By Dr. William Reville
The Irish Times
November 30, 2000
More than 200 species of mammal are distinguished by possession
of hooves, known as ungulates, and are divided into two orders,
even-toed and odd-toed ungulates. The smaller order is made up of
three families - horses, rhinoceroses and tapirs.
Rhinos have existed for over 50 million years. In the past there
were many different kinds of rhinos, roaming North America, Europe,
Africa and Asia, including the largest land mammal that ever lived.
Today, five species of rhino survive, but all are on the verge
of extinction. It would be a catastrophic loss if such a venerable
group of animals were to vanish from the world.
The rhinoceros is a large, ponderous, hoofed, primitive-looking
mammal, found today in eastern and southern Africa and tropical
Asia. They have massive bodies, large heads, three digits on both
front and hind feet and thickly folded skin that forms plate-like
folds resembling armour, especially at shoulders and thighs.
All rhinos are grey or brown in colour and most are nearly hairless.
Rhinos may grow to 14 feet long and 6.5 feet high at shoulder. Adults
may weigh up to four tons and the huge body rests on four short
The name rhinoceros means "nose horn". Some species have
one large horn curving upwards from the snout, while other species
have two horns. The horn grows from the skin, is hard, and is made
from a solid mass of hairs. Like hair, the horn grows as much as
three inches per year. The longest known horn was over five feet
Two species of rhino live in Africa: the black rhinoceros and the
white, or square-lipped, rhinoceros (both animals are grey). Both
animals have two horns. Next to the elephant, the white rhinoceros
ranks with the hippopotamus as the largest living land mammal. White
rhinos live on grassy plains in herds of about 10 animals. The males
fight a lot during the breeding season.
The black rhino is smaller than the white and adults live alone
in dry inland areas along the coast and in the mountains. Rhinos
are vegetarian. The white rhino grazes on dense, short green grass.
The black rhino browses on trees and shrubs. Rhinos are generally
promiscuous, rarely forming even semi-permanent pairings.
The other three species of rhino (Indian, Javan and Sumatran) live
in Asia. Two species are one-horned (Indian, Javan) and the other
is two-horned (Sumatran). The one-horned species lives in swampy
jungles. The Sumatran rhino is the smallest and, unlike other species,
it is hairy.
Rhinos have small eyes and are short-sighted, but their senses
of hearing and smell are keen. They prefer to avoid humans, but
males, particularly during the breeding season, and females with
calves, may charge with very little provocation. They can run at
speeds of up to 28 miles per hour for short distances and will gouge
with their horns if they make contact. For all its bulk, the rhino
is very agile and can turn quickly in a small space.
Rhinos use many sounds to communicate. They snort, snarl and roar,
and, when fighting, they grunt and scream. Both males and females
whistle when courting.
The female rhino (cow) bears a single calf every three or four
years. The gestation period is 18 months and the calf weighs up
to 100lbs. The calves are frisky and playful, and the cow comforts
them with soft mewing noises.
The cow is fiercely defensive of the calf against predators such
as crocodiles, lions and hyenas. As the older calves mature, they
leave their mothers and may join other females and their young where
they are tolerated for a while before departing to live independently.
The African White rhino has a symbiotic (mutually dependent) relationship
with red-billed ox-peckers, also called tick birds. In Swahili,
the tick bird is named "askari wa kifaru", which means
"the rhino's guard". The bird eats ticks that are present
on the rhino and also noisily warns the rhino of danger. Although
the birds also eat blood from sores on the rhino's skin and thereby
obstruct healing, they are still tolerated.
All species of rhino are threatened and some are very close to
extinction. The Sumatran rhino has been exterminated in much of
its range and only 400 remain. About 2,400 Indian rhino, about 10,400
White rhino, and about 2,700 Black rhino survive. The Javan rhino
is one of the world's most critically endangered species, and only
about 60 survive.
The above figures (14,000 in total) refer to rhinos surviving in
the wild. In addition, about 1,000 rhinos are held in captivity
IN the wild the adult rhino has no true natural predator. Man is
the cause of the demise of the rhino. Despite the rhino's size and
aggressive reputation, it is still very easy for hunters to kill
the animal. They are creatures of habit, live in a well-defined
home range and usually visit the water-hole daily where they are
Despite protective laws, they continue to be hunted. Nearly all
parts of the rhino are used in traditional folk medicine in Asia
and the horn is valued as a knife handle in the Middle East. Many
East Asian peoples believe that the rhino horn is a powerful aphrodisiac.
Most rhinos are hunted primarily for their horns. It is a particular
shame to kill a great creature in order to harvest a single organ
deemed desirable to humans. Apart from the rhino, elephants are
killed for their tusks, buffaloes for their tongues, and gorillas
because some people want to buy ashtrays made out of large primate
Urgent efforts are under way to save the rhino from extinction.
The Black rhino population declined greatly due to poaching in the
1970s and 1980s. Many rhinos were moved to fenced sanctuaries in
the early 1990s, an effort that seems to be succeeding. In 1994
rhino numbers did not decline for the first time in 20 years.
William Reville is a senior lecturer and director of microscopy