Emperor Penguins

Penquin group

Emperor penguins are twice the size of the next largest penguins, weighing an average of 66 pounds, though they can weight nearly 100 pounds and stand a little more than 3½ feet tall. They have a normal life span of 15 to 20 years, though some individuals may live substantially longer. The estimated population is 200,000 breeding pairs.

Penguin group

Unlike other birds, these birds do not build a nest. Once the female lays her egg, which is about one pound in size, the male immediately takes over the care, cradling the egg on top of his feet. Loose layers of skin around its stomach fold over the shell keeping the egg warm. During this incubation time, which lasts about 2 months and takes place during the most severe part of winter when there is 24-hour darkness, male birds will huddle together in large groups to protect each other from the wind, and to conserve body heat. They continue to rotate from the relatively warm interior of the group to the outer perimeter, allowing the birds on the outside to warm themselves nearer the center. The temperatures may reach -140° Fahrenheit and the winds can reach 125 miles per hour. These are the only Antarctic birds to breed during the winter, but by doing so, this allows the young birds to grow to independence during the summer when the food supply is most plentiful and predators are fewest.

As soon as the female has laid the egg, she will make her way to the water to feed, which may be 50 miles or more away. By the time the egg has hatched and the female returns, the male may have lost up to 50% of his body weight. He must now make his way over the miles of ice in order to find open water and begin feeding to replace his lost body weight. These remarkable creatures have been known to travel up to 600 miles on a fishing trip.

Hatching can take 2 or 3 days. By the time the chick hatches, the father will have fasted for 115 days. If the chick hatches before the mother’s return, the father will feed it with a curd-like substance that is produced in his esophagus.

Penguin chick and mother

The mother bird will return anytime from when the chick is hatched to 10 days following. At that point, the father will make his way to the sea and be gone for 3 to 4 weeks. Upon his return, the parents take turns fishing for food for the young. About 45–50 days after hatching, the chicks form a crèche huddling together for warmth and protection. During this time, both parents forage at sea and return periodically to feed their chicks.

Unlike most penguins which feed on krill, emperor penguins live on fish, squid, and crustaceans that are caught on long dives. Most dives last from 3 to 6 minutes and are 400 to 700 feet, however, they have been known remain submerged as long as 22 minutes and dive to a depth of 1800 feet where the pressure is 40 times greater than at the surface. Not only does the time far exceed that which a human being can hold their breath, but the pressure at that depth would give humans the bends. To prepare for these dives, the heart beat will increase from 60 to 70 beats per minute to 180 to 200. This allows for the storage of oxygen in the tissues. As soon as they hit the water, the heart beat slows and will drop as low as 20 beats per minute during most of the dive. Immediately upon resurfacing, the heart again returns to the rapid beat while the oxygen debt is paid back.

Penguins coming home from a fishing spree

These penguins have several physical adaptations that help to give it the ability to accomplish this, including an unusually structured hemoglobin to allow it to function at low oxygen levels that would otherwise cause loss of consciousness. In addition, they have solid bones to reduce barotraumas (physical damage to body tissues caused by a difference in pressure between an air space inside or beside the body and the surrounding gas or liquid), and the ability to reduce its metabolism and shut down non-essential organ functions. It is unknown how they avoid nitrogen induced decompression sickness.

Emperor penguins go through a molt every year between January and February. Their molt, however, is much shorter than for other birds, lasting only about 34 days. Their feathers emerge from the skin after they have grown a third of their total length, and before the old feathers are lost, thereby reducing heat loss. New feathers then push out the old ones before completing their growth.

Penguin feathers are densely packed; more so than any other bird with up to 100 feathers per square inch. Between these feathers and the skin, there is a layer of downy filament that acts as a layer of insulation. Muscles in the skin allow for the feathers to be held erect reducing heat loss by allowing for a layer of trapped air. In contrast, when they are in the water, the feathers are held tightly to the body forming a waterproof shield.

By the time the molt is completed the young are half the adult size and fledged. They all then make their trip to the open water, which by now is a lesser distance due to the summer melt. They will spend the next few months eating to gain the weight necessary to survive the coming winter.

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