''Thysanoessa raschii'', sometimes known as Arctic krill, is one of the most common

euphausiid Krill ''(Euphausiids)'' (: krill) are small and exclusively marine crustaceans of the order Euphausiacea, found in all of the world's oceans. The name "krill" comes from the Norwegian word ', meaning "small fry of fish", which is also often a ...

species of the

subarctic The subarctic zone is a region in the Northern Hemisphere immediately south of the true Arctic, north of hemiboreal regions and covering much of Alaska, Canada, Iceland, the north of Fennoscandia, Northwestern Russia, Siberia, and the Cair ...

and

Arctic The Arctic (; . ) is the polar regions of Earth, polar region of Earth that surrounds the North Pole, lying within the Arctic Circle. The Arctic region, from the IERS Reference Meridian travelling east, consists of parts of northern Norway ( ...

seas. They may reach long, and are

sexually mature Sexual maturity is the capability of an organism to reproduce. In humans, it is related to both puberty and adulthood. ''Puberty'' is the biological process of sexual maturation, while ''adulthood'', the condition of being socially recognized as ...

above . ''T. raschii'' is a major prey item of several taxa, planktivorous fishes and

marine mammal Marine mammals are mammals that rely on marine ecosystems for their existence. They include animals such as cetaceans, pinnipeds, sirenians, sea otters and polar bears. They are an informal group, unified only by their reliance on marine enviro ...

s. It is also a common prey item of

seabird Seabirds (also known as marine birds) are birds that are adaptation, adapted to life within the marine ecosystem, marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent ...

s, including

shearwater Shearwaters are medium-sized long-winged seabirds in the petrel family Procellariidae. They have a global marine distribution, but are most common in temperate and cold waters, and are pelagic outside the breeding season. Description These tube ...

s. This species goes through a number of stages in its development. Roderick Macdonald defined the characteristics of fourteen stages, or 'furcilia'.

References

Krill Crustaceans described in 1864 Taxa named by Michael Sars {{Malacostraca-stub