Thysanoessa raschii (Sars, 1864)
A common large multi-relam amhipod of the Arctic
Size
- Eggs & nauplii 0.35-0.45 mm
- Adults 20-25 mm
Color & Characteristics
- Transparent, central body whitish, photophores red
- Eyes round, rostrum pointed
- Anntennae lack lappet, carapace with 1 small denticle
Habitat
- Panarctic and subactic in coastal waters
- Most common in Arctic near Pacific or Atlantic inflows
- Usually above 200 m
Feeding
- Omnivorous, capable of feeding on 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
Life cycle
- Females lay several clutches of eggs (size/number?) during productive spring period
- 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 (typically 13 stages in all)
- Juveniles resemble adults and molt regularly while growing to adulthood over first year of life
- Life expectancy not known, likely 2-3 years
Page Author: Russ Hopcroft
Created: Feb 4, 2009
