This is our experience of electrophysiology with molluscs which might possibly help

Dear John, thanks for the answer. My experience with electrophysiology in molluscs (i.e. being in the same lab while someone else stuck electrodes in slugs and snails!) makes me beleieve that they have much larger neurones than echinoderms. But I will have a look at the papers, nevertheless. We are also trying to do behaviour with these things...(spoken with the arrogance of a vertebrate physiologist). That, at least, seems to be working.

Dear Peter

didn't work with echinoderms but with polychaetes. The article provides a few details on electrophysiology we used to do. The suction electrode work rather well and was more rugged the micro-electrodes. I also remember that we did relax animals with MgCl2 / seawater mix before pinning them down - it may just work on echinoderms, if not try putting them on ice while fixing them.

Dear Carsten,

Thanks for the help; I will give the suction electrodes a try. We tried MgCl2 as anaestheitic, which worked up to a point; they retract their tentacles, where we expect as least some of the chemosensory cells to be. We could try combining this with ice, though. Thanks for the tips.

Peter

Dear Peter,

I have recently used Menthol crystals as anesthetics for different echinoderms, including Holothuroids, which worked well for most specimens. Maintaining the specimens at low temperatures while exposed to the Menthol crystals seemed to assist the anesthetization (at least for tropical/warm-water species). Larger specimens do require exposure times of up to 1.5 hr before reaching complete anesthetization.

Omri

Dear Omri,

Thank you very much for the tip. I had seen that some people were using menthol, but it is good to know that it works with sea cucumbers. I will also be sure to give it some time to work.

Thanks again,

Peter