Calanus helgolandicus is a copepod found in the Atlantic, from the North Sea south to the western coast of Africa.

[2] Calanus helgolandicus is found in the Atlantic, from the North Sea south to the western coast of Africa.

[3] Calanus helgolandicus is a planktonic herbivore,[8] although it has been shown to eat both dead diatoms and faeces from other members of its species.

This copepod seems to select particles based on their structure; marine snow (which is unstructured), is rejected, whereas dead diatoms and objects such as polystyrene (when given as beads 30 micrometers in diameter) are accepted as food.

[9] Faecal pellets are generally not accepted in whole (possibly due to the difficulty in handling very large particles).