Mammals: Rhinoceros

What's in a name?

Rhinoceroses get their name from their most famous feature: their horns. The word rhinoceros comes from the Greek rhino (nose) and ceros (horn). For ages, rhino horn has been used to treat illnesses, especially fevers. Yet like our fingernails and hair, rhino horn is made of keratin and has no healing properties. In some countries, rhinos are being dehorned, a process that removes the valuable horn but leaves the animal alive and well. This prevents poachers from killing rhinos for the money their horns would bring.

The five types of rhinos are the Sumatran, Javan, black, white, and Indian. Javan rhinos and Indian rhinos have only one horn, while Sumatran rhinos, black rhinos, and white rhinos have two. What they all have in common are large heads, broad chests, thick legs, poor eyesight, excellent hearing, and a fondness for rolling in the mud. Because they are very nearsighted, they often charge when they are startled. This has given them an undeserved reputation for having a bad temper. All rhinos are herbivores, eating grasses or leaves, depending on the species. At the San Diego Zoo's Wild Animal Park, the rhinos are fed hay and high-fiber biscuits, along with carrots and apples.

African rhinos: black and white

Black rhinos Diceros bicornis and white rhinos Ceratotherium simum are the same color—they're both brownish gray! How the white rhino came to be called “white” is uncertain. One account says that South Africa's early Boer settlers called it wijde, Dutch for “wide,” which could refer to the wide lip or the size of the animal. The wide mouth of the white rhino is perfect for grazing on grasses, while the more narrow, prehensile lip of the black rhino is great for pulling leaves and shrubs into its mouth. Other names used for these two rhinos are “broad-lipped” and "hook-lipped." Guess which name belongs to which rhino!

Meet the Asian rhinos

Indian rhinoceros Rhinoceros unicornis— The mouth of the Indian rhino looks like a cross between broad-lipped and hook-lipped. Although it is fairly broad, it has a small prehensile lip. Many people describe these rhinos as armor-plated, but they are actually covered with a layer of skin that has many folds. Also called the greater one-horned rhino, they are native to swampy areas of Northeast India and Nepal.

Javan rhinoceros Rhinoceros sondaicus— Like the Indian rhino, the Javan has a single horn. It is also called the lesser one-horned rhino. Javan rhinos are very rare in the heavily forested areas of Southeast Asia, and they are probably the rarest of the rhino species. Scientists have devised an interesting way of counting them. Throughout the rain forest, they have set up cameras with sensors. When the rhinos pass the sensor, the camera takes their picture! The scientists can then count them. Learning more about these jungle rhinos in the wild will help protect them from becoming extinct.

Sumatran rhinoceros Dicerorhinus sumatrensis— This is the smallest and hairiest of the rhinos. It is also one of the most endangered. Very little of its native habitat is left on the island of Sumatra. There has been little success in breeding this species in zoos.

Helping rhinos

The Wild Animal Park has the largest crash of rhinos and the most successful captive breeding program for rhinos anywhere in the world. When the worldwide population of southern white rhinos numbered less than 2,000, a male at the Park sired 50 babies! Many black rhinos and Indian rhinos have also been born here. In fact, one of our youngest calves is a fifth-generation Indian rhino, the first such birth in the world! We also provide support and funding for rhino conservation efforts in India.

The first black rhino born at the San Diego Zoo was named Werikhe in honor of Michael Werikhe, “the rhino man.” Mr. Werikhe was a Kenyan conservationist known for his long "rhino walks” to educate people about the plight of the rhino and to raise money to support rhino reserves. He is a good example of what one person can do to make a difference! And because all rhino species are now endangered, they need our help to survive.

Visiting the San Diego Zoo or the Wild Animal Park helps support a conservation project for the southern white rhinoceros. Although reproduction in zoos has been successful in the past, most females born in captivity have not reproduced. New research hopes to solve this mystery once and for all. To do this, researchers are taking their questions to rhino facilities around the world and to preserves with wild and semi-wild rhinos in South Africa, where they hope to find the answers they need to prevent the zoo populations from becoming extinct.