Rhinoceros (IPA: /raɪˈnɒsərəs/), often colloquially abbreviated rhino, is a name used to group five extant species of odd-toed ungulates in the family Rhinocerotidae. Two of these species are native to Africa and three to southern Asia. Three of the five species—the Javan, Sumatran and Black Rhinoceros—are critically endangered. The Indian is endangered, with fewer than 2700 individuals remaining in the wild. The White is registered as Vulnerable, with over 9,000 remaining in the wild.
The rhinoceros family is characterised by large size (one of the largest remaining megafauna alive today) with all of the species able to reach one ton or more in weight; herbivorous diet; and 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 (400–600g); 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 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.
The rhino is prized for its horn. The horns of a rhinoceros are made of keratin, the same type of protein that makes up hair and fingernails. Both African species and the Sumatran Rhinoceros have two horns, while the Indian and Javan Rhinoceros have a single horn. Rhinoceroses have acute hearing and sense of smell, but poor eyesight. Most live to be about 60 years old or more.
Taxonomy and naming
The word "rhinoceros" (ῤινόκερως) is derived from the Greek words ῥινός rhinos, meaning nose, and κέρας keras, meaning horn; hence "horned-nose". The plural can be rhinoceros, rhinoceri, rhinoceroses, or rhinoceroi. The collective noun for a group of rhinoceros is "crash". They are commonly known as rhinos.
The five living species fall into three categories. The two African species, the White Rhinoceros and the Black Rhinoceros, diverged during the early Pliocene (about 5 million years ago) but the Dicerotini group to which they belong originated in the middle Miocene, about 14.2 million years ago. The main difference between black and white rhinos is the shape of their mouths. White rhinos have broad flat lips for grazing and black rhinos have long pointed lips for eating foliage. A popular, if unverified theory, claims that the name White Rhinoceros was actually a mistake, or rather a corruption of the word wijd ("wide" in Afrikaans), referring to their square lips.
White Rhinoceros are divided into Northern and Southern subspecies. There are two living Rhinocerotini species, the endangered Indian Rhinoceros and the critically endangered Javan Rhinoceros, which diverged from one another about 10 million years ago. The critically endangered Sumatran Rhinoceros is the only surviving representative of the most primitive group, the Dicerorhinini, which emerged in the Miocene (about 20 million years ago). The extinct Woolly Rhinoceros of northern Europe and Asia was also a member of this tribe.
A subspecific hybrid white rhino (Ceratotherium s. simum × C. s. cottoni) was bred at the Dvůr Králové Zoo (Zoological Garden Dvur Kralove nad Labem) in the Czech Republic in 1977. Interspecific hybridisation of Black and White Rhinoceros has also been confirmed.
All rhinoceros species have 82 chromosomes (diploid number, 2N, per cell), except the Black Rhinoceros, which has 84. This is the highest known chromosome number of all mammals.
White Rhinoceros
The White Rhinoceros or Square-lipped Rhinoceros (Ceratotherium simum) is, after the elephant, the most massive remaining land animal in the world, along with the Indian Rhinoceros and the hippopotamus, which are of comparable size. There are two subspecies of White Rhinos; as of 2005, South Africa has the most of the first subspecies, the Southern White Rhinoceros (Ceratotherium simum simum). The population of Southern White Rhinos is about 14,500, making them the most abundant subspecies of rhino in the world. However, the population of the second subspecies, the critically-endangered Northern White Rhinoceros (Ceratotherium simum cottoni), is down to as few as four individuals in the wild, and as of June 2008 this sub-species could even be extinct.
The White Rhino has an immense body and large head, a short neck and broad chest. This rhino can exceed 3000 kg (6600 pounds), have a head-and-body length of 3.35-4.2 m (11-13.9 feet) and a shoulder height of 150-185 cm (60-73 inches). The record-sized White Rhinoceros was about 4500 kg (10,000 lb).. On its snout it has two horns. The front horn is larger than the other horn and averages 89.9 cm (23.6 inches) in length and can reach 150 cm (59 inches). The White Rhinoceros also has a noticeable hump on the back of its neck which supports its large head. The colour of this animal ranges from yellowish brown to slate grey. The only hair on them is on the ear fringes and tail bristles with little across the body. White Rhinos have the distinctive flat broad mouth which 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 those two species are not really distinguishable by colour. 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 tentatively declared extinct in 2006. Only 8 of this subspecies are left in existence, all in captivity.
An adult Black Rhinoceros stands 147–160 cm (57.9–63 inches) high at the shoulder and is 3.3-3.6 m (10.8–11.8 feet) in length. An adult weighs from 800 to 1400 kg (1,760 to 3,080 lb), exceptionally to 1820 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 they use to grasp leaves and twigs when feeding.
Indian Rhinoceros
The Indian Rhinoceros or the Great One-horned Rhinoceros (Rhinoceros unicornis) is found in Nepal and in Assam, India. The rhino once inhabited many areas of Pakistan to Burma and may have even roamed in China. But because of human influence their range has shrunk and now they only exist in small populations in north-eastern India , Nepal and in a 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 2200–3000 kg (4,800–6,600 lb). Female Indian rhinos weigh about 1600 kg. The Indian Rhino is from 5.7–6.7 feet tall and can be up to 13 feet (4.0 m) long. The record-sized specimen of this rhino was approximately 3500 kg. The Indian Rhino has a single horn that reaches a length of between 20 and 101 cm. Its size is comparable to that of the White Rhino in Africa.
Two-thirds of the world's Great One-horned Rhinoceroses are now confined to the Kaziranga National Park situated in the Golaghat district of Assam, India.
Javan Rhinoceros
The Javan Rhinoceros (Rhinoceros sondaicus) is one of the rarest and most endangered large mammals anywhere in the world. 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.
Like the closely related larger Indian Rhinoceros, the Javan rhinoceros has only a single horn. Its hairless, hazy gray skin fall 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 (10-10.5 feet), including its head and a height of 1.5–1.7 m (4.9-5.6ft)tall. Adults are variously reported to weigh between 900–1,400 kg or 1,360-2,000 kg. Males horns can reach 26 cm in length while in females they are knobs or no horn at all.
Sumatran Rhinoceros
The Sumatran Rhinoceros (Dicerorhinus sumatrensis) is the smallest extant rhinoceros species, as well as the one with the most fur, which allows it to survive at very high altitudes in Borneo and Sumatra. Due to habitat loss and poaching, its numbers have declined and it is one of the world's rarest mammals. About 275 Sumatran Rhinos are believed to remain.
Typically a mature Sumatran rhino stands about 130 cm (4.3ft) high at the shoulder, a body length of 240–315 cm (7.9ft - 10.3ft) and weighs around 700 kg (1543 lbs), though the largest individuals have been known to weigh as much as 1,000 kilograms. Like the African species, it has two horns; the largest is the front (25–79 cm) and the smaller being the second, which is usually less than 10 cm long. The males have much larger horns than the females. Hair can range from dense (the most dense 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.
(wikipedia.org)
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