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.
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 61/2 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 41/2 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.
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.
The rhinoceros is classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Perissodactyla, family Rhinocerotidae.
See M. Penny, Rhino (1988); S. Fitzgerald, International Wildlife Trade (1989); F. B. Salvadori, Rare Animals of the World (1990).
The rhinoceros family is characterised by large size (one of the largest remaining megafauna alive today) with all of the species capable of reaching 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 dental formula varies greatly between species, but in general is:
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.
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. 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.
The White Rhino has a massive 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.
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.
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.
The Indian Rhinoceros or the Great One-horned Rhinoceros (Rhinoceros unicornis) is found in Nepal and in Assam, India. It is also known as Gaida in Nepali. The rhino once inhabited areas from 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 and Nepal. 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 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.
A big bastion of one horn or Indian rhino is the Kaziranga National Park situated in the Golaghat district of Assam, India
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.
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.
Hyracodontidae, also known as "running rhinos," showed adaptations for speed, and would have looked more like horses than modern rhinos. The smallest hyracodontids were dog-sized; the largest was Indricotherium, believed to be one of the largest land mammals that ever existed. The hornless Indricotherium was almost seven meters high, ten meters long, and weighed as much as 15 tons. Like a giraffe, it ate leaves from trees. The Hyracodontids spread across Eurasia from the mid-Eocene to early Miocene.
The family Amynodontidae, also known as "aquatic rhinos," dispersed across North America and Eurasia, from the late Eocene to early Oligocene. The amynodontids were hippopotamus-like in their ecology and appearance, inhabiting rivers and lakes, and sharing many of the same adaptations to aquatic life as hippos.
The family of all the modern rhinoceroses, the Rhinocerotidae, first appeared in the Late Eocene in Eurasia. The earliest members of Rhinocerotidae were small and numerous; at least 26 genera lived in Eurasia and North America until a wave of extinctions in the middle Oligocene wiped out most of the smaller species. Several independent lineages survived, however. Menoceras, a pig-sized rhinoceros which had two horns side-by-side or the Teleoceras of North America which had short legs and a barrel chest and lived until about 5 million years ago. The last rhinos in America became extinct during the pliocene.
Modern rhinos are believed to have dispersed from Asia beginning in the Miocene. Two species survived the most recent period of glaciation and inhabited Europe as recently as 10,000 years ago. The Woolly Rhinoceros appeared in China around 1 million years ago and first arrived in Europe around 600,000 years ago and again 200,000 years ago, where alongside the Woolly Mammoth, they became numerous but eventually were hunted to extinction by early humans. Another species of enormous rhino, Elasmotherium, survived the last ice age. Also known as the giant Rhinoceros rhinoceros, Elasmotherium was two meters tall, five meters long and weighed around five tons, with a single enormous horn, hypsodont teeth and long legs for running.
Of the extant rhinoceros species, the Sumatran Rhino is the most archaic, first emerging more than 15 million years ago. The Sumatran Rhino was closely related to the Woolly Rhinoceros, but not to the other modern species. The Indian Rhino and Javan Rhino are closely related and from a more recent lineage of Asian rhino. The ancestors of early Indian and Javan rhino emerged 2-4 million years ago.
The origin of the two living African rhinos can be traced back to the late Miocene species Ceratotherium neumayri. The lineages containing the living species diverged by the early Pliocene when Diceros praecox, the likely ancestor of the Black Rhinoceros, appears in the fossil record. The black and white rhinoceros remain so closely related that they can still mate and successfully produce offspring.
One repeated misconception is that rhinoceros horn in powdered form is used as an aphrodisiac in Traditional Chinese Medicine. It is, in fact, prescribed for fevers and convulsions. Discussions with TCM practitioners to reduce its use have met with mixed results since some TCM doctors 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, which needs to be carefully managed.
There are a number of legends about rhinoceroses stamping out fire. The story seems to have been common in Malaysia, India, and Burma. This type of rhinoceros even had a special name in Malay, badak api, where badak means rhinoceros and api means fire. The animal would come when a fire is lit in the forest and stamp it out. Whether or not there is any truth to this has not yet been proven, as there has been no documented sighting of this phenomenon in recent history. This lack of evidence may stem from the fact that rhinoceros sightings overall in south-east Asia have become very rare, largely owing to widespread poaching of the critically endangered animal. This legend is featured prominently in the film The Gods Must Be Crazy as well as on an episode of The Simpsons.
In The Chronicles of Narnia: The Lion, the Witch, and the Wardrobe, five black rhinoceros are seen fighting against the White Witch.
In U.S. military aviation, one of the unofficial names for the McDonnell Douglas F-4 Phantom II fighter was "Rhino" and the Boeing (McDonnell Douglas) F/A-18 E/F Super Hornet carrier-based strike fighter for the U.S. Navy is also unofficially known as the "Rhino" to distinguish it from the legacy F/A-18 Hornet models when calling the ball in the carrier landing pattern so that the proper weight for the arresting gear can be set without a confusion between "Hornet" and "Super Hornet" over the radio, should the transmission be garbled.
In the One Thousand and One Nights tales, a rhino is described fighting with an elephant. "The rhinoceros fights with the elephant, and transfixing him with his horn carries him off upon his head, but becoming blinded with the blood of his enemy, he falls helpless to the ground, and then comes the roc, and clutches them both up in his talons and takes them to feed his young."