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Antarctic food webs

A wide range of plants and animals live in Antarctica. All these plants and animals rely on each other to survive and together make up a food web. 

Even though the water around Antarctica is very cold and often covered with ice, the sea supports a large number of different species from algae to invertebrates to larger vertebrates such as fish, penguins and seals.

Food webs

A food web shows what eats what. It shows how energy flows through the ecosystem. Organisms can be divided into producers, consumers and decomposers within a food web:


Producers in the Antarctic Ocean ecosystem are:

  • sea ice algae - which live on the underside of the sea ice but may fall to the sea floor
  • phytoplankton - which may be carried under the sea ice by currents from open water regions
  • macroalgae - leafy seaweeds and algae that are attached to rocks and corals on the sea floor
  • microalgae - microscopic algae that lives on the surface of sea floor sediments


The plants (producers) are needed by consumers who feed by grazing or filter feeding. Examples include snails, urchins and corals. These consumers in turn will be eaten by other animals such as sea-stars.

At the top of the food web there are larger animals (consumers) such as fish, penguins, seals and whales.


This group of living things break down dead plants and animals for food, releasing nutrients back into the ecosystem. Bacteria are an example of decomposers in a marine ecosystem.

If some animals die due to melting sea ice, it will affect all animals in the food web.

A simple Antarctic food chain

A simple Antarctic food chain.

An Antarctic food web

An Antarctic food web.

This example of an Antarctic food web shows how plants and animals depend upon each other for food. Image: M Pinkerton, NIWA.


Antarctic Krill are a keystone species; what does this mean? Image: Public domain.


Weddell seals are part of the Antarctic marine food web. What trophic level do these seals occupy? Image: LEARNZ.


Organisms in food webs are commonly divided into trophic levels. These levels can be illustrated in a trophic pyramid where organisms are grouped by the role they play in the food web. Image: University of Waikato. 

Do you think all plants and animals in the Antarctic Ocean will be affected by climate change? Find evidence to support your answer.