Wednesday, February 14, 2007


Penguins are excellently adapted to an aquatic life. Their wings have grow to be flippers, useless for flight in the air. In the water, however, penguins are astonishingly agile. Within the soft plumage a layer of air is preserved, ensuring buoyancy. The air layer also helps protect the birds in cold waters. On land, penguins use their tails and wings to maintain balance for their upright stance.
All penguins are counter shaded - that is, they 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 distinctive between a white penguin belly and the reflective water surface. The dark plumage on their backs camouflages them from over.
Diving penguins reach 6 to 12 km/h (3.7 to 7.5 mph), although there are information of velocities of 27 km/h (17 mph) (which are more practical in the case of startled flight). The small penguins do not generally 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. Dives of the large Emperor Penguin have been recorded which get to a depth of 565 m (1870 ft) and last up to 20 minutes.
Penguins either waddle on their feet or slide on their bellies across the snow, a movement called "tobogganing", which allows them to keep energy and move fairly fast at the same time.Penguins have an superb sense of hearing. Their eyes are personalized for underwater vision, and are their primary means of locating prey and avoiding predators; in air, equally, they are nearsighted. Their common sense of smell has not been researched so far.They are able to drink salt water securely because their supraorbital gland filters excess salt from the bloodstreamThe salt is excreted in a concentrated fluid from the nasal passages.

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