Zebras are African equids best known for their distinctive white and black stripes. Their stripes come in different patterns unique to each individual. They are generally social animals and can be seen in small harems to large herds. Zebras are generally 2.3 m (8ft) long, stand 1.25-1.5 m (4-5ft) at the shoulder, and weigh around 300kg (660 lbs), although some can grow to more than 410 kg (900 lbs). In addition to their stripes, zebras have erect, mohawk-like manes. Unlike their closest relatives, horses and donkeys, zebras have not been truly domesticated. There are three species of zebra: the Plains Zebra, Grevy's Zebra and the Mountain Zebra. The Plains zebra and the Mountain Zebra belong to the subgenus Hippotigris, but the Grevy's zebra is the sole species of subgenus Dolichohippus. The latter resembles an ass while the former two are more horse-like. Nevertheless, DNA and molecular data show that zebras do indeed have monophyletic origins.