Dolphins are marine mammals and cetaceans family. They live in the the ocean because they can swim. There are almost forty epecies of dolphin. It 's size vary between 120 cm and 950 cm.They can weight antill 10 tons. Dolphins are social animals and live in herds of up to a dozen individuals. Dolphins are carnivores, and it's main source of food fish ans squid, can live 25-40 years. There animals don't hibernate.