What is a food web?

A food web describes the links between species in an ecosystem. The web is a complex network of food chains. Food chains are often based on plants that provide food for other animals.

Some animals only eat plants and are called herbivores. Others eat plants and animals and are called omnivores. Animals that only eat other animals are called carnivores.

Food webs are finely balanced ecosystems. The loss of even one species can break the delicate threads of the web. This can have a serious impact on the environment.

It starts with krill

In Antarctica and the Southern Ocean, the food web begins with microscopic plants called phytoplankton. These ‘feed’ on the energy of the sun. Phytoplankton are food for Antarctica’s most important species – Antarctic krill.

Krill look like smaller versions of familiar crustaceans such as prawns or shrimp. They are mostly transparent, although their shells have a bright red tinge from small pigment spots. Their digestive system is usually visible and coloured a vivid green from the microscopic plants they eat. They have large black eyes. Adult Antarctic krill are approximately 6 cm in length and weigh over 1 gm.

Who’s eating who?

Nearly everything in Antarctica has krill for dinner. This includes scale fish, squid, and seabirds such as albatross and petrels.

They’re also meals for iconic marine predators including penguins, some seals as well as humpback and blue whales.

Predators can also be prey, with leopard seals eating penguins and other seals. As well as killer whales eating seals and penguins. It’s a tough world!