The mechanical triggering of bioluminescence in marine dinoflagellates: Chemical basis

In both photosynthetic ( Pyrodinium bahamense, Gonyaulax polyedra, Pyrocystis Iunula, P. noctiluca, P. fusiformis ) and nonphotosynthetic ( Noctiluca miliaris ) bioluminescent dinoflagellates chemical stimulation can by‐pass mechanical stimulation. The effective ions are Ca ++ , K + , NH 4 + and H + . Other chemicals found effective are those implicated in Ca ++ transport or binding. There are interspecies differences in degrees of mechanical and chemical stimulability. Photoinhibition of mechanical stimulability is the result of two effects, the first a reduction in total bioluminescence potential and the second a decrease in mechanical stimulability resulting experimentally in a decreased rate of light emission. This latter effect can be reversed with Ca ++ ions. Chemicals which bind Ca ++ or displace Ca ++ can mimic the effects of photoinhibition. The chemical inhibition of mechanical stimulability is also reversed by Ca ++ ions. A scheme is proposed which is consistent for all species examined.