Rhinoceroses

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rhinoceros massive hoofed mammal of Africa, India, and SE Asia, characterized by a snout with one or two horns. The rhinoceros family, along with the horse and tapir families, forms the order of odd-toed hoofed mammals. The five living species, which once ranged widely across Africa and Asia, now consist of remnant populations in protected or remote areas. All are listed as endangered, with the exception of one subspecies of the white rhinoceros.

The skin of the rhinoceros is extremely thick, nearly hairless in most species, and deeply folded in some. The horns, arising from the skin, are made of keratin, a fibrous substance. The legs are stout and short and end in broad feet, each with three toes. Rhinoceroses are herbivorous, browsers or grazers according to the species. Most live near water and like to wallow in mud; all swim well. They have poor vision but good hearing and a good sense of smell. Mostly solitary animals, they feed by night and in the early morning and evening; they rest in shade during the heat of the day. They are often accompanied by small tickbirds (oxpeckers) that feed on parasites in their skin and, by their cries, alert them to danger. Although most rhinoceroses are placid animals, mothers fiercely protect their offspring.

Rhinoceros Species

Two of the five rhinoceros species are African and three Asian. The African species have two horns, one behind the other, and their skins are gray and smooth rather than folded. The black rhinoceros, Diceros bicornis, of E and S Africa, has declined in numbers from about 65,000 in 1970 to 3,600 in 2004 (a total that represents an increase from the mid-1990s low of 2,400); the subspecies once found in W Africa is apparently extinct. At the beginning of the 20th cent. there were 2 to 3 million black rhinoceroses. The black rhinoceros has a grasping upper lip, used for browsing shrubbery. Its front horn may be over 18 in. (45 cm) long. Unpredictable and sometimes dangerous, it can turn and charge with great force if irritated. The white, or square-lipped, rhinoceros, Ceratotherium simum, is divided into two subspecies: the northern white rhinoceros, which may be extinct in the wild, and the southern white rhinoceros, which is found primarily in South Africa; the term white may be a corruption of the Afrikaans word for "wide," referring to its broad snout. The white rhinoceros is second in size among land mammals to the elephant. It stands 6 1/2 ft (2 m) at the shoulder, is 13 ft (4 m) long, and weighs 3 to 4 tons (2,700–3,600 kg). More than half of the world's remaining rhinoceroses are of the southern white subspecies.

Two of the Asian species have a single horn. The Indian rhinoceros, Rhinoceros unicornis, is the second largest rhinoceros and can weigh over 2 tons (1,820 kg). Its thick hide is deeply creased in places, creating the impression of armor plates; folds of thinner skin allow body movement and flexibility. Indian rhinos have reached speeds of 30 mph (48 kph) in charges. Perhaps 2,000 live on the grassy plains of Bengal, Assam, and Nepal, some of them in groups. Their population hit a low point in 1970 at 900. The solitary and smaller Javan rhinoceros, R. sondaicus, is nearly extinct. The Sumatran rhinoceros, Dicerorhinus sumatrensis, also critically endangered, is the only rhinoceros with a hairy coat and the only Asian species with two horns. Smallest of the rhinoceroses, it stands 4 1/2 ft (1.4 m) and weighs about 1 ton (900 kg). Fewer than 400 survive in remote forests of Sumatra, the Malay Peninsula, and Borneo.

Endangered Status

Rhinoceroses are endangered and close to extinction due to loss of their natural habitats to expanding human settlement and agriculture, and especially because of poaching and illegal trade in rhinoceros horns. The horns are believed in Asian traditions to have aphrodisiac or healing properties. They have commanded a very high price for centuries, sometimes surpassing that of gold. Some Middle Eastern societies prize rhinoceros horn for dagger handles. Despite a ban on trade in rhinoceros parts under the Convention on International Trade in Endangered Species (CITES) in 1976, populations declined by 90% over the next 20 years. Unless poaching is stopped, rhinoceros extinction in the wild is virtually inevitable. The poaching problem, exacerbated by poverty and political unrest in many areas, has turned into a war, and dozens of poachers and wildlife sanctuary guards have lost their lives. Aggressive captive breeding programs under way for most species have met with limited success.

Classification

The rhinoceros is classified in the phylum Chordata , subphylum Vertebrata, class Mammalia, order Perissodactyla, family Rhinocerotidae.

Bibliography

See M. Penny, Rhino (1988); S. Fitzgerald, International Wildlife Trade (1989); F. B. Salvadori, Rare Animals of the World (1990).

Rhinocerotidae (rhinoceroses; suborder Ceratomorpha, superfamily Rhinocerotoidea) A family that includes the rhinoceroses and their fossil relatives. They were derived from the Hyracodontidae (‘running rhinoceroses’) in the Eocene and were prominent in the Oligocene, producing a variety of different types. They are characterized by the molarization of the premolars, the enlargement of the first upper and second lower incisors as cutting teeth (subsequently lost in some lines) and the consequent development of a pointed lip and narrow muzzle, and a simple last upper molar. The skeleton is similar to that of elephants, having vertebrae with long neural spines and many ribs so the spine and ribs together form a weight-bearing ‘girder’ resting on the fore limbs and counterbalanced by the weight of the head. All later rhinoceroses have three digits on each limb, but early forms had four. Probably early forms were hornless. While all rhinoceroses tended to large size, some aberrant forms became very large indeed. Paraceratherium (formerly Baluchitherium), a hornless form which lived in Asia during the Oligocene, was about 5.5 m tall at the shoulder, had a long neck and a skull about 1.2 m long and must have weighed about 20 tonnes, making it the largest land mammal ever to have lived. Elasmotherium, which may have possessed a very large horn, was also a large form which lived on the Eurasian plains during the Pleistocene. Coelodonta was the woolly rhinoceros which lived during the Pleistocene. Today there are four genera, and five species: Rhinoceros unicornis, the one-horned Indian form; R. sondaicus, the related Javan species (now very rare); Dicerorhinus sumatrensis, the rare two-horned Sumatran form; and Diceros bicornis and Ceratotherium simum, the African black and white rhinoceroses.

rhinoceros (rhino) Massive, herbivorous mammal native to Africa and Asia. Rhinos are the second largest land mammals (after the hippopotamus). The largest of the five species, the central African white rhino Ceratotherium simum, reaches a height of 2m (1.5ft) at the shoulder. Rhinos have thick skin and poor eyesight, and are solitary grazers or browsers. They like to wallow in muddy pools in the heat. Now rare except in protected areas, rhinos are illegally hunted for their horns (believed to have aphrodisiac properties). Weight: 1–3.5 tonnes. Family Rhinocerotidae.

rhi·noc·er·os / rīˈnäs(ə)rəs/ • n. (pl. same or rhinoceroses ) a large, heavily built plant-eating endangered mammal (family Rhinocerotidae) with one or two horns on the nose and thick folded skin, native to Africa and South Asia. All kinds have become endangered through hunting.

rhinoceros XIII. — L. rhīnocerōs — Gr. rhīnókerōs, f. rhī́s, rhīnó- nose + kéras HORN.
So rhinocerotic XVIII. — late L.

rhinoceros See RHINOCEROTIDAE.

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