Black Rhinoceros

The **black rhinoceros** or **hook-lipped rhinoceros** (*Diceros bicornis*) is a species of rhinoceros, native to eastern and southern Africa including Botswana, Kenya, Malawi, Mozambique, Namibia, South Africa, Swaziland, Tanzania, Zambia, and Zimbabwe. Although the rhinoceros is referred to as *black*, its colors vary from brown to grey.

The other African rhinoceros is the white rhinoceros (*Ceratotherium simum*). The word "white" in the name "white rhinoceros" is often said to be a misinterpretation of the Afrikaans word *wyd* (Dutch *wijd*) meaning wide, referring to its square upper lip, as opposed to the pointed or hooked lip of the black rhinoceros. These species are now sometimes referred to as the square-lipped (for white) or hook-lipped (for black) rhinoceros.[5]

The species overall is classified as critically endangered (even though the South-western black rhinoceros is classified as vulnerable). Three subspecies have been declared extinct, including the western black rhinoceros, which was declared extinct by the International Union for Conservation of Nature (IUCN) in 2011.

## Description

An adult black rhinoceros stands 140–180 cm (55–71 in) high at the shoulder and is 3–3.75 m (9.8–12.3 ft) in length. An adult typically weighs from 800 to 1,400 kg (1,760 to 3,090 lb), however unusually large male specimens have been reported at up to 2,199–2,896 kg (4,848–6,385 lb). The females are smaller than the males. Two horns on the skull are made of keratin with the larger front horn typically 50 cm (20 in) long, exceptionally up to 140 cm (55 in).

The longest known black rhinoceros horn measured nearly 1.5 m (4.9 ft) in length. Sometimes, a third, smaller horn may develop. These horns are used for defense, intimidation, and digging up roots and breaking branches during feeding. The black rhino is smaller than the white rhino, and is close in size to the Javan Rhinoof Indonesia. It has a pointed and prehensile upper lip, which it uses to grasp leaves and twigs when feeding. The white rhinoceros has square lips used for eating grass. The black rhinoceros can also be distinguished from the white rhinoceros by its size, smaller skull, and ears; and by the position of the head, which is held higher than the white rhinoceros, since the black rhinoceros is a browser and not a grazer. This key differentiation is further illustrated by the shape of the two species mouths (lips): the "square" lip of the white rhinoceros is an adaptation for grazing, and the "hooked" lip of the black rhinoceros is an adaptation to help browsing.

Their thick-layered skin helps to protect the rhino from thorns and sharp grasses. Their skin harbors external parasites, such as mites and ticks, which may be eaten by oxpeckers and egrets. Such behaviour was originally thought to be an example of mutualism, but recent evidence suggests that oxpeckers may be parasites instead, feeding on rhino blood. It is commonly assumed that black rhinos have poor eyesight, relying more on hearing and smell. However, studies have shown that their eyesight is comparatively good, at about the level of a rabbit. Their ears have a relatively wide rotational range to detect sounds. An excellent sense of smell alerts rhinos to the presence of predators.

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