Zebra

About the zebra

Zebra is the common name for three living species of African equine known for black-and-white striped coats: the plains zebra (Equus quagga), Grévy's zebra (Equus grevyi), and the mountain zebra (Equus zebra). All three belong to the subgenus Hippotigris and share the genus Equus with horses and donkeys, the only living members of the family Equidae. A close relative, the quagga, was a distinctly striped subspecies of the plains zebra that was driven to extinction in the 19th century.

The English name traces through Italian, Spanish, or Portuguese, and possibly back to the Latin equiferus, meaning "wild horse." Ancient Greeks and Romans instead called the animal hippotigris, or "horse tiger." Beyond today's three living species, the fossil record includes extinct relatives such as E. oldowayensis, known from remains at Olduvai Gorge dating to about 1.8 million years ago, and the Cape zebra (E. capensis), which lived throughout southern and eastern Africa starting around 2 million years ago.

Like other wild equines, zebras have barrel-shaped bodies, tufted tails, long faces, and long necks topped with erect manes. Their thin legs each end in a single hoofed toe, and their front legs are longer than their back legs, a trait unique among living equines. Their eyes sit high and to the sides of the head, letting them watch for predators while grazing in tall grass, and their ears can swivel to track sound.

The stripes themselves are black on a base of black skin, not white skin with black markings — the coat only looks white because of the pattern of unstriped areas on the belly and legs. Each zebra's striping is unique and heritable, and the pattern is set early in embryonic development, with the timing differing slightly between the three species. Scientists have proposed several explanations for why zebras evolved stripes at all, including camouflage, confusing predators during a chase, warning coloration, aiding individual recognition among the herd, helping regulate body temperature, and deterring biting flies; of these, the fly-deterrent idea has the strongest research support, since zebra hair length roughly matches the reach of horsefly mouthparts and flies show a preference for landing on solid-colored surfaces over striped ones.

Their teeth are adapted for a grazing lifestyle, with large incisors for clipping grass and rough molars and premolars for grinding it down; males also have spade-shaped canines that can be used as weapons when fighting other males. Unlike horses, zebras and asses have chestnut-colored callosities only on their front legs. Genetically, zebras and horses split from a common ancestor around 4 to 4.5 million years ago, with zebras and asses diverging from each other close to 2 million years ago; the mountain zebra branched off first, around 1.6 million years ago, followed by the split between the plains zebra and Grévy's zebra around 1.4 million years ago. Fertile hybrids between plains and Grévy's zebra have been recorded in the wild, and captive zebras have also been crossed with horses and donkeys to produce zebroids — a zorse (zebra and horse), a zonkey (zebra and donkey), and a zoni (zebra and pony) — which are often born sterile and with dwarfism.

Behavior and diet

Zebras are primarily grazers, feeding on grasses and other vegetation of a quality too low for many other grazing animals to rely on. Their main predator is the lion, and a zebra's first response to a threat is to flee; when cornered, it will also bite and kick.

Social behavior differs between the three species. Plains zebras and mountain zebras live in stable harem groups made up of one adult stallion, several mares, and their foals, and within a harem, mares mate only with that harem's stallion. Grévy's zebra lives differently: individuals are solitary or move in loosely associated herds, and males instead hold territories that draw in females, making the species more promiscuous than its harem-forming relatives. Social grooming helps maintain bonds within plains and mountain zebra groups, and zebras more broadly communicate through vocalizations, body postures, and facial expressions.

Range and habitat

Zebras live across eastern and southern Africa, occupying a range of habitats that includes open savannahs, grasslands, woodlands, shrublands, and mountainous terrain. Despite historical pressure from the exotic animal trade — zebras have never been completely domesticated the way horses and donkeys have — they persist today across numerous protected areas within their African range.

Conservation status

Conservation status differs by species rather than applying to zebras as a single group. The IUCN Red List lists Grévy's zebra as endangered, the mountain zebra as vulnerable, and the plains zebra as near threatened. The quagga, a strikingly striped population of the plains zebra, was driven to extinction in the 19th century. Zebras today continue to be found across many protected areas in Africa, which supports their populations even where they face pressure outside those boundaries.