Thysanoessa raschii (M. Sars 1864)

The most widespread Arctic krill

Transparent, yellowish if rich in lipids, females might develop blue hue when spawning; Eyes round, rostrum pointed, photophores red; Anntennae lack lappet, carapace with 1 small denticle; abdomen without keel-spines

Panarctic and subarctic in coastal waters (above 200m); Can be abundant in coastal embayments; Most common in Arctic waters near Pacific or Atlantic inflows, uncommon in central basins; Undergo diel vertical migrations, spending daytime near bottom, night-time in surface waters

Females lay several clutches of eggs during summer; Females require repeated mating after each molt to form new egg clutches; Life cycles is typcial: eggs, nauplius, metanauplius, followed by several stages of feeding calytopsis, and furcillia larvae; Juveniles resemble adults, and molt regularly while growing to adulthood over the first year of life; Life expectancy not known, likely 2-3 years

Primarily herbivourous, may feed on detritous when food is scarse - known to feed directly on under-ice algae; During open-water periods feed on phytoplankton when abundant (shifting to small zooplankton when phyoplankton less abundant); An important prey item for fish, birds, seals and whales