[3] In the cnidarian Hydrichthys sarcotretis, parasitism is taken a stage further when the hydrozoan attaches itself to the C. bellottii.

This is itself an ectoparasite of the northern lampfish (Stenobrachius leucopsarus) in the family Myctophidae.

It will go through five successive postembryonic stages, then only the post-mating females will go into the pericardial cavity of a lanternfish.

Both male and female fish do not reproduce and seem to grow faster when attacked by the copepod and it seems to have a negligible energy demand from them.

[6] The hydrozoan parasite castrates the copepod, a process called hypercastration.