Rhinoceros are killed by humans for their horns, which are bought and sold on the black market, are used by some cultures for ornamental or (largely pseudo-scientific) medicinal purposes. The horns 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.
The IUCN Red List identifies three of the species as "critically endangered".
Taxonomy and naming
The word rhinoceros is derived through Latin from the Ancient Greek: ?????????, which is composed of ????- (rhino-, "nose") and ????? (keras, "horn"). The plural in English is rhinoceros orrhinoceroses. The collective noun for a group of rhinoceroses is crash or herd.
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 wyd ("wide" in Afrikaans), referring to their square lips.
White Rhinoceros
The White 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 thehippopotamus, 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 are thought to have become extinct in the wild. Six are known to be held in captivity, two of which reside in a zoo in San Diego. There are currently four that were in held in captivity since 1982 in a zoo in the Czech Republic which were transferred to a wildlife refuge in Kenya in December 2009, in an effort to have the animals reproduce and save the subspecies.
The White Rhino has an immense body and large head, a short neck and broad chest. This rhino can exceed 3,500 kg (7,700 lb), have a head-and-body length of 3.5–4.6 m (11–15 ft) and a shoulder height of 1.8–2 m (5.9–6.6 ft) The record-sized White Rhinoceros was about 4,530 kg (10,000 lb). 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 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 theWhite 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.
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. 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 they use 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 in the late 1960s to only 2,410 in 1995.
Predators
In the wild, adult rhinoceros have few natural predators other than humans. Young rhinos can fall prey to predators such as big cats, crocodiles, wild dogs, and hyena. Although rhinos are of large size and have a reputation of being tough, they are actually very easily poached. Because it visits water holes daily, the rhinoceros is easily killed while taking a drink. As of December 2009 poaching has been on a "global" increase whilst efforts to protect the rhinoceros are being considered increasingly ineffective. The worst estimate, that only 3% of poachers are successfully countered, is reported of Zimbabwe. Rhino horn is considered to be particularly effective on fevers and even "life saving" by traditional Chinese medicine practitioners, which in turn provides a sales market. Nepal is apparently alone in avoiding the crisis while poacher-hunters grow ever more sophisticated. South African officials are calling for urgent action against rhinoceros poaching after poachers killed the last female rhinoceros in Krugersdorp Park near Johannesburg.
Horns
Rhinoceros horns, unlike those of other horned mammals, consist of keratin only and lack a bony core, such as bovine horns. Rhinoceros horns are used in traditional Asian medicine, and for dagger handles inYemen and Oman. Esmond Bradley Martin has reported on the trade for dagger handles in Yemen.
One repeated misconception is that rhinoceros horn in powdered form is used as an aphrodisiac in Traditional Chinese Medicine (TCM) as Cornu Rhinoceri Asiatici (??). It is, in fact, prescribed for fevers and convulsions. Neither have been proven by evidence-based medicine. Discussions with TCM practitioners to reduce its use have met with mixed results since some TCM doctors mistakenly see rhinoceros horn as a life-saving medicine of better quality than substitutes. China has signed the CITES treaty however. To prevent poaching, in certain areas, rhinos have been tranquilized and their horns removed. Many rhino range States have stockpiles of rhino horn.
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