Portal:Crustaceans/Selected article/5

Krill is a shrimp-like marine invertebrate animal. These small crustaceans are important organisms of the zooplankton, particularly as food for baleen whales, manta rays, whale sharks, crabeater seals, other seals, and a few seabird species that feed almost exclusively on them. Krill occur in all oceans of the world. They are considered an important trophic connection – near the bottom of the food chain – because they feed on phytoplankton and to a lesser extent zooplankton, converting these into a form suitable for many larger animals for whom krill makes up the largest part of their diet. In the Southern Ocean, one species, the Antarctic krill, Euphausia superba, makes up an estimated biomass of over 500 million tonnes, roughly twice that of humans. Of this, over half is eaten by whales, seals, penguins, squid and fish each year, and is replaced by growth and reproduction. Most krill species display large daily vertical migrations, thus providing food for predators near the surface at night and in deeper waters during the day.