Whales
Whales are
sea-living
mammals. Therefore,
they breathe air, but cannot survive on land. Some species are very large
indeed and the blue whale, which can exceed 30 m in length, is the largest
animal to have lived on earth.
Superficially,
the whale looks like a fish, but there are important differences in its
external structure: its tail consists of a pair of broad, flat, horizontal
paddles (the tail of a fish is vertical) and it has a single nostril on top of
its large, broad head. The skin is smooth and shinny, and beneath it lies a
layer of fat (blubber). This is up to 30 cm in thickness and serves to converse
heat and body fluids.
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