appendages on a Calanoid copepod

Franz Neidl · Post by **Franz Neidl** » Tue Jan 17, 2012 3:34 pm

Sometimes I see Calanoids with appendages on their antenna. I would be grateful if somebody knows the biological function of these appendages and the species name of the copepod.

First picture: Obj. 40x, DIC, stack with 7 pics
Second picture: Obj. 10x, DIC

Franz

BJ · Post by BJ » Wed Jan 18, 2012 11:38 am

Hi Franz,

I think that this may be Calocalanus plumatus, but it is not a species that I have seen.

The consensus seems to be that role of these setae at the end of the antennae is sensing mechanical disturbances. Generally, chemo-sensory organs are concentrated at the base of the antenna, mechano-sensory at the tips and a mixture of the two along the length of the antenna.

The argument for mechano-sensory organs at the end of a long antenna is to isolate them from signals caused by movement of the copepod itself. The sensors then are to pick up movement of prey or predators. I would imagine myself that such a finely detailed structure would be to pick up precise information about small objects close at hand (ie nearby prey) - but I am not a physicist !!

Thank you for posting,

best wishes

Brian

Franz Neidl · Post by **Franz Neidl** » Fri Jan 20, 2012 2:33 pm

Hello Brian,

I thank you very much for your interesting answer. I am really impressed that this calanoid copepod has such a sophisticated kind of "sonar" detection !

Franz