FAMILY
Euphausiidae
TAXONOMY
Thysanoessa inermis Kroyer, 1846.
OTHER COMMON NAMES
None known.
PHYSICAL CHARACTERISTICS
About 1.2 in (3 cm) long at maturity, weighing about 0.005 oz (0.15 g).
DISTRIBUTION
North Atlantic and North Pacific.
HABITAT
Coastal waters in cool, temperate regions, surface to about 984 ft (300 m) depth. Does not breed above 65–70°N latitude.
BEHAVIOR
Tends to remain near the sea bottom during the winter. Daytime surface swarms may appear during the spring and summer, the result of diurnal vertical migration. Reproduction carried out while swarming.
FEEDING ECOLOGY AND DIET
Primarily feeds on phytoplankton; up to one-third of the diet may consist of copepods, depending on location. In the northeast Atlantic, surveys have found C. finmarchicus to be the dominant prey. Predators include pelagic fish such as capelin as well as larger marine animals.
REPRODUCTIVE BIOLOGY
Spawns in May and June, during the spring phytoplankton bloom. Individuals may participate in two spawning seasons. Lifespan is 2–4 years.
CONSERVATION STATUS
Not listed by the IUCN.
SIGNIFICANCE TO HUMANS
Commercial fisheries off the coast of Japan and in the Gulf of St. Lawrence, Canada.
