Antarctic krill (
Euphausia superba) is a
species of
krill found in the
Antarctic waters of the
Southern Ocean. It is a small, swimming
crustacean that lives in large schools, called
swarms, sometimes reaching densities of 10,000–30,000 individual animals per cubic metre. It feeds directly on minute
phytoplankton, thereby using the
primary production energy that the phytoplankton originally derived from the sun in order to sustain their
pelagic (open
ocean)
life cycle. It grows to a length of , weighs up to , and can live for up to six years. It is a key species in the Antarctic
ecosystem and is, in terms of
biomass, probably the most abundant animal species on the planet (approximately 500 million tonnes).