The crocodiles are the biggest existing reptiles in the nature nowadays. Its size is, in average, of eight meters, however at the time of the dinossauros, it has 140 million years, them had arrived to measure 30 meters of length. Today they live up to 80 years. They are found in rivers, lakes and quagmires in tropical and subtropical Africa and Madagascar. They inhabit, also, the coastal areas of the African west. The crocodiles swim with the aid of its powerful tail. In land, although to have short legs, if they put into motion fast. Property, seem floating trunks, what it deceives many of the victims of these reptiles. Córneas plates cover the head, the neck and the trunk of these reptiles. The tail is compressed laterally. The young crocodiles if feed of invertebrates, amphibians, reptiles, fish and other small vertebrates. The adults are fierce predators and if they feed of fish, turtles, aquatic birds, antelopes, zebras, great domestic animals and men. The teeth, implanted in alveoli, are used to destroy the canine tooth. The crocodiles act mainly to the night. During the day, they rest in the edges or sand banks, keeping the mouth opened in the hours of bigger heat. They make its nests with foliages. The position is of 20-50 eggs and the incubation period is of three months. One of the differences between them and alligators is in the dentition. The crocodiles when closing the mouth leave to appear its 4º tooth.