A rhinoceros (/raɪˈnɒsərəs/, meaning "nose horn"), often abbreviated
to rhino, is one of any five extant species of odd-toed ungulatesin the family Rhinocerotidae, as well as any of the numerous extinct species. Two of
these extant species are native to Africa and
three to Southern
Asia.
Members of the rhinoceros family are characterized by
their large size (they are some of the largest remaining megafauna, with all of the species able to reach one tonne or
more in weight); as well as by an herbivorous diet; a thick protective skin, 1.5–5 cm thick,
formed from layers of collagen positioned in a lattice structure; relatively small brains for mammals this
size (400–600 g); and a large horn. They generally eat leafy material,
although their ability to ferment food in their hindgut allows them to subsist on more fibrous plant
matter, if 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 humans for their horns, which
are bought and sold on the black market, and which are used by some cultures for ornamental
or traditional
medicinal purposes. East Asia,
specifically Vietnam, is the largest market for rhino horns. By weight, rhino
horns cost as much as gold on the black market. People grind up the horns and
then consume them believing the dust has therapeutic properties. 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 three of the species as critically
endangered.
The word rhinoceros is derived through Latin from the Ancient Greek: ῥῑνόκερως, which is
composed of ῥῑνο- (rhino-, "nose") and κέρας(keras, "horn"). The plural in English is rhinoceros or rhinoceroses. The collective
noun for a group of
rhinoceroses is crash or herd. The name has been in use since the 14th
century.
The family Rhinocerotidae consists of only four extant
genera: Ceratotherium (White
rhinoceros), Dicerorhinus (Sumatran
rhinoceros), Diceros (Black
rhinoceros) and Rhinoceros (Indian and
Javan rhinoceros). The living species fall into three categories. The two
African species, the white rhinoceros and the black rhinoceros, belong to the tribe Dicerotini, which originated in the
middle Miocene, about 14.2 million years ago. The species diverged
during the early Pliocene (about 5 million years ago). The main difference
between black and white rhinos is the shape of their mouths – white rhinos have
broad flat lips for grazing, whereas black rhinos have long pointed lips for
eating foliage. There are two living Rhinocerotini species, the Indian rhinoceros and the Javan rhinoceros, which diverged from one another about 10 million years
ago. The Sumatran
rhinoceros is the only surviving
representative of the most primitive group, the Dicerorhinini, which emerged in
the Miocene (about 20 million years ago).
A subspecific hybrid white rhino (Ceratotherium s. simum × C. s. cottoni) was bred at
the Dvůr Králové
Zoo (Zoological Garden Dvur Kralove nad
Labem) in the Czech
Republic in 1977. Interspecific
hybridisation of black and white
rhinoceros has also been confirmed.
While the black rhinoceros has 84 chromosomes (diploid number, 2N, per cell), all other
rhinoceros species have 82 chromosomes. However, chromosomal
polymorphism might lead to varying
chromosome counts. For instance, in a study there were three northern white
rhinoceroses with 81 chromosomes.
Characteristics
White rhinoceros
Main article: White rhinoceros
There are two subspecies of white rhinoceros: the southern white
rhinoceros (Ceratotherium simum simum)
and the northern white
rhinoceros(Ceratotherium simum cottoni).
As of 2013, the southern subspecies has a wild population of 20,405 – making
them the most abundant rhino subspecies in the world. However, the northern
subspecies is critically endangered, with as few as three known individuals
left in captivity. There is no conclusive explanation of the name white
rhinoceros. A popular theory that "white" is a distortion of either
the Afrikaans word wyd or the Dutch word wijd (or its other possible spellings whyde, weit,
etc.,) meaning wide and referring to the rhino's square lips is not supported
by linguistic studies.
The white rhino has an immense body and large head, a
short neck and broad chest. Females weigh 1,600 kg (4,000 lb) and
males 2,400 kg (5,000 lb). The head-and-body length is 3.5–4.6 m
(11–15 ft) and the shoulder height is 1.8–2 m (5.9–6.6 ft). On
its snout it has two horns. The front horn is larger than the other horn and
averages 90 cm (35 in) in length and can reach 150 cm
(59 in). The white rhinoceros also has a prominent muscular hump that
supports its relatively large head. The colour of this animal can range from
yellowish brown to slate grey. Most of its body hair is found on the ear
fringes and tail bristles, with the rest distributed rather sparsely over the
rest of the body. White rhinos have the distinctive flat broad mouth that is
used for grazing.
