Megacyclops viridis is a robust species but is somewhat smaller than its close relative M. gigas. It is found all over the country from see-level to above tree line, being most common in small nutrient rich ponds.

Key characteristics

Megacyclops viridis is the smaller of the two species that belongs to the genus Megacyclops in Norway. Compared with species in the genus Cyclops, their body is somewhat more robust and P5 (last pair of legs) are very characteristic. M. viridis is distinguished from M. gigas by the length of the inner seta of the tail, which in M. viridis is more than twice as long as the outer seta. The furca itself is shorter than in M. gigas. Its colour is variable, including bluish green and olivaceus as the most common colours.

Female: Length 1.2–1.3 mm

Male: Length 1.0 mm

Ecology and distribution

M. viridis is a common littoral copepod found in about 13 % of the localities. It has a scattered distribution and occurs from sea level to 1396 m a.s.l., with the highest frequency below 300 m a.s.l. It occurs in water bodies of all sizes, though ponds with a surface area <0.1 da, seems to favour the species (>18 %). M. viridis is tolerant to pH (4.5–9.9) and occurs in both electrolyte poor and electrolyte rich water, being most common in the latter.

    Høyde over havet (moh.)|Elevation (m a.s.l.)
    Vitenskapelig navn < 100 100-299 300-499 500-699 700-999 >1000
    15 22,7 8,2 5,1 4,8 6,7
    Innsjøareal (da)|Surface area (da)
    Vitenskapelig navn < 0,01 0,01 - 0,09 0,1 - 0,9 1,0 - 9,9 10,0 - 99 100 - 999 > 1000
    17,6 23,9 9,1 12 10,8 15,6 19,6
    Ledningsevne (m S/m)|Conductivity (m S/m)
    Vitenskapelig navn < 1,0 1,0 - 1,4 1,5 - 1,9 2,0 - 2,9 3,0 - 3,9 4,0 - 4,9 5,0 - 6,9 7,0 - 9,9 > 10,0
    5,5 7,1 8 11,7 10,7 12,3 11,8 25 30,4
    pH
    Vitenskapelig navn < 4,5 4,5 - 4,9 5,0 - 5,4 5,5 - 5,9 6,0 - 6,4 6,5 - 7,0 7,0 - 7,4 > 7,5
    0 9,9 11,7 13,1 18,5 13,8 12,4 19

Look alikes

Megacyclops gigas