Euphausia

Euphausia is a genus of krill in the family Euphausiidae, within the order Euphausiacea. The genus contains numerous species, among the most well-known are Euphausia superba, the Antarctic krill, and Euphausia pacifica, the Pacific krill. Members are small, shrimp-like crustaceans that inhabit pelagic waters.

Distribution and habitat: Euphausia species are found in oceans worldwide, from polar to temperate regions. They are abundant in the Southern Ocean where many dense swarms form. They inhabit open water and contribute to the zooplankton layer, often undertaking diel vertical migration to feed on phytoplankton near the surface.

Biology and ecology: Most species are holoplanktonic, measuring a few centimeters as adults. They feed mainly on phytoplankton and organic detritus, using specialized feeding appendages to filter particles. Krill form large schools that serve as a major food source for many predators, including fish, seabirds, and whales. They are a key link between primary production and higher trophic levels.

Human use and conservation: Antarctic krill (E. superba) is harvested commercially to produce fishmeal, aquaculture feed, and krill oil supplements. Harvest levels are managed under international agreements to balance ecological importance with fisheries, but climate change and predation by fisheries can impact ecosystems. The genus remains a focus of marine ecological research.