Black rhinoceros
Main article: Black rhinoceros
The name "black rhinoceros" (Diceros bicornis) was chosen to
distinguish this species from the white rhinoceros (Ceratotherium simum). This can be confusing, as the two species are not truly
distinguishable by color. There are four subspecies of black rhino:
South-central (Diceros bicornis minor), the most numerous, which once ranged from
central Tanzania south through Zambia, Zimbabwe and Mozambique to northern and eastern South Africa; South-western (Diceros bicornis occidentalis) which are better adapted to the arid and semi-arid
savannas of Namibia, southern Angola,
western Botswana and western South Africa; East African (Diceros bicornis michaeli), primarily in Tanzania; and West African (Diceros bicornis longipes) which was declared extinct in November 2011. The
native Tswanan name keitloa describes a
South African variation of the black rhino in which the posterior horn is equal
to or longer than the anterior horn.
An adult black rhinoceros stands 1.50–1.75 m
(59–69 in) high at the shoulder and is 3.5–3.9 m (11–13 ft) in
length. An adult weighs from 850 to 1,600 kg (1,870 to
3,530 lb), exceptionally to 1,800 kg (4,000 lb), with the
females being smaller than the males. Two horns on the skull are made of keratin with the larger front horn typically 50 cm long,
exceptionally up to 140 cm. Sometimes, a third smaller horn may
develop. The black rhino is much smaller than the white rhino, and has a pointed mouth, which it uses to grasp leaves
and twigs when feeding.
During
the latter half of the 20th century, their numbers were severely reduced from
an estimated 70,000 in the late 1960s to a record low of 2,410 in 1995.
Since then, numbers have been steadily increasing at a continental level with
numbers doubling to 4,880 by the end of 2010. Current numbers are however still
90% lower than three generations ago.
Indian rhinoceros
Main article: Indian rhinoceros
The Indian rhinoceros, or greater one-horned rhinoceros,
(Rhinoceros unicornis) has a single horn 20 to 60 cm long. It is nearly as large
as the African white rhino. Its thick, silver-brown skin forms huge folds all
over its body. Its upper legs and shoulders are covered in wart-like
bumps, and it has very little body hair. Grown males are larger than females in
the wild, weighing from 2,500–3,200 kg (5,500–7,100 lb). Shoulder
height is 1.75–2.0 m (5.7–6.6 ft). Females weigh about 1,900 kg
(4,200 lb) and are 3–4 m (9.8–13 ft) long. The record-sized
specimen was approximately 3,800 kg (8,400 lb).
Indian rhinos once inhabited many areas ranging
from Pakistan to Burma and
maybe even parts of China. However, because of human influence, they now only
exist in several protected areas of India (in Assam, West Bengal, and a few pairs in Uttar Pradesh) and Nepal,
plus a few pairs in Lal Suhanra
National Park in Pakistan. It is confined
to the tall grasslands and forests in the foothills of the Himalayas. Two-thirds of the world's Indian rhinoceroses are now confined to the Kaziranga National
Park situated in the Golaghat district of Assam,
India.
Javan rhinoceros
Main article: Javan rhinoceros
The Javan rhinoceros (Rhinoceros sondaicus)
is one of the most endangered large mammals in
the world. According to 2015 estimates, only about 60 remain, in Java,
Indonesia, all in the wild. It is also the least known rhino species. Like the
closely related, and larger, Indian rhinoceros, the Javan rhino has a single horn. Its hairless, hazy
gray skin falls into folds into the shoulder, back, and rump, giving it an
armored appearance. Its length reaches 3.1–3.2 m (10–10 ft) including
the head, and its height 1.5–1.7 m (4 ft 11 in–5 ft
7 in). Adults are variously reported to weigh 900–1,400 kg or
1,360–2,000 kg. Male horns can reach 26 cm in length, while in
females they are knobs or altogether absent. These animals prefer dense
lowland rain forest, tall grass and reed beds that are plentiful with large
floodplains and mud wallows.
Though once widespread throughout Asia, by the 1930s they
were nearly hunted to extinction in Nepal, India, Burma, Peninsular Malaysia, and Sumatra for the supposed medical powers of their horns and blood. As of
2015, only 58-61 individuals remain in Ujung Kulon
National Park, Java, Indonesia. The last rhino
in Vietnam was reportedly killed in 2011.
