Penguins are flightless birds that are highly adapted for the marine environment. They are excellent swimmers and can dive to great depths. Emperor penguins can dive to over 500 m. Their shape makes them extremely agile underwater. They use their feet and tail as a rudder, and propel themselves with their flippers.
Penguins have a waterproof coat of short, overlapping feathers. They have a well-developed layer of fat for insulation.
Penguins feed on small fish and krill which they catch one at a time. Their main predators are other marine animals, such as leopard seals and killer whales. Skuas and sheathbills also eat penguin eggs and chicks.
Penguins are only found in the Southern Hemisphere. The greatest concentrations are on Antarctic coasts and sub-Antarctic islands.
There are 18 species of penguins, 5 of which live in Antarctica. Another 4 species live on sub-Antarctic islands.