Rhinoceros

Rhinoceros are the family of Rhinocerotidaes which are also called rhinoceros, rhinoceroses, or rhinoceri. They are any of five or six species of giant horn-bearing herbivores, which include a few of the largest living land mammals. Only Asian and African elephants are taller at the shoulder than the two largest rhinoceros species, which are the white, or square-lipped, rhinoceros (or Ceratotherium simum), which a few divide into two species (southern white rhinoceros (C. simum) and (northern white rhinoceros (C. cottoni), and the Indian, or the greater one-horned, rhinoceros (also called Rhinoceros unicornis).

Types of Rhinoceros Mammal and their Characteristics

Let us look at more about rhinoceros and types of rhinoceros in brief.

The white and the black rhinoceros mammal or rhinoceros black (also called Diceros bicornis) live in Africa, while the Javan rhinoceros (R. sondaicus), the Indian rhinoceros, and the Sumatran rhinoceros mammal (Dicerorhinus sumatrensis) live in Asia. The precarious state of surviving species (all but one are endangered) is in direct contrast to the early history of this particular group as one of the most successful lineages of the hoofed mammals. Now, the total population of the entire rhinoceros species combined is probably fewer than 30,000. Today, rhinoceroses are restricted to southern and eastern Africa and to subtropical and tropical Asia.

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Rhinoceroses can be characterized by the possession of either one or two horns on the upper surface of the snout; these specific horns are not true horns, but they are composed of keratin, which is a fibrous protein found in hair. Modern rhinoceroses are defined as large animals, ranging from 2.5 metres (8 ft) long, 1.5 metres (5 ft) high at the shoulder in the Sumatran biggest rhinoceros to up to 4 metres (13 ft) long and approximately 2 metres (7 ft) high in the white rhinoceros.

The adults of larger species weigh about 3–5 tons. Rhinoceroses are most noted for their thick skin that forms platelike folds, especially at the thighs and shoulders. All rhinos are either gray or brown in color, including the white biggest rhinoceros that tend to be paler compared to others. Aside from the Sumatran rhinoceros, they are up to or completely hairless, except for the ear fringes and tail tip, but a few fossil species were covered with the dense fur. The feet of the modern species contain three short toes, tipped with blunt nails and broad.

The Northern white rhinoceros mammal (which are called Ceratotherium simum cottoni) grazing at the Laikipia, Ol Pejeta Conservancy, Kenya, is figured below. As of December 2014, only 5 northern white rhinoceroses remained worldwide.

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Rhinoceroses contain poor eyesight but acute senses of smell and hearing. Most of them prefer to avoid humans, but females and males, with calves, may charge with little provocation. The black rhinoceros (also called Diceros bicornis) is generally unpredictable and ill-tempered and may charge any unfamiliar smell or sound. Despite their bulk, rhinoceroses are very remarkably agile; the black rhinoceros may attain a speed of up to 45 km (30 miles) per hour, even in thick brush, and may turn around rapidly after missing the charge.

Like elephants, rhinoceroses will communicate using infrasonic frequencies, which are below the threshold of human hearing. The infrasonic frequency use is likely an adaptation for rhinoceroses to keep in touch with each other where they usually inhabit dense vegetation and probably for females to advertise to males when females tend to be receptive to breeding.

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By far, rhinoceroses are the largest of the perissodactyls, which are an order of hoofed mammals, which also include zebras and horses. One of the features of very large body size in mammals is given a low reproductive rate. In rhinoceroses, the females do not conceive until up to six years of age; gestation is long (16 months in most of the species), and they give birth to only one calf at one time.

The birth period between calves may range from 2 to 4.5 years. Therefore, the loss of a number of breeding-age females to poachers may greatly slow the rhinoceros population recovery. However, an Indian rhinoceros female will again quickly conceive if she loses the calf. In this species, tigers kill up to 10–20% of calves. Tigers rarely kill calves that are older than 1 year, so those Indian rhinoceroses, which survive past that point, are invulnerable to non-human predators.

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The three Asian species fight with their razor-sharp lower outer incisor teeth but not with their horns. In Indian rhinoceroses, such tusks or teeth can reach 13 cm (5 inches) in length among the dominant males and inflict lethal wounds on the other males competing for access to breeding females. In contrast, the African species lack these long tusklike incisors and instead, they will fight with their horns.