Sumatran rhinoceros
Main article: Sumatran rhinoceros
The Sumatran rhinoceros (Dicerorhinus sumatrensis)
is the smallest extant rhinoceros species, as well as the one with the
most hair. It can be found at very high altitudes in Borneoand Sumatra. Due to habitat loss and poaching, their numbers have declined and it has become the most
threatened rhinoceros. About 275 Sumatran rhinos are believed to remain. There
are three subspecies of Sumatran rhinoceros: the Western
Sumatran rhinoceros (Dicerorhinus sumatrensis sumatrensis), Eastern
Sumatran rhinoceros (Dicerorhinus sumatrensis harrissoni) and the extinct Northern
Sumatran rhinoceros (Dicerorhinus sumatrensis lasiotis).
A mature rhino typically stands about 1.3 m
(4 ft 3 in) high at the shoulder, has a length of 2.4–3.2 m
(7 ft 10 in–10 ft 6 in) and weighs around 700 kg
(1,500 lb), though the largest individuals have been known to weigh as
much as 1,000 kilograms. Like the African species,
it has two horns; the larger is the front (25–79 cm), with the smaller
usually less than 10 cm long. Males have much larger horns than the
females. Hair can range from dense (the densest hair in young calves) to
sparse. The color of these rhinos is reddish brown. The body is short and has
stubby legs. The lip is prehensile.
Sumatran rhinoceros are on the verge of extinction due to
loss of habitat and illegal hunting. Once they were spread across South-east
Asia, but now they are confined to several parts of Indonesia and Malaysia due
to reproductive isolation. There were 320 of D. sumatrensis in 1995, which by 2011 have dwindled to 216. It has
been found through DNA comparison that the Sumatran rhinoceros is the most
ancient extant rhinoceros, and related to the extinct Woolly Rhinoceros, Coelodonta. In 1994 Alan Rabinowitz publicly denounced that governments, NGOs and other
institutions were lacking in attempts to conserve the Sumatran rhinoceros. In
order to conserve it, they would have to be relocated from small forests to
breeding programs where their breeding success could be monitored. In order to
boost reproduction, the Malaysian and Indonesian governments could also agree
on exchanging the gametes of the Sumatran and (smaller) Bornean subspecies.
There has also been a proposal by the Indonesian and Malaysian governments for
a single management unit for these two ancient subspecies.
Plantations
for palm oil have taken out the living areas and led to the eradication of the
rhino in Sumatra.
Evolution
Rhinocerotoids diverged from other perissodactyls by the
early Eocene. Fossils of Hyrachyus
eximus found in North America date
to this period. This small hornless ancestor resembled a tapir or
small horse more than a rhino. Three families, sometimes
grouped together as the superfamily Rhinocerotoidea, evolved in the late Eocene, namely
the Hyracodontidae, Amynodontidae and Rhinocerotidae.
Hyracodontidae
Main article: Hyracodontidae
Hyracodontidae, also known as 'running rhinos', showed
adaptations for speed, and would have looked more like horses than modern
rhinos. The smallest hyracodontids were dog-sized; the largest was Indricotherium, believed to be
one of the largest land mammals that ever existed. The hornless Indricotherium was almost seven metres high, ten metres long, and
weighed as much as 15 tons. Like a giraffe, it ate leaves from trees. The
hyracodontids spread across Eurasia from the mid-Eocene to early Miocene.
Amynodontidae
Main article: Amynodontidae
The Amynodontidae, also known as "aquatic
rhinos", dispersed across North America and Eurasia, from the late Eocene to
early Oligocene. The amynodontids were hippopotamus-like in their ecology and appearance, inhabiting rivers
and lakes, and sharing many of the same adaptations to aquatic life as hippos.
Rhinocerotidae
The family of all modern rhinoceros, the Rhinocerotidae,
first appeared in the Late Eocene in Eurasia. The earliest members of
Rhinocerotidae were small and numerous; at least 26 genera lived in Eurasia and
North America until a wave of extinctions in the middle Oligocene wiped out
most of the smaller species. However, several independent lineages
survived. Menoceras, a
pig-sized rhinoceros, had two horns side-by-side. The North American Teleoceras had short legs, a barrel chest and lived until
about 5 million years ago. The last rhinos in the Americas became extinct
during the Pliocene.
Modern rhinos are thought to have begun dispersal
from Asia during the Miocene. Two species survived the most recent period of glaciation and
inhabited Europe as recently as 10,000 years ago: the woolly rhinoceros and Elasmotherium. The woolly
rhinoceros appeared in China around 1 million years ago and first arrived in
Europe around 600,000 years ago. It reappeared 200,000 years ago, alongside
the woolly
mammoth, and became numerous. Elasmotherium was
two meters tall, five meters long and weighed around five tons, with a single
enormous horn, hypsodont teeth and long legs for running. Both the Coelodonta
and Elasmotherium survived through the late Pleistocene when climate fluctuations, increased predation by
newer predators such as Hyenas and
human hunting lead to their extinction. There may have been a remnant
population of Elasmotherium, however, in the south of Western Siberia (the area that is today Kazakhstan) as recently as 29,000 years ago.
