People used to wonder how fish can hear sounds without ears. But the fact is that fish do have ears. We can't see the ears because they are inside fish's bodies, and they hear very well with them. Their listening is actually much better than man's.

    Many water animals make noises while they are doing something. Sounds are real words for them. By sounds, they know where they are and which way to go. When they face dangers or find food, they always make sounds to tell others the news.

    A new field in science is to learn the meanings of underwater sounds. People use the same method that they have used in learning the secrets of birds' calls. But this method is more difficult to use in the sea because many of the sea animals can't be easily followed and studied. But we have no any other better way to study the sounds in the sea. Perhaps the meanings of the calls of the sea animals will be known more clearly some day. It will be useful for us to learn the secrets of the sounds in the sea.