Read the text and answer the question! Whales are sea-diving mammals. They therefore breathe aim but cannot survived on land. Some species are very large indeed and the blue while, which can exceed 30 meters length, is the largest animal which lives on earth. Superficially, the while look rather like a fish, but there are important difference in its external structured; its tail consists of a paid of broad, flat horizontal paddle (the tail of a fish is vertical) and it has a single nostril on top of its breath, broad head. The skins is smooth and shiny and beneath it lies a later of flat (blubber). This is up to 30 meters in thickness and serves to conserved heat and body fluids. What is the text about?

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Read the text and answer the question!

Whales are sea-diving mammals. They therefore breathe aim but cannot survived on land. Some species are very large indeed and the blue while, which can exceed 30 meters length, is the largest animal which lives on earth. Superficially, the while look rather like a fish, but there are important difference in its external structured; its tail consists of a paid of broad, flat horizontal paddle (the tail of a fish is vertical) and it has a single nostril on top of its breath, broad head. The skins is smooth and shiny and beneath it lies a later of flat (blubber). This is up to 30 meters in thickness and serves to conserved heat and body fluids.

What is the text about?