Of the extant rhinoceros species, the Sumatran rhino is the most archaic, first emerging more than 15
million years ago. The Sumatran rhino was closely related to the woolly
rhinoceros, but not to the other modern species. The Indian rhino and Javan rhino are closely related and form a more recent lineage
of Asian rhino. The ancestors of early Indian and Javan rhino diverged 2–4
million years ago.
The origin of the two living African rhinos can be traced
to the late Miocene (6 mya) species Ceratotherium neumayri. The
lineages containing the living species diverged by the early Pliocene (1.5 mya), when Diceros praecox, the
likely ancestor of the black rhinoceros, appears in the fossil record. The
black and white rhinoceros remain so closely related that they can still mate
and successfully produce offspring.
Adult rhinoceros have no real predators
in the wild, other than humans. Young rhinos can however fall prey to big
cats, crocodiles, wild
dogs, and hyenas.
Although rhinos are large and have a
reputation for being tough, they are very easily poached; they visit water
holes daily and can be easily killed while they drink. As of December 2009,
poaching increased globally while efforts to protect the rhino are considered
increasingly ineffective. The most serious estimate, that only 3% of poachers
are successfully countered, is reported of Zimbabwe, while Nepal has largely avoided the crisis.
Poachers have become more sophisticated. South African officials have called
for urgent action against poaching after poachers killed the last female rhino
in the Krugersdorp Game Reserve near Johannesburg. Statistics from South African National Parks show that 333 rhinoceros were
killed in South Africa in 2010, increasing to 668 by 2012, over 1,004
in 2013. and over 1,338 killed in 2015. In some cases rhinos are
drugged and their horns removed, while in other instances more than the horn is
taken.
The Namibian government and Save the Rhino International have been positive about the benefits that rhino trophy
hunting may hold for conservation. Hunting licenses for five Namibian Black
rhinos are auctioned annually. Additionally, support for a legal trade of rhino
horn to combat poaching has been growing. Some conservationists and
members of the public however oppose or question this practice.
Horn trade and use
Rhinoceros horns, unlike those of other
horned mammals (which have a bony core), only consist of keratin, similar to human hair and nails.
Rhinoceros horns are used in traditional medicines in parts of Asia, and for dagger
handles in Yemen and Oman. Esmond Bradley Martin has reported on the trade for
dagger handles in Yemen. In Europe, it was historically believed that rhino horns could
purify water and could detect poisoned liquids, and likely as an aphrodisiac and an antidote to poison.
Contrary to popular belief, the market
for rhino horn is not largely driven by Chinese. Rather, Vietnamese are
currently the biggest consumers of rhino horn and Vietnamese demand drives most
of the poaching which has shot up to record levels. In Vietnam, the
powdered horn is inhaled by some of the wealthy as a status symbol, where rhino
horn is believed by some to have aphrodisiac properties. The "Vietnam
CITES Management Authority" has claimed that Hanoi recently experienced a
77% drop in the usage of rhino horn, but National Geographic has challenged
these claims, noticing that there was no rise in the numbers of criminals who
were apprehended or prosecuted. South African rhino poaching's main
destination market is Vietnam.
It is a common misconception that rhinoceros
horn in powdered form is used as an aphrodisiac or a cure for cancer in Traditional Chinese
Medicineas Cornu Rhinoceri Asiatici (犀角, xījiǎo, "rhinoceros horn"); no TCM text in
history has ever mentioned such prescriptions. Western media has falsely
propagated this idea for a long time and the Vietnamese received the idea
that rhino horn was an aphrodisiac from the western media's false
reporting. In Traditional Chinese
Medicine (TCM), rhino horn is considered an effective medicine
sometimes prescribed for fevers and convulsions, a treatment not supported
by evidence-based medicine and
has been compared to consuming fingernail clippings in water. In 1993,
China signed the CITES treaty
and removed rhinoceros horn from the Chinese medicine
pharmacopeia, administered by the Ministry of Health. In 2011, the
Register of Chinese Herbal Medicine in the United Kingdom issued
a formal statement condemning the use of rhinoceros horn. A growing number
of TCM educators is also speaking out against the practice. Discussions
with TCM practitioners to reduce the use of rhino horn, has met with mixed
results, because some still consider it a life-saving medicine of a better
quality than its substitutes.
