THE EMPEROR PENGUIN

The Emperor Penguin is the tallest and heaviest of all living penguin species and only lives in the Antarctica. The male and female are similar in plumage and size, reaching 122cm in height and weighing anywhere from 22 to 45kg. The dorsal side and head are black and sharply delineated from the white belly, pale-yellow breast and bright-yellow ear patches. Like all penguins it is flightless, with a streamlined body, and wings stiffened and flattened into flippers for a marine habitat.

Its diet consists primarily of fish, but can also include crustaceans and cephalopods. In hunting, the species can remain submerged up to 18minutes, diving to a depth of 535m. It has several adaptations to facilitate this, including an unusually structured hemoglobin to allow it to function at low oxygen levels, solid bones to reduce barotrauma, and the ability to reduce its metabolism and shut down non-essential organ functions.

The Emperor Penguin is best known for the sequence of journeys adults make each year in order to mate and to feed their offspring. The only penguin species that breeds during the Antarctic winter, it treks 50–120km over the ice to breeding colonies which may include thousands of individuals. The female lays a single egg, which is incubated by the male while the female returns to the sea to feed; parents subsequently take turns foraging at sea and caring for their chick in the colony. The lifespan is typically 20 years in the wild, although observations suggest that some individuals may live to 50 years of age.

Adaptations to cold

A emperor penguin diving.

The Emperor Penguin breeds in the coldest environment of any bird species; air temperatures may reach 40C and wind speeds may reach 144km/h. Water temperature is a frigid −1.8C,which is much lower than the Emperor Penguin’s average body temperature of 39C. The species has adapted in several ways to counteract heat loss.] Feathers provide 80–90% of its insulation, and it has a layer of sub-dermal fat which may be up to 3cm thick before breeding. Its stiff feathers are short and densely packed over the entire skin surface. With around 15 feathers per cm2, it has the highest feather density of any bird species. An extra layer of insulation is formed by separate shafts of downy filaments between feathers and skin. Muscles allow the feathers to be held erect on land, reducing heat loss by trapping a layer of air next to the skin. Conversely, the plumage is flattened in water, thus waterproofing the skin and the downy underlayer.Preening is vital in facilitating insulation and in keeping the plumage oily and water-repellent.

The Emperor Penguin is able to thermoregulate (maintain its core body temperature) without altering its metabolism, over a wide range of temperatures. Known as the thermoneutral range, this extends from -10 to 20C .Below this temperature range, its metabolic rate increases significantly, although an individual can maintain its core temperature between 37.6 and 38.0C down to −47C. Movements by swimming, walking, and shivering are three mechanisms for increasing metabolism; a fourth process involves an increase in the breakdown of fats by enzymes, which is induced by the hormone glucagon.

Adaptations to pressure and low oxygen

In addition to the cold, the Emperor Penguin encounters another stressful condition on deep dives —markedly increased pressure of up to 40 times that of the surface, which in most other terrestrial organisms would cause barotrauma. The bones of the penguin are solid rather than air-filled, which eliminates the risk of mechanical barotrauma.Also this thik bones alow then to dive so deep with out floting. However, it is unknown how the species avoids the effects of nitrogen-induced decompression sickness.

While diving, the Emperor Penguin’s oxygen use is markedly reduced; as its heart rate is reduced to as low as five beats per minute and non-essential organs are shut down, thus facilitating longer dives. Its hemoglobin and myoglobin are able to bind and transport oxygen at low blood concentrations; this allows the bird to function with very low oxygen levels that would otherwise result in loss of consciousness.

Diet

The Emperor Penguin searches for prey in the open water of the Southern Ocean, in either ice-free areas of open water or tidal cracks in pack ice. One of its feeding strategies is to dive to around 50m, where it can easily spot sub-ice fish like the Bald notothen swimming against the bottom surface of the sea-ice; it swims up to the bottom of the ice and catches the fish. It then dives again and repeats the sequence about half a dozen times before surfacing to breathe.

I had foud the information in this wep pages:

http://www.emperor-penguin.com/emperor.html

http://www.siec.k12.in.us/west/proj/penguins/emperor.html

http://www.antarcticconnection.com/antarctic/wildlife/penguins/emperor.shtml

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