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 name of the animal comes fromGreek
rhino + 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 make them
look armored. The Asian species also have 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, for defense, and in mating combats.
Rhinos are ungulates with three toes per foot,
each of which ends 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 funnelshaped
ears, that swivel in different directions.
Rhino Life Cycles
Most rhinos are both diurnal and nocturnal, active
in daylight hours as well as 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' great enemies, killing
them for their horns, which are used in jewelry or
medicinally.
Most rhinos, especially males, live alone except
during mating. There are some exceptions 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 rhinosmaynot live with others of theirown
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 birdfood, and frees the rhino fromthe 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 mother for 2.5 years,
though it can feed itself in 2.5 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 fortyfive
years.
Rhinoceros Species
There are five rhino species: three in Asia and Malaya,
and two in Africa. African rhinos are twohorned
and classified as "black" or "white",
though all are bluish-gray. Black rhinos live in
habitats from mountain forests to scrub lands.
Their maximum body length is 10 feet, their
height is 5 feet at the shoulder, and they weigh 1.75
tons. Each has a front horn up to 3.5 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 except elephants. Their
maximum length is 13 feet, shoulder height is 6.75
feet, and they weigh 4 tons. Females use their
horns for digging, defense, and guiding their offspring.
Nearly extinct, white rhinos exist only in
preserves.
Indian rhinos-the largest Asian rhino species-
average 10 feet in length and 5.5 feet in
shoulder height, and weigh 2.75 tons. They have
one thick, foot-long horn; their skin is sprinkled
with knobs, and folds at the limb joints make them
look as though 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. There are 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 inWestern 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 4 feet tall, and
weigh about 1 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.
Classification:
Kingdom: Animalia
Subkingdom: Bilateria
Phylum: Chordata
Subphylum: Vertebrata
Class: Mammalia
Order: Perissodactyla
Family: Rhinocerotidae (rhinoceroses)
Genus and species: Ceratotherium simum (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
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