Etude expérimentale du comportement nuptial de Platynereis dumerilii (Annelida: Polychaeta): chémoréception, émission des produits génitaux

In the heteronereis form of Platynereis dumerilii, the roles of the swelling of the parapodial cirri of the male or female first segments, of the crenellations of the dorsal parapodial cirri of the male posterior region and those of the male pygidial papilli have been ascertained experimentally with respect to nuptial behaviour. The nuptial dance and the release of the genital products are provoked by chemical stimulating discharges from the partner of the opposite sex. The chemical stimuli act on the swelled or crenellated parapodial cirri, probably through the bipolar chemoreceptor neurons which are numerous on these organs. The excitation is transmitted to the cerebral ganglia by way of the ventral cord; it is translated into motor impulses which act upon the musculature concerned in the nuptial dance and in the release of genital products. Accordingly, the swelling and the crenellations of the parapodial cirri appear to contain chemoreceptors. The specificity of this chemoreception, in regard to the exciting substance emitted by the opposite sex, is probably related to the presence of a protein (Boilly-Marer, 1966a, b) elaborated during heteronereidation by epidermal cells adjacent to the dendritic extensions of the chemoreceptor cells. The pygidial papilli appear to insure sperm evacuation.