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

Richard Herrmann / Pacific Sardine (Sardinops sagax) school feeding on Krill (Thysanoessa spinifera), Coronado Islands, Baja California, Mexico

Richard Herrmann / Pacific Sardine (Sardinops sagax) school feeding on Krill (Thysanoessa spinifera), Los Coronados Islands, Baja California, Mexico

Richard Herrmann / Krill (Thysanoessa spinifera) group, Coronado Islands, Baja California, Mexico

Tony Wu / Small krill on human finger, southern coast of Sri Lanka, Indian Ocean.

Tony Wu / Krill specimen that was spat out by a Blue whale which had just come up from deeper water, Sri Lanka, Indian Ocean.

Tony Wu / Krill specimen that was spat out by a Blue whale, Indian Ocean, Sri Lanka.

Solvin Zankl / Antarctic krill (Euphausia superba) from deep sea Antarctic Ocean.

Norbert Wu / Antarctic Krill (Euphausia superba), Palmer Station, Antarctic Peninsula, Antarctica

Richard Herrmann / Krill (Thysanoessa sp) swarm with diver, San Diego, California

Richard Herrmann / Krill (Thysanoessa sp) swarm with diver, San Diego, California

Richard Herrmann / Krill (Thysanoessa sp) swarm, San Diego, California

Richard Herrmann / Krill (Thysanoessa sp) swarm, San Diego, California

Flip Nicklin / Antarctic Krill (Euphausia superba) a small shrimp-like crustacean critical to the marine food chain, Antarctica

Flip Nicklin / Antarctic Krill (Euphausia superba) a small shrimp-like crustacean critical to the marine food chain, Antarctica

Flip Nicklin / Antarctic Krill (Euphausia superba) schooling, southeast Alaska

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

Hiroya Minakuchi / Antarctic Krill (Euphausia superba), 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) 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) 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) feeding on algae, a small shrimp-like crustacean is the most important zooplankton in the Antarctic food web, 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) pile, 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) schooling underwater, this small shrimp-like crustacean is the most important zooplankton in the Antarctic food web, Antarctica

Flip Nicklin / Antarctic Krill (Euphausia superba) a small shrimp-like crustacean is the most important zooplankton in the Antarctic food web, shown feeding on diatoms which it filters through modified appendages, A...

Flip Nicklin / Diatoms tiny phytoplankton which are food for 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) a small shrimp-like crustacean is the most important zooplankton in the Antarctic food web, shown feeding on diatoms which it filters through modified appendages, A...

Flip Nicklin / Antarctic Krill (Euphausia superba) eggs, close-up, Antarctica

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

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

Flip Nicklin / Diatoms tiny phytoplankton which are food for 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) a small shrimp-like crustacean is the most important zooplankton in the Antarctic food web, shown feeding on diatoms which it filters through modified appendages, A...

Flip Nicklin / Antarctic Krill (Euphausia superba) a small shrimp-like crustacean is the most important zooplankton in the Antarctic food web, shown feeding on diatoms which it filters through modified appendages, A...

Flip Nicklin / Antarctic Krill (Euphausia superba) a small shrimp-like crustacean is the most important zooplankton in the Antarctic food web, shown feeding on diatoms which it filters through modified appendages, A...

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) held by fisherman, 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, a small shrimp-like crustacean is the most important zooplankton in the Antarctic food web, Antarctica

Tui De Roy / Chinstrap Penguin (Pygoscelis antarctica) parent regurgitating Antarctic Krill (Euphausia superba) for chick, Cape Lookout, Elephant Island, Antarctic Peninsula, Antarctica

Norbert Wu / Krill (Stylocheiron maximum) shown along side larger Antarctic Krill (Euphausia superba) deep sea, Eastern Pacific

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

Hiroya Minakuchi / Antarctic Krill (Euphausia superba) at young stage

Martin Camm / Carwardine / Illustration of Antarctic Krill (Euphausia superba), Euphausiidae (Wildlife Art Company).

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) a small shrimp-like crustacean is the most important zooplankton in the food web, Antarctica

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

Luis Quinta / Northern krill (Meganyctiphanes norvegica) shoal, the stomach is coloured red from carotenoids, an indication that this euphausid feeds on copepods, Sesimbra, Portugal, Atlantic Ocean.

Luis Quinta / Northern krill (Meganyctiphanes norvegica) shoal, the stomach is coloured red from carotenoids, an indication that this euphausid feeds on copepods, Sesimbra, Portugal, Atlantic Ocean.

Luis Quinta / Northern krill (Meganyctiphanes norvegica) shoal, the stomach is coloured red from carotenoids, an indication that this euphausid feeds on copepods, Sesimbra, Portugal, Atlantic Ocean.

Frederique Olivier / Krill (Euphausia superba) gathered in an aquarium tank after it was collected by a trawl net

Frederique Olivier / Selecting krill samples (Euphausia superba) from a southern Ocean Trawl onboard icebreaker Aurora Australis

Frederique Olivier / Krill (Euphausia superb) collected in a bucket

Frederique Olivier / Scientists, volunteers and ship's crew observing krill collected onboard the icebreaker Aurora Australis during the 2014-15 marine science voyage, Southern Ocean

Frederique Olivier / Krill collected onboard the icebreaker Aurora Australis during the 2014-15 marine science voyage, Southern Ocean

Frederique Olivier / Scientists and volunteers observing krill collected onboard the icebreaker Aurora Australis during the 2014-15 marine science voyage, Southern Ocean

Richard Sidey / Drone shot of four Humpback whales (Megaptera novaeangliae) bubble-net feeding, cooperatively hunting Krill (Euphausiidae), Antarctic peninsula.

Richard Sidey / Drone shot of five Humpback whales (Megaptera novaeangliae) bubble-net feeding, cooperatively hunting Krill (Euphausiidae), Antarctic peninsula.

Richard Sidey / Drone shot of four Humpback whales (Megaptera novaeangliae) bubble-net feeding, cooperatively hunting Krill (Euphausiidae), Antarctic peninsula.

Richard Sidey / Drone shot of two Humpback whales (Megaptera novaeangliae) bubble-net feeding, cooperatively hunting Krill (Euphausiidae), Antarctic peninsula.