Some ancient observers thought the rhinoceros was put together with rivets like an armored knight; others felt the armor could be pierced only by platinum bullets. Rhinos, as well as horses, asses, zebras and tapirs, belong to the order Perissodactyla, or odd-toed ungulates (animals which have hooves instead of claws). Within the rhinoceros family (family Rhinoce-rotidae), there are five subspecies: the African black (Diceros bicornis) and white or square-lipped (Ceratotherium simum) rhinos, the great Indian (Asian) one-horned rhino (Rhinoceros unicornis), the Javan (Rhinoceros sondaicus) and Sumatran rhinos (Dicerorhinus sumatrenis).
Rhinos in General: Several features characterize rhinos: short, stout limbs to support their massive weight; feet with three toes producing an "ace of clubs" footprint; and, of course, their horns. The horns have no bony central core; rather, they are a hoof-like aggregation of keratin fibers built upon a roughened area of the skull. Horn length varies from species to species, growing to more than 48 inches on the black rhino. Rhinos have very poor eyesight, relying upon an acute sense of smell for information about their surroundings. Reputed to be hasty, ill-tempered brutes which charge (at 35 miles per hour and capable of sharp, mid-flight turns) without provocation, rhinos actually tend to avoid confrontations. Adult male rhinos can weigh more than 7500 pounds.
The Black & White Rhinoceroses: The two African species are not really black or white; more accurate terms are the "browsing" and "grazing" rhinos. The difference lies in feeding habits. Both species have two horns.
The black rhino browses on low trees and shrubs, avoiding open grassland and dense cover in favor of the edges of small wooded areas. Using its prehensile upper lip, it can pull up seedling trees; when conditions permit, it also feeds on clover, herbs, fallen fruit, and grasses long enough to be twisted into bundles. The black rhino feeds morning and evening, resting in shade during the hottest part of the day. Since it cannot sweat, a part of its day is spent wallowing in mud and standing in open water to lower its body temperature and to keep down skin pests. Isolated black rhino populations can be found in Tanzania, Zimbabwe, Zambia, Namibia, South Africa, Kenya and other central and southeastern African countries. The estimated life span of a black rhino is 50 to 60 years. A female's pregnancy lasts about 15 months, and a newborn infant (55-85 pounds at birth) replaces older calves in the den, which can be two to five years old.
The white rhino (the world's largest land animal next to the elephant) got its name from the South African word weit, meaning wide, referring to its mouth; a better name is "grazing" rhinoceros. With a broad mouth shaped like the business end of a lawn-mower, it feeds primarily in the open grasslands of South Africa, Botswana, Zimbabwe, Namibia and other countries of southern Africa. Like the black, the white rhino feeds morning and evening, wallowing and resting during the hottest parts of the day.
Great Indian (Asian) One-Horned Rhinoceros: The Indian rhinoceros inhabits mainly swampy areas and flood plain grasslands which stretch out from riverbanks. It also lives in drier grass-lands and higher, forested country. Small, isolated populations can be found in Nepal and Pakistan. The Indian rhino once ranged extensively across the plains of the River Ganges in India. During the 19th Century, expanding human populations and hunting of rhinos for their meat, blood and horn caused the rhino population to decline sharply and contract eastwards.
The Indian rhino is a leisurely animal which spends much of its time wallowing in water holes and resting in forest shade. Evening and morning it grazes; during the afternoon, it wallows and rests. Wallowing gives the rhino a mud coating which protects it from insects, and keeps its skin supple and cool. Despite a clumsy appearance, the Indian rhino can trot quite gracefully and is a skilled swimmer.
The Indian rhinoceros enjoys a fascinating combination of solitary and communal living. While solitary male and female rhinos and females with young defend their own grazing and sleeping areas against intrusion, they also gather at communal wallowing and bathing areas. Tunnel-like paths cross the dense and grassy forest connecting water holes, bathing places and grazing areas.
Males can breed at seven to nine years old. Females are sexually mature at about three years of age and come into heat for 24 hours every five to eight weeks. After a 16-month gestation, the mother bears a calf weighing about 145 pounds. She produces a large quantity of milk which enables the calf to gain 4.5 to 6.5 pounds every day.
Javan One-Horned Rhinoceros: In 1987, an estimated 50 Javan rhinos still survived in the wild (at the western-most tip of the island of Java), making it the most critically endangered of the five species of rhinoceros. It differs from its Indian relatives in that its skin lacks the "riveted" appearance. Instead, the Javan's skin looks like a scaly mosaic, and is less rumpled in folds. This configuration gives the animal a segmented look, rather like an armadillo. Its small, single horn (about 10 inches long) appears only on males (females have a small knob at the end of their snouts).
The Javan is a browser with a prehensile lip, like its African cousin, the black rhinoceros. It lives in flatlands and in hill forests, feeding on a variety of leaves, sapling trees, twigs and even fruit. Little else is known about this species. One observation in 1985 put sexual maturity at three years for females, and at six for males. Gestation is thought to be about 16 months, with the calf remaining with its mother for about two years.
Sumatran Rhinoceros: Also called the Asian two-horned rhinoceros, the Sumatran is still found, in diminishing numbers and in isolated areas, in Burma, Indonesia and Malaysia. The smallest of the five species, it seems to be a solitary animal, congregating only to breed. Similar to the Javan and African black rhinos, it has a prehensile lip and is a browser. It "walks down" small trees in order to get at the leaves. Unlike the other rhino species, the Sumatran seems to have developed a variety of voice communications, such as snoring, braying, blowing and even humming.
Like the Javan species, not much is known about the Sumatran rhino; breeding and birth have been observed only in captivity. The density of the forest feeding areas the Sumatran prefers makes the species difficult to study. The gestation period is thought to be about 16 months. Low birth rate, the destruction of its habitat and poaching all account for its endangered species status.
Threats & Conservation: People are the only threat to adult rhinos, although the larger cats--lions and tigers--can take babies. Their downfall has been their most prominent feature--their horns. Powdered rhino horn has been in demand for many centuries as a medicine. The horn is also carved into dagger handles, primarily in Yemen.
Poaching and loss of habitat in Asia and Africa have made the rhinoceros one of the most critically endangered animals in the world. Fewer than 11,000 animals in the wild in Africa and Asia comprise the five existing rhino species.