Whales are a large animal that lives in the sea. They are not fish, as they need to come to the surface to breathe, the same as we do when we are swimming. There are many different varieties of whale. Some eat fish, penguins and seals, but the majority of whales have a large mouth full of tiny bristles that they use to filter tiny sea animals out from the water to eat. The whale is closely related to the dolphin.