A wide variety of fish live in the sea. Many types of fish live in fresh
water like rivers and lakes. Other types of fish live in the salt water
of the oceans and seas.
The water is not only the fishes' home, but it also provides them with
the food and oxygen they need to live.
Sea rays fly through the water like birds through air. The biggest rays are the manta rays. Some kinds of mantas can grow to over 20 feet from tip to tip, and can weigh more than 3000 pounds.
Although whales and dolphins live in water, they
are mammals. They cannot breathe under water. They must come to the surface
to breathe air. They breathe through a blowhole, or nostrils, on the top
of their head. Babies are born under water, but must be pushed to the surface
by the mother so the bady can take a breath.
The circulatory and respiratory systems have adapted to living in water.
Whales and dolphins can dive deep in the water on a single breath.
