Penguins are stout-bodied, short-legged, flightless birds superbly adapted for swimming underwater. Their wings resemble flippers and their bodies are covered with short, scaly feathers with downy bases. All 6 genera and 18 species, in the family Spheniscidae, are blackish above and white below, but some are banded across the breast (Spheniscus) and others have ornamental yellow crests (Eudyptes). Penguins are found in the colder waters of oceans of the Southern Hemisphere, breeding near the equator on the Galapagos Archipelago, in southern South America and Africa, in Australia and New Zealand, and on many islands. Only two species, the adelie and the emperor, breed in Antarctica.
Penguins swim underwater with powerful strokes of their wings and use their webbed feet
and stiff tail as rudders. Sometimes they make a series of porpoiselike leaps from the
surface at speeds approaching 40 km/h (25 mph). Although penguins feed mainly on small
crustaceans (krill), fish, and squid near the surface, the emperor penguin may descend up
to 260 m (850 ft) in search of food. Penguins come ashore by walking onto protected
beaches or by vaulting out of the surf to land upright on the ice or rocks. They then
waddle erect, climb steep slopes, or toboggan on their bellies over the snow.
Penguins gather into large colonies to breed, returning year after year to the same
rookery. The colonies are noisy with harsh calls and alive with the antics of courtship or
mutual displays in which the wings are typically held extended and the bill pointed
skyward.
The female emperor penguin lays her egg in May and then goes to sea to feed while the male
incubates continuously for two months without eating. He stands on the Antarctic ice in
the perpetual darkness of winter, holding the egg on his feet under a fold of abdominal
skin. When the female returns to care for the newly hatched chick, the male goes to sea to
regain his lost weight. The downy chicks herd together into creches for warmth and
protection as they get older. Chicks feed by reaching into their parents' throats for food
that is brought from the sea. Mortality of the chicks is often high (40 to 80 percent)
because of severe storms and predation by skuas and sheathbills. Although their eggs were
once harvested and adults slaughtered for their oil and skin, penguins are now widely
protected.