In March 2013, some researchers
suggested that the only way to reduce poaching would be to establish a regulated trade based on humane and renewable harvesting from live
rhinos. The WWF however opposes legalization of the horn trade, as it may increase
demand, while IFAW released a report by EcoLarge, suggesting that more thorough knowledge of economic factors
is required in order to justify the pro-trade option. The South African
government has supported the establishment of a legal trade of rhino horn
stating that at the 17th Meeting of Conference of the Parties to CITES (CoP17)
in 2016 they will apply for a legal trade in Rhino Horn in an attempt to reduce
poaching and prevent the extinction of this species.
To prevent poaching, in certain areas, rhinos have
been tranquillized and their horns removed. Armed park rangers, particularly in
South Africa, are also working on the front lines to combat poaching, sometimes
killing poachers who are caught in the act. A recent spike in rhino killings
has made conservationists concerned about the future of the species. An
average sized horn can bring in as much as a quarter of a million dollars in
Vietnam and many rhino range states have stockpiles of rhino horn.
In 2011 the Rhino Rescue Project,
organized by Ed and Lorinda Hern of the Rhino & Lion Nature Reserve in
Krugersdorp, South Africa, began a horn-trade control method consisting of
infusing the horns (while on the animal) with a mixture of a pink dye and
an acaricide (to kill ticks) which is safe for rhinos but toxic to
humans. After sedating the animal, holes are drilled into the horns,
fittings added, and the cavity connected with rubber hoses to a
two-foot-by-four-inch diameter metal container of the liquid mixture which is
then pressurized. The infusion takes less than 20 minutes of the 45
minutes of anesthesia; because of the high pressure exerted on the animals'
internal organs from their large body weight, they are turned every 7 minutes
while sedated. The procedure also includes inserting three RFID identification chips and taking
DNA samples.
Because of the fibrous nature of rhino
horn, the pressurized dye infuses the interior of the horn but does not color
the surface or affect rhino behavior. The acaricide is expected to cause
nausea, stomach-ache and diarrhea, or convulsions for anyone consuming the
horn, depending on the quantity, but would not be fatal; the primary deterrent
being the knowledge that the treatment has been applied, communicated by signs
posted at the refuges. The original idea grew out of research looking into
using the horn as a reservoir for one-time tick treatments, and the acaricide
is selected to be safe for the rhino, oxpeckers, vultures, and other animals in the preserve's
ecosystem. It was claimed that the dye can not be successfully removed
from horns, and would remain visible on x-ray scanners even when the horn is
ground to a fine powder.
The UK charity organization Save the Rhino has
criticized horn poisoning on moral and practical grounds. The organization
questions the assumptions that the infusion technique works as intended, and
that even if the poison were effective, whether middlemen in a lucrative,
illegal trade would care much about the effect it would have on buyers on
another continent. They also claim that poisoned horns could heighten
demand for non-poisoned horns among wealthier buyers or could fuel the belief
in magical properties of the horn if people survive the
poisoning. Additionally, rhino horn is increasingly purchased for
decorative use, rather than for use in traditional medicine. Save the Rhino
questions the feasibility of applying the technique to all African rhinos,
since the acaricide would have to be reapplied every 4 years. It was
also reported that one out of 150 rhinos treated did not survive the
anesthesia.
The only remaining Javan rhino in Vietnam was
slaughtered in 2011 by Vietnamese poachers in order to obtain its
horn. Now only Java contains the last Javan rhinos.
Rhino horn from South Africa was acquired by the North
Korean diplomat Park Chol-jun.
Historical representations
Albrecht Dürer created a famous woodcut of a rhinoceros in 1515, based on
a written description and brief sketch by an unknown artist of an Indian
rhinoceros that had arrived in Lisbon earlier that year. Dürer never saw
the animal itself and, as a result, Dürer's Rhinoceros is a somewhat inaccurate depiction. Rhinoceros are
depicted in the Chauvet Cave in France, pictures dated to 10,000-30,000 years ago.
Greek historian and geographer Agatharchides (2nd
century BC) mentions the rhinoceros in his book On the Erythraean Sea.
There are legends about rhinoceroses
stamping out fire in Burma, India, and Malaysia. The mythical rhinoceros has a special name in Malay, badak api, wherein badak means rhinoceros, and api means fire. The animal would come
when a fire was lit in the forest and stamp it out. There are no recent
confirmations of this phenomenon. However, this legend has been reinforced by
the film The Gods Must Be Crazy (1980), wherein an African
rhinoceros is shown to be putting out two campfires