Dolphins are not fish. They are mammals  .They live in groups and speak to each other in their own language. But they are quite different from almost all land animals. Their brain is as big as men's and they live a long life at least 20 or 30 years. Like some animals, dolphins use sounds to help them find their way around. They also use these sounds to talk to each other and to help them find food. They do not use their ears to receive sounds,but use the jaw--the lower part of the mouth. It is strange that dolphins are friendly to men, and for thousands of years, there are many stories about dolphins and men. In the 19th century, in a dangerous part of the sea near New Zealand,there was a dolphin. The seamen liked him very much and gave him a very good name, Jack. From 1871 to 1903 ,Jack met every boat in the area and showed it the way. In 1903 a passenger on a boat with the name of The Penguin shot and hurt Jack. Luckily the dolphin didn't die, and after a long time he was well again. He guided the ships through the area for nine more years, but he refused to help the boat of the Penguin. Today, some people still kill dolphins, but many countries in the world now protect them. In these places, people are not allowed to kill them. How do dolphins find their way?
They use their noses to smell the way. They use their ears to hear the sounds. They use their eyes to see the way. They use sounds to find the way.