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Research paper topic: Penguins - 1512 words
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Penguins The signature Species of the Southern Hemisphere (Antarctica) - the mascot if you will - is the penguin. There are not one and no fewer than seventeen species of penguins. Penguins are flightless birds in which several factors are contributing to the reduction of the penguin population. These contributing factors are both man-made and naturally occurring. The origin of the word penguin has been the subject of debate for a long period of time.
Researchers and historians theories range from reference to the amount of fat (penguigo in Spanish and pinguis in Latin) penguins possess to the claim that the word was derived from two Welsh words meaning white head. (Sparks and Soper, 1987) Penguins are comical and funny birds. Blue/black on the upper half of their body and white on the lower half, they look as though they are all dressed up for a formal dinner or show but have no place to go! Penguins are flightless birds, which have adapted to living in the cooler waters of the Southern Hemisphere. They generally live on islands and remote continental regions that are free of land predators. Their inability to fly has been detrimental to their survival on land.
Some species of penguins spend as much as 75% of their lives in the ocean, yet they all breed on land or sea ice attached to land. The seventeen species found today are thought to have evolved from flying birds more than forty million years ago. To date, the discovery of all penguin fossil fragments has been limited to the Southern Hemisphere. Records show that prehistoric penguins were found within the range of present-day penguins. (Sparks and Soper, 1987) All penguins have a very similar torpedo-shaped body form, which is conducive for swimming.
They have a large head and a short neck with an elongated body. Penguin species vary greatly in size. For example, the Emperor penguin is the largest of the penguin species, standing 3.7 feet and weighing between sixty and ninety pounds. The smallest penguin in the species is the Fairy penguin, standing only sixteen inches and weighs less than 3 pounds. Penguins wings are highly modified to form a stiff paddle-like flipper used for swimming. Each flipper is covered with short, scale like feathers. The long wing feathers typical of most birds would be too flexible for swimming through water.
(Sparks and Soper, 1987) A penguins tail is short and wedged shaped with fourteen to eighteen stiff tail feathers. The legs and webbed feet with visible claws on a penguin are set back on the body so that when on land, the penguin is able to stand. Penguins walk with short steps or hops, sometimes using their bills or tails to assist themselves on steep climbs. (del Hoyo, et al., 1992) When in the ocean swimming, penguins use their feet and short stubby tail as a rudder to guide them through the water. Penguins bones are solid and heavy which help them to remain submerged to reduce the energy that they need for diving.
Penguins are able to withstand the extreme cold because of the insulation provided by their feathers. Feathers are highly specialized, broad and closely spaced helping to keep water away from the penguins body. Penguins have more feathers than most birds, having about seventy feathers per square inch on their body. Most penguin species goes through one complete molting cycle per year, which usually happens after breeding season. The exception to this is the Galapagos penguin which annually go through 2 molts.
(del Hoyo, et al., 1992) For penguins, molting is a very important process because feathers wear out when penguins come in contact with each other, as well as with the ground and water. The molting period varies between one species to another. Usually the time period is anywhere from thirteen to thirty-four days. Regular preening of the feathers is essential as penguins obtain oil from their tails to coat their feathers for waterproofing. Penguins in warmer temperate zones have a thinner plumage of feathers and fat layer than their counterparts of the polar species.
To keep warm in near freezing waters, penguins have a highly developed heat exchanged system of blood vessels in the flippers and legs which helps the heat loss at the core of the body. To avoid heat loss in a penguins body, the penguin has 2 internal temperatures. A penguin has a normal body temperature and a temperature of the environment close to the limbs of the body. Tropical penguins can overheat very easily; so in order for them to lose the body heat, they usually use their flippers to get rid of excess heat. They also have bigger flippers than their polar penguin ancestors.
Penguins communicate with each other by different ritual behaviors such as head and flipper waving, calling, bowing, gesturing and preening. Penguins communicate by displays or vocalization and performing physical behavior. They use many vocal and visual displays to communicate nesting and territories along with mating information. They also use displays in partner and chick recognition, and defense of intruders. (Sparks and Soper, 1987) Territorial disputes can lead to aggressive postures such as stares, pointing and even charging each other.
Also during courtship and mating, other rituals are included which are called ecstatic displays. In these particular displays, an unattached male penguin will pump his chest several times, stretch his head upwards and move his flippers about away from his body. During this display, the male penguin also emits a loud harsh sound. In doing this, other male penguins in the colony begin to exhibit the same behavior which in turn begins the breeding cycle within the colony. When breeding occurs, one is unable to distinguish male and female penguins because they are not sexually dimorphic.
There is one particular penguin that one can be told apart called the Crested penguin. Other ways of telling which penguin is male or female is that males are usually more robust and have larger bills. Also during mating season, female penguins are identifiable by muddy footprints left behind by males during mating activity. Males and female penguins may take from 3 to 8 years before they reach sexual maturity. With some smaller species of penguins, breeding can occur between 3 and 4 years; but with larger penguins, breeding does not occur until much later in life, and then some do not breed until the eighth year.
The King penguin has the longest breeding cycle of all of the penguin species, lasting fourteen to sixteen months. A female King penguin may produce a chick twice in every 3 breeding seasons. (Sparks and Soper, 1987) The Fairy penguin has the shortest breeding cycle in the species, about fifty days. When penguins begin to mate, the courtship varies from species to species. Courtships begin with both visual and auditory displays as mentioned above. In many of the species, the male displays first to establish a nesting site and then attracts a suitable mate.
However during this display, the female makes the mate selection. Most penguin species are monogamous meaning one female breeds with one male during a breeding season. However, if a male penguin arrives late to his destination for breeding, this could be grounds for divorce. Most female Emperors and King penguins mate within twenty-four hours after arriving at the rookery. If the male is late or does not show up during this time period, the female will move on and find another mate. When penguins return to the rookery each breeding season, most tend to be faithful and return to the same place.
The males tend to arrive first to set up the nesting site prior to the females arrival. Most species of penguins nest on the surface, in open habitats, and many have only a rudimentary nest consisting of a hollow amongst boulders, tussocks, or other vegetation lined with a few stones or pieces of grass. (Williams, 1995) The Emperor and King penguins do not build a nest for their young. The reason for this is that when one of these species lays an egg, they stand upright while incubating a single egg. The eggs rest on the top their feet under a loose fold of skin. This loose fold of skin, which is used for incubating the egg, is called a broodpatch. The broodpatch contains numerous blood vessels that when blood is transferred to this area, heat is transferred to incubate the egg.
After a female penguin lays her egg, she returns to the ocean to feed and the male incubates the egg on his feet for as long as sixty days or until the egg hatches and a baby chick emerges. Usually in most cases, the female Emperor penguin returns from feeding in the ocean just about the same time the egg is ready to hatch. If she does not return in time and the egg hatches, the male penguin feeds the baby chick with a milky fluid from his throat. The baby chick is covered with a downy coat and is kept under the broodpatch until it is 6 to 10 days old. After this period of time, the baby chick begins to regulate i ...
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