PRELIMINARY INVESTIGATION ON THE PHYSIOLOGY AND ECOLOGY OF LUMINESCENCE IN THE COPEPOD, METRIDIA LUCENS

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Abstract
The maximum recorded intensity of the luminescent flash was 1.2 x 10-3 [mu]w/cm2 at 18 cm. Duration of flashes greater than 10-4 [mu]w/cm2 ranged from 3-50 seconds. The peak of the luminescence spectrum occurred at 482 m[mu] with half maximum intensity between 440 m[mu] and 525 m[mu]. The ability to luminesce on stimulation was largely unaffected by prolonged laboratory culture. The luminescenl response was not affected by light and there is no apparent daily rhythm. The latent period between stimulus and response was 8-10 msc. The period from stimulus to maximum response varied from 20 to 60 msc. Metridia lucens did not demonstrate spontaneous luminescence except in the presence of planktonic predators, most notably Meganyctiphanes norvegica. When a group of Metridia were kept with a Meganyctiphanes, the number of flashes produced by the copepod was always greater than the number of copepods eaten by the euphausiid, suggesting that the flashing may have survival value.