Spawning periodicity and habitat of the palolo worm Eunice viridis (Polychaeta: Eunicidae) in the Samoan Islands

The relationship between the phase of the moon and the emergence of the epitokous segments of the palolo worm E. viridis Gray has been known to the natives of the Samoan Islands for centuries. The author's own investigations concern the occurrence of the worms in the reef, in which they gnaw long tunnels through the massive blocks of coral limestone at levels characterized by the occurrence of symbiotic algae. The casting off of the epitokous segments occurs at the third quarter of the moon in October or November. An analysis of known dates on which the swarms of worms have appeared permitted a precise method of prediction to be formulated. The causality of this periodicity is discussed.