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Elephant seal, Antarctica
Gentoo penguin with two chicks
Adélie penguin rookery
The Antarctic Ecosystem
There are six different types of seals in Antarctica. Five species of seal, including the elephant seal and the crabeater seal, depend mainly on squid for their food. The most vicious. carnivorous seal is the leopard seal, which is a predator of penguins which feed in the Antarctic waters. Most species of whales, including the blue whale, are filter feeders. One exception is the killer whale, one type of which can be found in the Antarctic. Killer whales often hunt in packs and have even been known to attack other species of whales.
The small areas of Antarctica which are not covered with snow in the summer become covered by mosses and lichens. There are over 400 species of lichens found in Antarctica. These plants spend the winter under ice, sometimes as resistant spores, and grow rapidly in the summer months. There are only four species of flowering plants in Antarctica, all four of them grasses. The only totally terrestrial animals are small invertebrates. The largest of these is a wingless fly which measures just a few millimetres in length.
Many animals migrate to Antarctica for the summer. The Arctic tern makes its 9000km journey from the Arctic to the Antarctic each year. Many of the whales migrate southwards when the krill is abundant.
Some animals spend even the winter months in Antarctica. Penguins huddle together in large rookeries to keep warm, as the temperature drops to below -70°C and the winds reach up to 200km/h. These penguins rely on their insulating body fat to keep them warm, as well as the body heat of each other.
The emperor penguins, which spend the winter inland in some of the coldest areas, do not feed at all during the winter. In the spring the female lays one egg which is kept in a special fold of skin over the feet of the male while the female goes to sea to feed. In this way the egg and the chick, once it has hatched, are protected from the cold.
All penguins feed at sea, either on krill or squid. One parent goes to feed while the other one remains in the rookery to protect its young. When the adult returns, it regurgitates some of the food it has eaten in order to feed its chick. The chick taps on the side of its parent's beak so that some food is regurgitated. Many penguin chicks do not survive. Their parents may be killed at sea or perhaps the chicks are too weak to tap on their parent's beak. This is often the case when there are two chicks in the brood. The stronger chick is able to obtain more regurgitated food. Dead penguin chicks are food for the skua. The skuas are scavenging birds which can always be found hovering around penguin rookeries. Skuas will also help themselves to penguin eggs if the eggs are left unattended.
The gentoo and Adélie penguins breed on the uncovered coastal areas during the summer months. Their rookeries are often found on the cliff tops, well away from the reach of leopard seals. These penguins build nests of pebbles and stones. The male penguin is constantly tending the nest. A penguin rookery is a very noisy place. It also has an extremely unpleasant smell due to the enormous quantities of excrement, known as guano.
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