REPRODUCTION OF THE POLYCHAETE GLYCERA DIBRANCHIATA AT SOLOMONS, MARYLAND

Abstract

Field work conducted at Solomons, Maryland, from June 1960 to Feb. 1961, and histological study of material collected in this period have provided data on swarming, epitoky and breeding season of the bloodworm, G. dibranchiata. Swarming occurred during late afternoon on Nov. 5-8. 1960. It covered moderately large areas, but individual worms were widely dispersed. Shedding of gametes is by dehiscence, through the posterior end. Epitokes are characterized by atrophy of the musculature and gut, elongation of the parapods and increase in the number of setae. Evidence indicates that the saccular apparatus of the brain may release a substance to the exterior during swarming. Previous records for Glycera at Solomons suggest the probability of a late spring or early summer breeding period in addition to one in the fall. Temperature and seasonal plankton variations may influence the timing of these reproductive periods. There is also reason to suspect biannual spawning of bloodworms in the Maritime Provinces and Maine.