The cold desert is inhospitable to life. The valleys in the interior of Antarctica and the snowy tops of high mountains cannot support life: birds or insects may visit there, but the cold keeps plants from growing. Without plants, there can be no animals because there is nothing for animals to eat.

     The shores of both the arctic and the antarctic have animals that find their food in the ocean. The waters of the antarctic support plankton, which includes unicellular plants. These tiny plants photosynthesize during the antarctic spring and summer, and become the primary producers of a food chain that nourishes animals on land as well as in the sea. This is the first trophic level of this system.

     Food production in this system varies with the seasons. In winter, when the south pole is in darkness, there is no light for photosynthesis, and so no plant growth. In spring, deep ocean currents bring up nutrients from the ocean bottom, and the plankton grows rapidly with both light and food. The animials that live on it grow and reproduce. Later in the year there are fewer nutrients, and growth slows. Some of the animals swim away to areas with more food.

     We will look at this system in the spring, when there is lots of food The plankton provides food for the next level of life forms.

     Tiny animals, such as krill (a kind of tiny shrimp) and very small fishes, feed on the plankton. They become the primary consumers, taking on the role of herbivores and becoming the second trophic level of this system.

     It is difficult to imagine how rich these waters are. They are so full of living creatures that they are almost a soup! The third trophic level, the carnivores, includes larger fishes, squid, seals, penguins, and huge whales, such as baleen whales, that eat enormous numbers of the krill.

     Seals and penguins come onto land to reproduce, but are otherwise well-adapted to life in the ocean. They find all their food in the water. In the water they also become prey for the Killer Whale, the top predator in this biome. Killer whales are tertiary consumers, and occupy the fourth trophic level.

     This diagram shows how the Kilocalories move up the food chain at this time. Remember, we are looking at spring with abundant food here. In another season there will not be so much energy available to distribute.