Penguin

I

Introduction

Penguin, common name for 17 species of flightless seabirds widely distributed in cooler waters and along coastlines in the Southern Hemisphere. Skilled swimmers, penguins have streamlined, barrel-like bodies that reduce drag in the water. Their wings, modified to form thin, stiff flippers, provide propulsion while swimming. Unlike the bones of other birds, penguin bones are solid, not hollow, which helps them remain submerged underwater. On land penguins have a waddling gait due to their short, thick legs set far back on the body. Penguins come ashore to breed, but they are, in fact, true marine animals, spending as much as 80 percent of their lives at sea.

II

Range and Habitat

Although penguins are generally associated with extremely cold climates, only two species—the Adélie penguin (Pygoscelis adeliae) and the emperor penguin (Aptenodytes forsteri)—live on the frozen Antarctic continent. Most penguin species live in subantarctic regions (around and just north of the Antarctic Circle) or temperate regions farther north. The greatest variety of penguin species occurs in southern New Zealand, which is home to seven species, and the Falkland Islands, home to five species. Penguin populations are largest on the coast of the Antarctic Peninsula (the northernmost tip of Antarctica) and on subantarctic islands. One small species, the Galápagos penguin (Spheniscus mendiculus), lives on the Galápagos Islands just south of the equator, and several penguin species inhabit the hot, desert coastlines of South America and southern Africa. The birds living in these warmer regions rely on cold and nutrient-rich water currents to survive.

III

Physical Characteristics

Penguins vary in size from the little penguin (Eudyptula minor), which weighs 1.1 kg (2.4 lb) and is about 40 cm (16 in) tall, to the emperor penguin, which grows to 30 kg (66 lb) in weight and stands about 115 cm (45 in) tall. The emperor penguin is small compared to the fossil penguin Anthropornis, which lived 37 million to 45 million years ago on Seymour Island near Antarctica. Fossil records indicate that Anthropornis was around 170 cm (66 in) in height.

All penguins have a black back and head and a white breast, but individual species can be distinguished by certain physical characteristics. For instance, the birds in the genus Eudyptes are commonly known as crested penguins for the tuft of bright yellow plumage on their head. Adélie penguins have white, spectacle-like rings around their eyes. Other penguins can be distinguished by bare, pink skin on the head and neck, or varied black and white breast bands. Penguin bills can be black or red, ranging in shape from short and stout to long and curved. Penguin feet are webbed with three toes. Male and female penguins are similar in appearance, although males usually weigh more than females and there are small differences in bill size between the sexes.

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Penguins are well adapted to cold weather. Their short, stiff feathers form a dense waterproof coat that prevents excess heat loss. Some species have a thick layer of blubber under their skin, but this fat layer mainly acts as a food reserve and contributes little to insulation.

IV

Life of Penguins

Penguins spend most of their lives in water and they are excellent swimmers. They travel long distances underwater, propelling themselves with their flipper-like wings and using their webbed feet as rudders. They commonly leap out of the water—a movement known as porpoising—to breathe. On land penguins hop or waddle awkwardly, and in icy or snow areas they can toboggan on their stomachs, paddling themselves forward with their wings.

All penguins eat only when they are in the water, catching fish, squid, and crustaceans. Penguins search for food while swimming near the water’s surface and then swiftly dive to pursue their prey. Recently scientists have learned more about the diving behavior of penguins by attaching special miniaturized computers to the backs of the birds. These devices record various activities of penguins, providing data on the number and depth of dives made, swimming speeds, and even how often a bird catches and swallows prey. Early results from these studies indicate that penguins are champion divers. The large emperor penguin can reach depths of over 500 m (1,600 ft). A gentoo penguin (Pygoscelis papua) was recorded making over 450 successive dives in 15 hours, at times reaching depths of 160 m (525 ft).

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