Distribution
Krill occur worldwide in all oceans, although many individual species have endemic or neritic (i.e., coastal) distributions. Bentheuphausia amblyops, a bathypelagic species, has a cosmopolitan distribution within its deep-sea habitat.
Species of the genus Thysanoessa occur in both Atlantic and Pacific oceans. The Pacific is home to Euphausia pacifica. Northern krill occur across the Atlantic from the Mediterranean Sea northward.
Species with neritic distributions include the four species of the genus Nyctiphanes. They are highly abundant along the upwelling regions of the California, Humboldt, Benguela, and Canarias current systems. Another species having only neritic distribution is E. crystallorophias, which is endemic to the Antarctic coastline.
Species with endemic distributions include Nyctiphanes capensis, which occurs only in the Benguela current, E. mucronata in the Humboldt current, and the six Euphausia species native to the Southern Ocean.
In the Antarctic, seven species are known, one in genus Thysanoessa (T. macrura) and six in Euphausia. The Antarctic krill (Euphausia superba) commonly lives at depths reaching 100 m (330 ft), whereas ice krill (Euphausia crystallorophias) reach depth of 4,000 m (13,100 ft), though they commonly inhabit depths of at most 300–600 m (1,000–2,000 ft). Both are found at latitudes south of 55° S, with E. crystallorophias dominating south of 74° S and in regions of pack ice. Other species known in the Southern Ocean are E. frigida, E. longirostris, E. triacantha and E. vallentini.
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