Cyclops scutifer is the most common planktonic copepod in Norwegian lakes, and is also found in the high mountain. The two last segments of the thorax are characterized by having a highly pointed appearance.

Key characteristics

Based on habitual criteria Cyclops scutifer can easily be distinguished from other Cyclops species by the highly pointed appearance of the two last segments of the thorax. Another criterion used to distinguish C. scutifer from its relatives is the appearance of the seta attached to the 1. basal segment of the 4. pair of legs. This is much coarser in C. scutifer and C. insignis than in other Cyclops species. The body of C. scutifer is highly pellucid and generally almost colourless, but in some cases it exhibits a beautiful emerald green or red hue.

Female: Length 0.9–1.6 mm

Male: Length 0.8–1.0 mm

Ecology and distribution

C. scutifer is the most common planktonic copepod in Norwegian lakes and is found in nearly 60 % of the water bodies where zooplankton is sampled. It occurs with a high frequency at all elevations, also above 1000 m a.s.l., and is the only species recorded from a lake situated 1835 m a.s.l. In lakes <1 ha the chance to find C. scutifer is less than in lakes above this size. C. scutifer is weakly acid sensitive, and occurs with its highest frequency when pH is between 5.0 and 7.5. The frequencies of lakes with C. scutifer decrease when the content of electrolytes is high (>10 mS/m).

    Høyde over havet (moh.)|Elevation (m a.s.l.)
    Vitenskapelig navn < 100 100-299 300-499 500-699 700-999 >1000
    54 53,8 73,8 67,1 64,9 46,9
    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
    0 2 23,1 55,3 72,5 67,2 56,3
    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
    59 61,2 65,7 72,4 72,2 75,4 71,4 59,5 35,6
    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
    30,2 39,5 52,5 67,3 62,5 61,9 67,7 53,9

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