penguin

Penguin's Classification

What exactly are penguin?

Penguin are a group of aquatic flightless birds. Although almost all penguin species are native to the Southern Hemisphere, they are not found only in cold climates, such as Antarctica. In fact, only a few species of penguin live so far south.


General Features

The stocky, short-legged appearance of penguins has endeared them to people worldwide. They range from about 35 cm in height and approximately 1 kg in weight in the blue, or fairy penguin to 115 cm and 25 to 40 kg in the emperor penguin(Aptenodytes forsteri). Most are black on the back and white below, often with lines of black across the upper breast or spots of white on the head. Colour is rare, being limited to red or yellow irises of the eye in some species; red beaks or feet in a few; yellow brow tufts in the three species of Eudyptes; and orange and yellow on the head, neck, and breast in the emperor and king(A. patagonica) penguins.

The total populations of some species, such as the emperor, are estimated in the hundreds of thousands, but most species of smaller penguins certainly run into the millions.

Reproduction

The majority of species breed only once each year. Certain species, such as the African Penguin, probably other members of this genus, and the blue penguin, breed twice a year. The king penguin breeds twice in three years. One egg is laid by the emperor and king penguins; all others lay two or occasionally three. Most penguins begin breeding in the austral (southern) spring or summer. King penguins are on a 14- to 18-month cycle, and the timing of an individual pair depends on the success or failure of the previous breeding attempt. Some populations of the gentoo penguin also breed in winter. The breeding of the emperor penguin begins in autumn, apparently timed so that the long developmental period will produce the young in midsummer, when their chances of survival are greatest.

The gentoo, which has a circumpolar distribution, is notable for its lack of synchrony among populations, but otherwise its breeding schedule is essentially comparable to that of most other species. In the Crozet Island off southern Africa, for example, egg laying takes place in July. The two eggs are incubated for 35 or 36 days, and the rearing of the chick takes two months. The last immature birds go to sea in January. 

The lifespan of a penguin is usually around 20 years for emeperor penguin and 6 years for little penguin.

Locomotion & Orientation

Penguins are adapted for rapid locomotion in water, in which the wings, or flipper, are used for propulsion; the birds “fly” underwater. When moving at high speed, they frequently leave the water in leaps that may carry them a metre or more through the air; it is during this time that they breathe.

On land, penguins are much more awkward, even amusing, as they rock from side to side as they walk. Despite their short legs, however, penguins can run with surprising speed.

On snow or ice, many penguins “toboggan,” sliding on the belly as they propel themselves with the feet and flippers. The flippers, along with the beak, are the prime weapons in defense and attack.

Studies of penguins transported to the interior of Antartica have found that they are able to find their way back to the ocean by using the sun as a directional aid. It is probable that the same means of orientation is used at sea. Upon approaching the coast they are able to recognize features of the shoreline and ocean bottom.

Classification

ORDER SPHENISCIFORMES (PENGUINS)

1.Genus Eudyptes : crested penguin

2.Genus Spheniscus : blackfooted, jackass penguin

3.Genus Pygoscelis

4.Genus Aptenodyte : emperor & king penguin

5.Genus Eudyptula : blue penguin

Form

The feet are located much farther back than those of other birds, with the result that the bird carries itself mostly upright; its walk can thus be described as plantigrade. The sole comprises the whole foot instead of just the toes, as in other birds. The most notable characteristic of the group is the transformation of the forelimb into a paddle. This is accompanied by a body morphology particularly adapted to movement in a liquid medium. The thoracic (rib) cage is well developed, and the sternum bears a pronounced keel for the attachment of the pectoral muscles, which move the flippers. The flipper has the same skeletal base as the wing of flying birds but with its elements shortened and flattened, producing a relatively rigid limb covered with very short feathers an ideal organ for rapid propulsion. The body plumage likewise consists of very short feathers, which minimize friction and turbulance. The density of the plumage and the layer of air that it retains provide almost complete insulation of the body.