Penguin

Penguin, the most highly specialized of all aquatic birds, with 17 species in the order Sphenisciformes, restricted to the southern hemisphere. Completely flightless, the wings are reduced to flippers for “flying” through the water. Ungainly on land, penguins only leave the water to breed. The nest is usually a skimpy affair, emperor and king penguins brood their single eggs on their feet, covering them with only a flap of skin. Most species nest in colonies, some with as many as 500,000 members. Penguins are long-lived birds: the yellow-eyed penguin may live for 20 years or more.