A danc'n penguin with shades The signature species of Antarctica -- the mascot, if you will -- is the penguin. There are not one but no fewer than 17 species of penguins, of which only four breed on the Antarctic continent itself. These include the Adelie, the Emperor, the Chinstrap and the Gentoo penguins. Several other species are sometimes found within the Antarctic region, and penguins are found as far north as the Galapagos Islands, straddling the equator. But in general, the link in the public imagination between Antarctica and penguins is supported by the numbers -- there are millions of nesting pairs of Chinstrap penguins alone, and they are by far the most numerous creatures in the region. A front view of a penguin

Penguins are flightless birds which have adapted to living in the cooler waters of the Southern Hemisphere. The 17 species of penguins found today are thought to have evolved from petrel-like flying birds some 50 million years ago. Some species spend as much as 75% of their lives in the ocean, yet they all breed on land or sea-ice attached to the land.

A front view of a penguin All penguins have a very similar torpedo-shaped body form, though they vary greatly in size. Penguin wings are highly modified to form stiff paddle-like flippers used for swimming, and their feet and stubby tails combine to form a rudder. The penguin's bones are solid and heavy, which help them to remain submerged and reduce the energy needed for diving. Two running penguins

Penguins are able to withstand the extreme cold because insulation provided by their short, densely-packed feathers forms a waterproof coat. A thick layer of fat or blubber also serves as an energy store. These adaptations, among others, enable them to minimize heat loss in icy cold waters so they can cope with the harsh conditions of the Antarctic.