Penguin

Penguins (order Sphenisciformes, family Spheniscidae) are an order of flightless birds living in the southern hemisphere. more...

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Species and habitats

There are 17 or 18 known species worldwide, depending on whether the two Eudyptula species are counted as distinct. more...

Although all penguin species are native to the southern hemisphere, they are not, contrary to popular belief, found only in cold climates, such as Antarctica. In fact, only a few species of penguin actually live so far south. Three species live in the tropics; one lives as far north as the Galápagos Islands and will occasionally cross the equator while feeding.

The largest species is the Emperor Penguin (Aptenodytes forsteri): adults average about 1.1 meters (3 ft 7 in) tall and weigh 35 kilograms (75 lb) or more. The smallest penguin species is the Little Blue Penguin (also known as the Fairy Penguin), which stands around 40 cm tall (16 in) and weighs 1 kilogram (2.2 lb). Generally larger penguins retain heat better, and thus inhabit colder regions, while smaller penguins are found in temperate or even tropical climates.

Penguins are gregarious. Most feed on krill, fish, squid, and other forms of sealife caught while swimming underwater. They spend half of their life on land and half in the oceans.

When it comes to the gender ratio between male and female penguins in the wild, there are usually far more female penguins than males. Scientists speculate that this is because the male must endure the harshest role in the caretaking of a couple's egg. While the female takes a dangerous journey to eat, as well as store food in her body for the baby, the male must keep the egg warm and endure the extremely harsh climate, unable to eat for up to four months. When the female eventually returns,the male will have lost half his body weight. After the female returns and takes care of the egg, the male must now go off to find food, as he will be on the brink of starvation. Being weakened by the lack of food, many of the males will not return to see their families again.

Due to the gender ratio, penguins are one of the few species on the planet whose females fight over single males during mating season, due to the comparatively low number of male penguins.

One of the most baffling forms of behaviorof the penguin comes when a mother loses her chick, either due to its being unable to endure its first storm, or due to other reasons such as predators. When a mother loses its chick, they have been known to actually attempt to steal another mother's living chick- presumably in order to deal with the grief of the loss. This behavior has amazed scientists, as it is an emotional outburst opposed to an instinctual behavior; something many animals do not exhibit when losing their young. Many have used this as prime evidence for decades that many animals have near human-like emotions and feelings, often for the sake of animal rights.

Evolution

Penguins are actually very old birds. The oldest fossils of penguins emerged in the Eocene era more than 40 million years ago. However these fossils proved that prehistoric penguins were already flightless and seagoing, so their origins may go as far back as 65 million years ago

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.

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

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.

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.

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.

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 a gland near their eyes filters excess salt from the bloodstream. The salt is excreted in a concentrated fluid from the nasal passages.

Penguins have no external genitalia. Consequently, chromosome testing must be done in order to determine a penguin's sex.

Mating Habits

Most penguins mate for life. They generally raise a small brood, and the parents cooperate in caring for the clutch and for the young.

Gallery

Read more at Wikipedia.org