How to recognize a Calocalanus female:

Using a binocular :

A1 much longer than boby (often broken)

3 or 4 visible thoracic segments.

Urosome 2 or 3-segmented.

The genital segment is ball shaped in dorsal view.

2 setae on the furca are much thicker than the others (often broken).

Using a microscope :

P5 is rather small, uniramous and symmetrical.

How to differenciate C. styliremis from other Calocalanus

Using a binocular :

3 visible thoracic segments.

Urosome short, 3-segmented.

Furca is divergent.

(Notes that body shape is very variable in this species.)

Using a microscope :

P5 3-segmented, with one long spine (slightly longer than the 3 segments together) and several spinules at the end of the third segment (see figures).

Ecological Notes :