ABSTRACT
Most of the creatures in the sea are small, but some are huge. While some rays and sharks are the biggest fish, there are mammals, too, that have to come to the surface to breathe. Among these sea mammals are seals, walruses and whales. We tend to think of dolphins as being a separate group on their own, but they are, in fact, a group of small whales. Many kinds of seals live in cold seas and they have a thick layer of fat called blubber under their skin to keep them warm. The flippers that they have developed instead of legs mean that they make slow progress on land, but are very fine swimmers and can move very quickly once they get into the water. The sea is the seal's hunting ground where it searches for fish to feed on.
