We’ve all heard of mermaids. They are the beautiful half-human， half-fish creatures(生物). They have the head and body of a human and the tail of a fish. We also know that mermaids only exist in fairy tales. But where did all the stories about these creatures come from? If you have ever seen a manatee， then you might have an idea.
Manatees， which are also called sea cows， are mammals(哺乳动物) that live in the sea. Since they are mammals， they have to swim up to the surface to breathe air. Many people believe that the story of the mermaid began with the ancient sailors who saw the manatees putting their heads out of the water to breathe. Because manatees are upright when they do this， it looks like they are standing. If a sailor saw a manatee doing this from far away across the sea， it is possible that the sailor would mistake the manatee for a creature that is half-human， half-fish.
Mermaids are described as having very long hair. This is probably because manatees like to swim up to the surface of the water in areas where there is sea grass. Manatees eat all kinds of plants in the sea， including sea grass. The sea grass around the manatee’s head when they eat could create a picture of long hair.
Manatees also have powerful tails that are very similar to the fish-like tail of a mermaid. The sailors probably watched manatees come up for air and then swim back below the surface， using their paddle-shaped tails. This would explain why the sailors thought mermaids had fish-like tails.

What are mermaids?
Where do manatees live?
Do manatees need to breathe air out of water?
What do manatees eat?
Why did the ancient sailors mistake manatees for mermaids?