Jordi Chias / Gentoo penguins (Pygoscelis papua) swimming together and porpoising in search of krill, Antarctic Peninsula, Antarctica.

Jordi Chias / Gentoo penguins (Pygoscelis papua) porpoising, swimming together in search of krill, Antarctic Peninsula, Antarctica.

Steven Kazlowski / Crabeater seals (Lobodon carcinophagus) and seagulls feeding on a school of krill in waters off the western Antarctic Peninsula, Southern Ocean

Ingo Arndt / Antarctic Krill (Euphausia superba) with yellow algae in stomach, a small shrimp-like crustacean is the most important zooplankton in the Antarctic food web, Weddell Sea, Antarctica

Flip Nicklin / Antarctic Krill (Euphausia superba) feeding on algae-covered ice, a small shrimp-like crustacean is the most important zooplankton in the Antarctic food web, Antarctica

Flip Nicklin / Antarctic Krill (Euphausia superba) mass feeding on algae growing on underside of ice, Antarctica

Flip Nicklin / Antarctic Krill (Euphausia superba) a small shrimp-like crustacean is the most important zooplankton in the Antarctic food web, Antarctica

Flip Nicklin / Antarctic Krill (Euphausia superba) mass, Antarctica

Flip Nicklin / Antarctic Krill (Euphausia superba) crustacean, Antarctica

Flip Nicklin / Antarctic Krill (Euphausia superba) schooling underwater, this small shrimp-like crustacean is the most important zooplankton in the Antarctic food web, Antarctica

Flip Nicklin / Antarctic Krill (Euphausia superba) feeding on algae-covered ice, Antarctica

Flip Nicklin / Antarctic Krill (Euphausia superba) group, a small shrimp-like crustacean is the most important zooplankton in the Antarctic food web, Antarctica