Metridia longa (Lubbock, 1854)
A common vertially migrating copepod of the Arctic
Size
- Eggs 0.16 mm
- Females 2.25-3.0 mm prosome, 3.7-5 mm total length
- Males "one stage" smaller (prosome 1.75-2.2)
Color & Characteristics
- Body colorless and nearly transparent
- Lipid sac small
- Urosome (tail) long (~ 65% of prosome), with only 3 segments in female (5 in male)
- Antennae longer than prosoem, less than total length, with stout spikes on leading edge of basal segments
- Mouth parts heavier than a typcial filter-feeder
Habitat
- Predominantly arctic, northern North Atlantic
- A deep-water species, abundant on shelf areas deeper than 50 m and throughout deep basins
- Early stages reside below the upper mixed layer
- Later stages and adults are strong diel migator, feeding in surface waters at night, and hiding deeper during day
Feeding
- An omnivorous suspension "filter" feeder on phytoplankton, protists and smaller multicellular zooplankton (eggs, nauplii)
- Feeds activley year-round so limited need for lipid storage
Life cycle
- Reproduces all-year round
- Timing of most active spawning varies in different areas from spring (Norwegian fjords) to late autumn (White Sea, Arctic Ocean)
- Clutch size dependent on size of female with maximums in excess of 150 eggs and typically 60-100 eggs
- Generation length and life expectancy estimated 1 year
Page Author: Russ Hopcroft
Created: Dect 10, 2009
