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 the whale 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 the water and show turns in the air. These jumps give the dolphins time to breathe.

Porpoises（鼠海豚）are also in the whale family and are quite like dolphins. But they are different in the size and shape of the mouth. The dolphin’s mouth is long and thin, but the porpoise’s is short and thick. Dolphins are also more talkative than porpoises. Dolphins make sounds to talk with each other under water. But porpoises do not do this. Both of them are smart and friendly to humans.

Not all the members of the whale family are friendly. Big whales are much easier to be angry than smaller dolphins or porpoises. An angry whale can be dangerous. Perhaps this helped to create the story of Moby Dick that sank（使下沉）a ship and made all the people on it die in the sea.

Dogs like living with people. They are very friendly. They can do many things for people.

Some dogs help people to look after sheep, other dogs help them to find the lost children. And some of the dogs can help the blind.

There is a kind of dog whose name is Seeing Eye Dog. Now we can see this kind of dog all over the world. They are working for the blind. The Seeing Eye Dog is strong and easy to train. He helps the blind to walk from place to place. Before a dog becomes a Seeing Eye Dog, he must be in a training school for about three months. First the dog has to learn to sit or stay when he hears the trainer’s call. In his next lesson the dog learns to take his trainer across busy streets. The dog has many things to learn. At the end of the training, he must take tests. When he passes the tests, the Seeing Eye Dog will do things by himself.

Now he can help the blind people. The new master may be a man , a woman or even a child. It takes the dog and his blind master about a month to learn to work and live together.