In addition, many penguins have a thick insulating layer of fat under the skin. Some species are better equipped for cold weather than others. Penguins usually walk or hop and toboggan along on their breasts, pushing with wings and feet. They swim with great speed and agility. Some species progress by porpoising, which is swimming underwater some distance, emerging in a graceful arc to take a fresh breath, and submerging again.
Penguins feed on fish, cuttlefish, crustaceans, and other small sea animals.
In captivity the king and emperor penguins normally do not learn to pick up their own food, and after they have been taught to feed by strenuous forced feeding they must be fed by hand each day. Penguins are gregarious birds and are found in flocks even at sea. On land the colonies often number in the hundreds of thousands. Although the birds have suffered greatly at the hands of humans, who have slaughtered great numbers for their blubber and, more recently, for their skins, the inaccessibility of the Antarctic region has helped preserve the group. Natural enemies of the penguin include leopard seals, killer whales, and, in the case of young chicks and eggs, skuas.