–79 cm), with the smaller usually less than 10 cm long. The males have much larger horns than the females. Hair can range from dense (the densest hair in young calves) to scarce. The color of these rhinos is reddish brown. The body is short and has stubby legs. They also have a prehensile lip.^]