Odontosyllis at Bermuda and Lunar Periodicity

Abstract

At Bermuda, the polychaete worm, Odontosyllis enopla, approaches the surface and luminesces in connection with spawning monthly after full moon, beginning about 55 minutes after sunset and lasting half an hour. In mid-winter this display was correlated with no moon at that time after sunset irrespective of clouds which did not seem to affect visibility. Response only to decrease in light intensity from sunlight to starlight gives lunar periodicity. There is similar behaviour in other species of Odontosyllis and also in Platynereis and Nereis. Apart from spawning, the prawns Anchistioides and Penaeopsis swarm at the surface in similar fashion, and salmon parr approach the surface most nearly when sunlight decreases to starlight.