Penguin

Aptenodytes

Anatomy

Penguins are superbly adapted to an aquatic life. Their wings have become flippers, useless for flight in the air. In the water, however, penguins are astonishingly agile. Within the smooth plumage a layer of air is preserved, ensuring buoyancy. The air layer also helps insulate the bird in the icy waters of the Antarctic. The plumage of penguins in tropical and temperate zones is much thinner.

Related Topics:
Wing - Plumage

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On land, penguins use their tails and wings to maintain balance for their upright stance.

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All penguins have a white underside and a dark (mostly black) upperside. This is for camouflage. A predator looking up from below (such as an orca or a leopard seal) has difficulty distinguishing between a white penguin belly and the reflective water surface.

Related Topics:
Camouflage - Orca - Leopard seal

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Diving penguins reach 6 to 12 km/h, though there are reports of velocities of 27 km/h (which are probably realistic in the case of startled flight). The small penguins do not usually dive deep; they catch their prey near the surface in dives that normally last only one or two minutes. Larger penguins can dive deep in case of need. The Emperor Penguin has been recorded reaching a depth of 875 feet (270 metres) and staying submerged for 18 minutes.

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On land, penguins are clumsy. They either waddle on their feet or slide on their bellies across the snow, a movement called "tobogganing", which allows them to conserve energy and move relatively fast at the same time.

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Penguins have an excellent sense of hearing. Their eyes are adapted for underwater vision, and are their primary means of locating prey and avoiding predators; in air, conversely, they are nearsighted. Their sense of smell has not been researched so far.

Related Topics:
Hearing - Eye

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They are able to drink salt water safely, because a gland near their eyes filters excess salt from the bloodstream. The salt is excreted in a concentrated fluid from the nasal passages.

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Penguins have no external genitalia.http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2002/02/21/wpeng21.xml Consequently, chromosome testing must be done in order to determine a penguin's sex.

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