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+, NH4+ 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.