Krill

The krill (Euphausia superba), a small shrimp like crustacean is the most important zooplankton species associated with the sea ice and plays a key role in the Antarctic food web. Krill occurs in groups or large swarms and occupies a niche similar to that of the herring in the North Atlantic, since large schools of pelagic fish are absent. They attain a size of 6 cm and feed primarily on phytoplankton or sea ice algae. Its feeding apparatus is built to filter phytoplankton out of the water column and to scrape algae from the ice. Apart from frequenting the sea ice to feed, krill in particular juveniles, seek protection from predators in the many nooks and crannies formed by the deformed sea ice floes. Krill is the staple food of many fish, birds and mammals in the Southern Ocean. The biomass of Antarctic krill is considered to be larger than that of the earth's human population and krill swarms can occupy an area equivalent to that of the Andorras.