What is the role of krill in the Antarctic food web?

Krill are very small crustaceans of the sea that eat even smaller creatures, called phytoplankton. Krill are called a keystone species because they provide food for a large number of larger animals. If the krill were to disappear, so would all the creatures that eat them. The animals that eat krill are baleen whales, manta rays, whale sharks, many species of seals, fish, and seabirds.