The horn of the rhinoceros is also the cause of its demise. Powdered rhinoceros horn has been a sought commodity in traditional Chinese medicine - not as an aphrodisiac, as it is often widely reported, but as an anti-fever agent. Substitute agents have been found, specifically water buffalo and pig bone horn, but rhinoceros horn commands tens of thousands of dollars per one kilogram in Asian markets. Nowadays, poaching remains a serious problem throughout the range of the entire species of rhinoceros.

The term rhinoceros is at times also applied to the other, extinct members of the family Rhinocerotidae, which is a diverse group that includes many dozen fossil genera, among them the woolly rhinoceros (or Coelodonta antiquitatis). Early rhinoceroses resembled the lacked horns and small horses. The largest land mammal ever to have lived was not an elephant but Indricotherium, which is a perissodactyl that was 6 metres (20 ft) long and could browse the treetops like a giraffe.

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Evolution

Rhinocerotoids diverged from the other perissodactyls by the early Eocene. Fossils of Hyrachyus Eximius found in North America date to this period. This small hornless ancestor resembled either a tapir or small horse more than a rhino. Three families, at times grouped together as the superfamily Rhinocerotoidea, evolved in the late Eocene, namely the Amynodontidae, Hyracodontidae, and Rhinocerotidae.

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Hyracodontidae

Hyracodontidae is also called "running rhinos," which have shown adaptations for speed and would have looked more like horses than modern rhinos. The smallest hyracodontidae were dog-sized, whereas the largest was Paraceratherium, which is one of the largest known land mammals that ever existed. The hornless Paraceratherium was almost ten metres long and five metres high and weighed as much as 15 tons. Similar to giraffes, they ate leaves from trees. Hyracodontids spread around Eurasia from the mid-Eocene to the early Miocene.

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Rhinocerotidae

Rhinocerotidae, the family that includes all modern rhinoceros, originally emerged in Eurasia around the Late Eocene. The earliest members of the Rhinocerotidae were numerous and small; at least 26 genera lived in North America and Eurasia until a wave of extinctions in the middle Oligocene wiped out most of the smaller species.

However, many independent lineages survived. Monoceros, which are pig-sized rhinoceros, had two horns on their side-by-side. The North American Teleoceras had short legs, a barrel chest and lived until up to 5 million years ago. The last rhinos that lived in the Americas became extinct during the Pliocene.

During the Miocene, the modern rhinos are thought to have begun dispersal from Asia. Alongside the extant species, 4 additional species of rhinoceros survived into the Last Glacial Period: Elasmotherium sibiricum, the woolly rhinoceros, and two species of Stephanorhinus, the Narrow-nosed and Merck's rhinoceros. The woolly rhinoceros appeared in the China region up to 1 million years ago and first arrived in Europe nearly 600,000 years ago.

It reappeared 200,000 years ago, alongside the woolly mammoth, and has become numerous. Elasmotherium was five meters long, two meters tall, and weighed around five tons, with a single enormous horn, long legs for running and hypsodont teeth. The latest well-known dated bones of Elasmotheriumin are found in the south of Western Siberia date as recently as 39,000 years ago.

Predators, Poaching and Hunting

Adult rhino rhinoceros contain zero real predators in the wild, other than humans. However, the young rhinos can fall prey to crocodiles, big cats, hyenas, and African wild dogs.

Although rhino rhinoceros are defined as large and aggressive and have a reputation for being resilient, they are very easily poached; they visit water holes every day and may be easily killed while they drink. As of 2009 - December, poaching increased globally while the efforts to protect rhinos are considered increasingly ineffective.

The most serious estimate that only 3% of the poachers are successfully countered is reported in Zimbabwe, while Nepal largely avoided the crisis. Poachers have become sophisticated. South African officials have called for urgent action against poaching after the poachers killed the last female rhino in the Krugersdorp Game Reserve near Johannesburg.

Statistics from South African National Parks exhibit that 333 rhinoceros were killed in South Africa in 2010, increasing to 668 by 2012, over 1,004 in 2013, and around 1,338 killed in 2015. In a few cases, rhinos are drugged and their horns removed, while in the other instances, more than the horn is taken.