Both black and white rhinoceroses are actually gray. What distinguishes one from the other is not their color but their lip shape. The black rhino has a pointed upper lip, while its white relative has a squared lip. The difference in lip shape is related to their diets. Black rhinos get most of their sustenance from eating trees and bushes. They use their lips to pluck leaves and fruit from the branches. White rhinos graze on grasses, walking with their enormous heads and squared lips lowered to the ground. The white rhino is the larger of the two African species. It has a bigger head, due to the muscles that support its neck. Black and white rhinos have poor eyesight, but an excellent sense of smell and hearing. Both rhinos have a gestation period of approximately 16 months, and normally have one young.