There are five extant species of odd-toed ungulates in the family Rhinocerotidae, as well as numerous extinct species in the family Rhinocerotidae. In Africa, two of the extant species are native, and three in Southern Asia.
The name “rhinoceros” is often regarded as a broader term referring to now-extinct species of the superfamily Rhinocerotoidea.
There are five extant species of odd-toed ungulates in the family Rhinocerotidae, as well as numerous extinct species in the family Rhinocerotidae. In Africa, two of the extant species are native, and three in Southern Asia. The name “rhinoceros” is often regarded as a broader term referring to now-extinct species of the superfamily Rhinocerotoidea.
Rhinoceros are among the largest remaining megafaunas, with all species being able to exceed one tonne in weight. It eats mostly plants and has a small brain (400–600 g) for mammals of its size, one or two horns, and thick (1.5–5 cm) protective skin made of collagen that links together in a lattice structure.
They generally eat leafy material, although their ability to ferment food in their hindgut allows them to subsist on more fibrous plant matter when necessary. Unlike other perissodactyls, the two African species of rhinoceros lack teeth at the front of their mouths, relying instead on their lips to pluck food.
Rhinoceros are killed by some poachers for their horns, which are bought and sold on the black market, and used by some cultures for ornaments or traditional medicine. East Asia, specifically Vietnam, is the largest market for rhino horns. By weight, rhino horns cost as much as gold on the black market.
Some cultures believe the horns to have therapeutic properties and they are ground up and the dust consumed. 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 the black, Javan, and Sumatran rhinoceros as critically endangered.
Rhinos once roamed many places throughout Europe, Asia, and Africa and were known to early Europeans who depicted them in cave paintings. At the beginning of the 20th century, 500,000 rhinos roamed Africa and Asia. By 1970, rhino numbers dropped to 70,000, and today, around 27,000 rhinos remain in the wild.
Very few rhinos survive outside national parks and reserves due to persistent poaching and habitat loss over many decades. Three species of rhino—black, Javan, and Sumatran—are critically endangered. Today, a small population of Javan rhinos is found in only one national park on the northern tip of the Indonesian island of Java.
A mainland subspecies of the Javan rhino was declared extinct in Vietnam in 2011. Successful conservation efforts have led to an increase in the number of greater one-horned (or Indian) rhinos, from around 200 at the turn of the 20th century to around 3,700 today. The greater one-horned rhino is one of Asia’s biggest success stories, with their status improving from endangered to vulnerable following significant population increases. However, the species still remains under threat from poaching for its horn and from habitat loss and degradation.
In Africa, southern white rhinos once thought to be extinct, now thrive in protected sanctuaries and are classified as near threatened. But the western black rhino and northern white rhinos have recently become extinct in the wild.
The only two remaining northern white rhino are kept under 24-hour guard in Ol Pejeta Conservancy in Kenya. Black rhinos have doubled in number over the past two decades from their low point of fewer than 2,500 individuals, but total numbers are still a fraction of the estimated 100,000 that existed in the early part of the 20th century.