Rhinoceros

Rhinoceros, common name for odd-toed ungulates characterized by one or two median horns on the snout. The horns are composed of a mass of agglutinated keratin, a fibrous protein found in hair; they are used mostly for digging up bulbs that, with grass and other foliage, constitute the principal food of the animal. The rhinoceros has a massive body and short, thick legs. Each foot has three functional toes covered separately with broad, hooflike nails; each forefoot also bears a nonfunctional toe. The skin is thick, gray or brown, and, in the Asian species, marked by folds at the neck and limb junctures, so that the animal seems to be covered with armor plates. The vision of rhinoceroses is poor, but this deficiency is compensated for by acute senses of smell and hearing.

Rhinoceroses are solitary animals that may also form small herds when living in grassland areas. When a female is in estrus, fighting may occur among males; the victor conducts an elaborate courtship that includes marking territory with urine and feces, chasing, fighting between the male and female, and copulation. The one offspring produced, after a gestation of 15 to 18 months, may stay with the mother for 2.5 years. When a second calf is born, the older offspring is chased away by the mother, at least temporarily.

Although the rhinoceros family was widespread in older geological times, only five species now exist: three in Asia and the Malay Archipelago, and two in tropical Africa. The former are characterized by incisors and canine teeth, both of which are lacking in the African species, as well as by the armor-plate arrangement of the skin. The Indian rhinoceros has a single horn and grows to a shoulder height of 1.7 to 1.86 m (5.5 to 6.1 ft); it is now found only in Nepal and on the plains of Assam State. The similar but smaller Javan rhinoceros, now found only in western Java, once ranged the hilly tropical forests of Bengal, Myanmar (formerly known as Burma), Borneo, Java, and Sumatra. The two-horned Sumatran rhinoceros has been widely eliminated from a similar former range.

The African black rhinoceros, a two-horned species found in savannas and on mountainsides south of Ethiopia, is characterized by a long, pointed, prehensile upper lip. Fewer than 300 African white rhinoceroses exist in eastern Africa; about 5900 still remain in South Africa. It is the largest living land mammal except for the elephant and possibly the hippopotamus, growing to a shoulder height of 1.5 to 1.85 m (4.9 to 6.1 ft) and a length of 3.35 to 4.2 m (11 to 14 ft).

Rhinoceroses, particularly the black rhino, have a reputation for being dangerous, but in general they are peaceful and even timid except when threatened; a charging rhino is then, indeed, quite dangerous. The otherwise protected rhinoceros suffers from the large market in Asia for its horn, which is used whole in artistic carving and is also prized as a medicine and aphrodisiac. Because of this market, four of the five rhinoceros species are nearing extinction.

Scientific classification: Rhinoceroses make up the family Rhinocerotidae. The Indian rhinoceros is classified as Rhinoceros unicornis, the Javan rhinoceros as Rhinoceros sondaicus, and the Sumatran rhinoceros as Dicerorhinus sumatrensis. The African black rhinoceros is classified as Diceros bicornis, and the African white rhinoceros as Ceratotherium simum.

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