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 birds in cold waters. On land, penguins use their
tails and wings to maintain balance for their upright stance.
All penguins are countershaded
- 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 distinguishing between a white penguin belly and the
reflective water surface. The dark plumage on their backs camouflages them from
above.
Diving penguins reach 6 to
12 km/h (3.7 to 7.5 mph), though there are reports of velocities of 27 km/h (17
mph) (which are more 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. Dives of the large Emperor Penguin have been recorded which
reach a depth of 565 m (1870 ft) and last up to 22 minutes.
Penguins 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.
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.
They are able to drink salt
water safely because their supraorbital gland filters excess salt from the
bloodstream. [1][2][3] The salt is excreted in a
concentrated fluid from the nasal passages.
Some penguins mate for
life, others for just one season. They generally raise a small brood, and the
parents cooperate in caring for the clutch and for the young. During the cold
season on the other hand the mates separate for several months to protect the
egg. The male stays with the egg and keeps it warm, and the female goes out to
sea and finds food so that when it comes home, the baby will have food to eat. Once
the female comes back, they switch. When mothers lose a chick, they sometimes
attempt to "steal" another mother's chick, usually unsuccessfully as
other females in the vicinity assist the defending mother in keeping her chick.
As the young grow, they assemble in large groups called crèches in some
species, such as Emperor Penguins.
Homosexual Behaviour
In early February 2004 the New
York Times reported a male pair of Chinstrap penguins in the Central Park
Zoo in New York City were partnered, and when given an egg which needed
incubation, successfully hatched it. Other penguins in New York have also been
reported to be forming same-sex pairs.[4]
This was the basis for the
children's picture book And Tango Makes Three. The couple about whom the
book was based, Roy and Silo, would see further interesting developments in
their relationship when in September 2005, Silo left Roy for a female penguin.
Zoos in Japan and Germany
have also documented male penguin couples.[5] The
couples have been shown to build nests together and use a stone to replace an
egg in the nest. Researchers at Rikkyo University in Tokyo found twenty such
pairs at sixteen major aquariums and zoos in Japan. Bremerhaven Zoo in Germany
attempted to break up the male couples by importing female penguins from Sweden
and separating the male couples; they were unsuccessful. The zoo director
stated the relationships were too strong between the older couples.
Wikipedia
http://en.wikipedia.org/w/index.php?title=Penguin&action=history