Do you know the whales in the sea? There are many relatives(亲属) in the whale family and they always live together with whales.

Few people know dolphins(海豚) are part of thewhale family. Dolphins are not fish. They are mammals (哺乳动物).They breathe air, and they have babies and feed them with milk.Dolphins are famous for their wonderful shows. They can jump high out of thewater and show turns in the air. These jumps give the dolphins time to breathe.

Porpoises(鼠海豚) are also in the whale familyand are quite like dolphins. But they are different in the size and shape ofthe mouth. The dolphin's mouth is long and thin, but the porpoise's is shortand thick. Dolphins are also more talkative than porpoises. Dolphins makesounds to talk with each other under water. But porpoises do not do this. Bothof them are smart and friendly to humans.

Not all the members of the whale family are friendly. Big whales aremuch easier to be angry than smaller dolphins or porpoises. An angry whale canbe dangerous. Perhaps this helped to create the story ofMoby Dickthatsank(使下沉) a ship and made all the people on it die inthe sea.