At birth they are grey, black and brown, but as they get older their colouring changes. When they are mature, they are mainly white with black tails, fins and flippers. There is always a white patch under the chin and a black patch on the belly. It is possible to tell males from females by the shape of the black patch on the belly. It is shaped like a raindrop in males and like a horseshoe in females. The South American animals which are black, grey and white are smaller than those in the Indian ocean. They have small rounded flippers. The left one has serrations along the leading edge. Their dorsal fins are also rounded and always black. Their tail flukes have slightly rounded tips with a small notch in the middle.