Penguins: The Flightless seabirds

Join me for dinner at Antarctica?

Penguins are comical looking birds. Blue-black above and white below, they look as though they are dressed in a tuxedo for a formal dinner!

Class: Aves (birds)
Order: Sphenisciformes (Penguin-like birds)
Family: Spheniscidae (Penguins)

Emperor penguin (Aptenodytes forsteri) adults & chick, Dawson-Lambton Glacier, Antarctica.
© WWF-Canon / Fritz PÖLKING

Penguins are a group of flightless seabirds found between 45 and 60 degrees south in the Southern Hemisphere. The greatest number is found on the coasts of Antarctica and on the subantarctic islands. Some penguin species live as far north as the Galapagos Islands on the Equator and the subtropical coasts of South America, South Africa and Australia.

But even in warm areas, they live only where cold water currents exist, such as the Humboldt Current along the western coast of South America and Benguela and Agulhas Currents around South Africa. Of the 17 species of penguins, the largest, such as the Emperor and Adelie penguins, are found in the Antarctic.

Species vary in size
Penguins vary widely in size and weight but are remarkably similar in structure and plumage. Size and weight can range from the 40cm, 1kg Little Blue Penguin to the 1m, 35kg Emperor Penguin. Some kinds of penguins have distinguishing marks like crests, crown and stripes which make them easier to identify.

Penguins have a dense mass of overlapping, oil-tipped feathers and a thick layer of fat under the skin which combine to provide good insulation and waterproofing.

Penguins' bills are generally short and stout with a strong grip. Larger penguins like the Emperor and King have down curved bills, possibly to help them catch fast swimming fish and squid in deep cold waters.

Jackass Penguin (Spheniscus demersus) swimming in the sea. Endangered Boulders Beach, Cape Peninsula.
© WWF-Canon / Martin HARVEY

Swimming champs
Penguins have highly streamlined bodies with wings reduced to strong, narrow, stiff flippers. They can move very fast (up to 36kmph) under water, and are able to stay in the icy sea for long periods.

A penguin's legs and webbed feet are short. The legs are set well back on the body and are used, along with the strong tail, as rudders to steer them through the water. Their bones are comparatively solid and weigh a little less than water, thus reducing the energy required to dive.

On land, penguins are less agile. They almost always stand upright, using the stout tail feathers as a prop. They waddle rather than walk because of their short legs, but on ice they can move fast, even tobogganing on their bellies.

Keeping warm, keeping cool
To keep warm in near-freezing waters, penguins have a highly developed 'heat exchange' system of blood vessels in the flippers and legs that helps heat loss at the core of the body. Penguins avoid losing body heat by having 2 internal temperatures - normal in the most of the body and close to the environment temperature in the limbs.

In harsh conditions, emperor penguins and chicks huddle together for warmth. The centre of a huddle can be about 10°C warmer than the edges. Birds take turns to occupy the outer positions in the huddle.

Tropical penguins overheat easily, so they have larger flippers and areas of bare skin on the face that help to lose heat. Penguins are so well insulated that they must sometimes cool themselves by fluffing out their feathers and flooding blood through the blubber. They also live in burrows to avoid too much hot sun.

Food fads
Penguins feed on small fish, floating crabs and squids. Most species of penguins eat snow, and all of them drink salt water and fresh water. They can endure long periods without food on land.

Emperor penguin (Aptenodytes forsteri) chick, Dawson-Lambton Glacier, Antarctica.
© WWF-Canon / Fritz PÖLKING

Rearing the young
Penguins are very social animals, breeding in groups or in large noisy colonies called rookeries. They mate on shore in spring - almost always with the same partner. Penguins lay 1 or 2 eggs, though usually only 1 chick is reared.

Nests in polar regions range from a simple hollow in the ground to an elaborate structure of pebbles, bones and sticks. Chinstrap penguins sometimes nests in snow which melts, leaving the bird in a water-filled hole. The King Penguin does not build a nest at all. In temperate zones, penguins nest in scattered grasses, bushland or holes in sandunes.

After laying her egg, a mother Emperor Penguin returns to the sea to feed and the father incubates the egg on his feet for as long as 60 days till the egg hatches! Usually, the mother returns to care for the chick about the time it hatches, but if she is still away at sea, the father penguin feeds the baby chick with a milky fluid from his throat.

The baby is covered with a sparse downy coat and is carefully brooded till it is 6 to 10 days old. After this, they begin to regulate their own temperature, but often chicks are herded together in tight groups to keep warm.

Penguins moult (shed their old feathers) soon after the young have become independent. Polar penguins change the entire plumage at once in a so-called 'catastrophic moult' with new feathers pushing the old ones out of the skin. Later, the old layer falls out in whole patches

Penguin facts

• Early Antarctic explorers actually thought penguins were fish and classified them accordingly. In fact, as birds, they are superbly designed for their job, flying underwater with great skill.
• Penguins have more feathers than most other birds, with about 70 feathers per square inch.
• The blackish upperparts and whitish underparts of penguins are an effective camoflage. Penguins are harder to see against the lighter sky when viewed from below, and the darker waters when viewed from above. This makes them harder to spot by both predators and prey.