SEX-PHEROMONES IN MARINE POLYCHAETES .5. A BIOLOGICALLY-ACTIVE VOLATILE COMPOUND FROM THE CELOMIC FLUID OF FEMALE NEREIS (NEANTHES) JAPONICA (ANNELIDA POLYCHAETA)

In Nereis japonica, mature individuals leave their burrows to spawn at night near to the water surface. This process is timed by environment al factors such as temperature, daylength and lunar cycle to result in simultaneous spawning of a given population. The swarming behaviour w hich ensues is controlled by a bouquet of sex pheromones. A volatile c ompound, the ketone 3,5-octadiene-2-one was isolated and chemically ch aracterized from the coelomic fluid of ripe, swarming females of N. ja ponica. During the reproductive behaviour of this species the ketone e licits an increase of swimming activity. This nuptial dance is charact erized by swimming in circles prior to the release of gametes into the free water column. In N. japonica, the 3,5-octadiene-2-one functions in a very similar way to the sex pheromone 5-methyl-3-heptanone previo usly described in a number of nereid species. 5-methyl-3-heptanone is not detectable in N. japonica and behavioural assays revealed no signi ficant stimulation by addition of this substance but an abrupt decreas e in swarming activity. The importance of species specificity of chemi cal signals during reproduction of closely related nereid polychaetes is discussed.