Three living zebra species wear Africa's barcode coats
Zebras—subgenus Hippotigris—are African equines with black-and-white stripes. Living species are Grévy's, plains, and mountain zebras. Primary grazers on often poor forage, they flee lions yet can bite and kick. English zebra likely arrived via Romance languages, perhaps from Latin equiferus, "wild horse."
Alongside horses and donkeys, zebras belong to Equus, the last living genus of the horse family. Equus arose in North America; DNA from a 700,000-year-old Canadian horse bone dates the last common ancestor of living equines to about 4.07 million years ago. Zebras and asses parted close to 2 million years ago, the mountain zebra branched off around 1.6 million years ago, and plains and Grévy's zebras split about 1.4 million years ago. The quagga, hunted to extinction in the 19th century, is now considered a form of plains zebra.
The name probably traces through Portuguese ezebro or zebro to Latin equiferus, "wild horse," a term first used for a mysterious wild equine of medieval Iberia. In 1591 the Italian explorer Filippo Pigafetta noted Portuguese visitors applying "zebra" to the African animals, which Greeks and Romans had called hippotigris, "horse tiger."
Underneath, the skin is black; the coat is really white with black stripes, and foals start out brown and white. Each animal's pattern is unique and inherited, and species differences seem to stem from timing in the embryo, when stripes spaced 0.4 mm apart are laid down at three weeks in plains zebras, four in mountain zebras and five in Grévy's. Albino zebras with blonde stripes have been seen on Mount Kenya. Why stripes exist is still debated, but most evidence points to deterring biting flies; camouflage looks unlikely, since lions and hyenas probably cannot make out the stripes from a distance, and the case for dazzling predators is contested. Unusually among equines, zebras have longer front legs than hind legs.
Plains and mountain zebras live in stable harems of one stallion with several mares and their foals, whereas Grévy's males hold territories and mating is promiscuous. Lions are the chief predator. Zebras have never been fully domesticated, though captive crosses with horses and donkeys produce often-sterile zorses and zonkeys. The IUCN rates Grévy's zebra endangered, the mountain zebra vulnerable and the plains zebra near-threatened.
Source: Zebra
