Wikipedia:Today's featured article/July 17, 2005

The Antarctic krill is a species of krill found in the Antarctic waters of the Southern Ocean. They are shrimp-like invertebrates that live in large schools called swarms that sometimes reach densities of 10,000–30,000 individual animals per cubic meter. They feed directly on minute phytoplankton, thereby using the primary production energy that the phytoplankton originally derived from the Sun to their pelagic (open ocean) life cycle. They grow to a length of 6 cm, weigh up to 2 g, and can live for up to six years. They are the key species in the Antarctic ecosystem and are likely, in terms of biomass, the most successful species on the planet.