Rhythmic behaviour that is entrained to the movement of the moon and the tides. The lunar cycle of 29.5 days is known to influence a variety of aspects of behaviour, primarily in marine animals. For example, the palolo worm (Eunice sp.) releases its gametes into the sea only during the neap tides of the last quarter of the moon in October and November. Worms isolated in the laboratory produce their gametes at the correct time, showing that this activity is probably controlled by an endogenous biological clock. Amongst crabs (Brachyura) of various species, the tidal rhythm is superimposed upon a circadian rhythm, resulting in nocturnal activity only when the tide is high.
Subjects: Zoology and Animal Sciences.