ZEBRA

DO U KNOW IT?



Zebra - with black and white stripes is called a African donkey.

Zebras  are several species of African equids (horse family) united by their distinctive black and white stripes. Their stripes come in different patterns, unique to each individual. They are generally social animals that live in small harems to large herds. Unlike their closest relatives, horses and asses, zebras have never been truly domesticated.

There are three species of zebras: the plains zebra, the Grévy's zebra and the mountain zebra. The plains zebra and the mountain zebra belong to the subgenus Hippotigris, but Grévy's zebra is the sole species of subgenus Dolichohippus. The latter resembles an ass, to which it is closely related, while the former two are more horse-like. All three belong to the genus Equus, along with other living equids.

The unique stripes of zebras make them one of the animals most familiar to people. They occur in a variety of habitats, such as grasslands, savannas,woodlands, thorny scrublands, mountains, and coastal hills. However, various anthropogenic factors have had a severe impact on zebra populations, in particular hunting for skins and habitat destruction. Grévy's zebra and the mountain zebra are endangered. While plains zebras are much more plentiful, one subspecies, the quagga, became extinct in the late 19th century – though there is currently a plan, called the Quagga Project, that aims to breed zebras that are phenotypically similar to the quagga in a process called breeding back.

Etymology

Zebra in English dates back to c.1600, from Italian Zebra, perhaps from Portuguese, which in turn is said to be Congolese (as stated in the Oxford English Dictionary). The Encarta Dictionarysays its ultimate origin is uncertain, but perhaps it may come from Latin Equiferus meaning "Wild horse," from equus "horse" and ferus "wild, untamed".

Taxonomy and evolution

Horse evolution Zebras evolved among the Old World horses within the last 4 million years. Grévy's zebras (and perhaps also Mountain Zebras) are, together with asses and donkeys, in a separate lineage from other zebra lineages.This means either that striped equids evolved more than once, or that common ancestors of zebras and asses were striped and only zebras retained the stripes. Extensive stripes are posited to have been of little use to equids that live in low densities in deserts (like asses and some horses) or ones that live in colder climates with shaggy coats and annual shading (like some horses).

Fossils of an ancient equid were discovered in the Hagerman Fossil Beds National Monument in Hagerman, Idaho. It was named the Hagerman horsewith a scientific name of Equus simplicidens. It is believed to have been similar to the Grévy's zebra. The animals had stocky zebra-like bodies and short, narrow, donkey-like skulls. Grévy's zebra also has a donkeylike skull. The Hagerman horse is also called the American zebra or Hagerman zebra.

Size and weight

The common plains zebra is about 50–52 inches (12.2–13 hands, 1.3 m) at the shoulder with a body ranging from 6–8.5 feet (2–2.6 m) long with an 18-inch (0.5 m) tail. It can weigh up to 770 pounds (350 kg), males being slightly bigger than females. Grévy's Zebra is considerably larger, while the mountain zebra is somewhat smaller.

Gaits

Like horses, zebras walk, trot, canter and gallop. They are generally slower than horses, but their great stamina helps them outpace predators. When chased, a zebra will zig-zag from side to side, making it more difficult for the predator. When cornered, the zebra will rear up and kick or bite its attacker.