Rhinoceroses

Rhinoceros Facts

Classification:

Kingdom: Animalia

Subkingdom: Bilateria

Phylum: Chordata

Subphylum: Vertebrata

Class: Mammalia

Order: Perissodactyla

Family: Rhinocerotidae (rhinoceroses)

Genus and species:Ceratotherium cottoni (northern white rhino); C. simum (southern white rhino); Diceros bicornis (black rhino); Rhinoceros unicornis (Indian rhino), R. sondaicus (Javan rhino); Dicerorhinus sumatrensis (Sumatran rhino)

Geographical location: Africa and Asia

Habitat: Forests, grasslands, and scrub lands

Gestational period: Eight to seventeen months

Life span: Twenty to forty-five years

Special anatomy: Incisors and canine teeth in Asian species; very thick skin; one or two horns; three-toed feet

Rhinoceroses (rhinos), which are among the world’s largest land animals, belong to the ungulate family Rhinocerotidae. There are three Asian and two African species existing today; the fossil record shows several dozen extinct species as well. The animal's name comes from the Greek words, rhino and ceros, meaning “nose-horned.”

Physical Characteristics of Rhinoceroses

Rhinos weigh up to four tons and have short, thick, supportive legs. Rhino skin is thick, gray to brown in color, hangs loosely on the body, and is almost hairless. In the Asian species, skin folds at the junctures of the neck and limbs, making them look armored. The Asian species also have incisors and canine teeth, which are missing in the African species. Rhinos have long, prehensile upper lips for grasping branches and removing leaves, which they eat.

Depending on the species, rhinos have one or two nose horns. In two-horned species, the horn closest to the end of the snout is longer. The horns are made of keratin, a fibrous substance that also composes hair. The horns are used for digging food, defense, and mating combats.

Rhinos are ungulates with three toes per foot, each ending in hooflike nails. Each front foot has a vestigial fourth toe. Rhinos, which are ruminants related to horses, eat grass, bulbs, leafy twigs, and shrubs. Although they look clumsy, rhinos can run as fast as horses. They have sharp vision, very good smell, and excellent hearing. Their keen hearing is due in part to their funnel-shaped ears, which swivel in different directions.

Rhino Life Cycles

Most rhinos are both diurnal and nocturnal, active in daylight hours and after dark. They eat during the cool mornings and evenings, staying in mud wallows during hot afternoons. Rhinos have few enemies because of their size and their dangerous horns—an angry rhino charges its attackers. Humans are rhinos’ greatest enemies, killing them for their horns, which are used in jewelry or medicinally.

Most rhinos, especially males, live alone except during mating. Some exceptions exist to solitary living: mothers live with their offspring, and young males or females may form same-sex groups. Males have territories which are marked and defended. They fight each other for mates. While rhinos may not live with others of their own species, they almost always have symbiotic birds, called oxpeckers, living on and around them. The birds eat insects from the rhinos’ skins. This gives the bird food and frees the rhino from the insects.

Mating takes place year-round, and gestation lasts up to fifteen months. The female gives birth to a baby that weighs between 100 and 150 pounds. The young rhino stays with its mother for two and a half years, though it can feed itself within two and a half months. Rhinos mate at seven to ten years of age. Females wait for approximately three years between gestations, only becoming pregnant after the previous offspring has left them. Rhinos live for up to forty-five years.

Rhinoceros Species

There are five rhino species: three in Asia and Malaya and two in Africa. African rhinos are two-horned and classified as “black” or “white,” though all are bluish-gray. Black rhinos live in habitats from mountain forests to scrublands. Their maximum body length is ten feet, their height is five feet at the shoulder, and they weigh one and three quarters tons. Each has a front horn up to three and a half feet long. The rear horn is shorter.

Black rhinos are mostly nocturnal, eating in the cool morning and evening hours and wallowing in river mud during the hot daylight hours. They eat grass, leaves, herbs, fruit, branches, and twigs. In the wild, a male has a marked territory, which he defends. When the territories of several males overlap, they form groups that share resources and defend the combined territory from strangers.

White rhinos, similar to black rhinos, are the largest land mammals other than elephants. Their maximum length is thirteen feet, shoulder height is six and three quarters feet, and they weigh four tons. Females use their horns for digging, defense, and guiding their offspring. Nearly extinct, white rhinos exist only in preserves. White rhinos are divided into two species: southern and northern. As of 2023, there are only two females left. The last male died in 2018, making the species effectively extinct.

Indian rhinos—the largest Asian rhino species—average ten feet in length and five and a half feet in shoulder height and weigh two and three quarters tons. They have one thick, foot-long horn; their skin is sprinkled with knobs, and folds at the limb joints make them look like they have armor. Females, although 75 percent the weight of males have similar body heights and lengths. These rhinos live in marshy jungles and eat reeds, grass, twigs, and plant shoots. Over 4,000 Indian rhinos love in 2023, up from 1,500 Indian rhinos, all living in preserves and protected by legislation. Javan rhinos are similar to the Indian species but smaller. They occur only in Western Java, though they once lived in forests of Bengal, Burma, Borneo, Java, and Sumatra.

Sumatran rhinos, the smallest rhinos, have two horns. They are approximately four feet tallf and weigh about one ton. Unlike the smooth-skinned African rhinos, they are hairy, especially on the tail and ears. The few living Sumatran rhinos are in Sumatra’s forested hills.

Rhinoceroses are reputedly dangerous. However, they are usually peaceful and timid, except when threatened. Legally protected rhinos suffer from the market for rhino horn, reputed to be a medicine and aphrodisiac in traditional Asian medicinal practice. This market has been a major factor in driving four of the five rhino species into endangerment.

Principal Terms

Diurnal: active during the day

Keratin: a tough, fibrous substance plentiful in hair and horns

Nocturnal: active at night

Perissodactyla: ungulates having an odd number of toes

Prehensile: able to grip things

Ruminant: a herbivore that chews and swallows plants, which enter its stomach for partial digestion, are regurgitated, chewed again, and reenter the stomach for more digestion

Ungulate: a hoofed mammal

Bibliography

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“Greater One-Horned Rhino.” World Wildlife Fund, 2023, www.worldwildlife.org/species/greater-one-horned-rhino. Accessed 1 July 2023.

Karimi, Faith. “With 1 Male Left Worldwide, Northern White Rhinos under Guard 24 Hours.” CNN, 3 Mar. 2017, www.cnn.com/2015/04/16/africa/kenya-northern-white-rhino/index.html.

Morgan, James. “Here Are Our Top 10 Facts About Rhinos.” WWF, www.wwf.org.uk/learn/fascinating-facts/rhinos. Accessed 1 July 2023.

Penny, Malcolm. Black Rhino: Habitats, Life Cycle, Food Chains, Threats. Austin: Raintree Steck-Vaughn, 2001. Print.

Rasmussen, Cindy. “Are Rhinos Extinct? Discover the Conservation Status of Every Rhino Species.” AZ Animals, 6 Apr. 2023, a-z-animals.com/blog/are-rhinos-extinct-the-conservation-status-of-every-rhino-species. Accessed 1 July 2023.

“Rhinocerotidae.” ITIS, Integrated Taxonomic Information System, 8 Nov. 2017, www.itis.gov/servlet/SingleRpt/SingleRpt?search‗topic=TSN&search‗value=624916#null. Accessed 31 Jan. 2018.

Walker, Sally M. Rhinos. Minneapolis: Carolrhoda, 1996. Print.

Watt, Melanie. Black Rhinos. Austin: Raintree Steck-Vaughn, 1998. Print.