The Spawning of Arenicola Marina (L.) II. Spawning Under Experimental Conditions

Abstract

Macerated tissues of whole Arenicola marina, when injected into the body cavity of male worms, induce spawning after a prolonged latent period of, generally, 60—90 min. The nature of the spawning reaction is described. Emulsified tissues were submitted to heat, ultra-filtration, extraction by fat solvents and saponification. The technique is described whereby the products of these treatments were assayed for potency in inducing the spawning of male worms. The active substance proved to be a lipid and upon rigorous saponification the fatty-acid fraction was found to induce shedding, but the unsaponifiable fractions failed to do so. The active substance was also found to be a normal tissue constituent of male, female and immature worms, but it is concentrated in the gut and coelomic contents. Tissue extracts appear to induce spawning primarily by the breakdown of the sperm morulae in the coelom to free spermatozoa, but there may also be some modification of the action of the nephromixia. It is suggested that the active substance found in the tissues provides the ‘internal stimulus’ by which spawning is normally induced. Evidence for this suggestion is that it is derived from the tissues of the worm and that it appears to be a specific chemical fraction of the tissues which is effective. In addition, tissue extracts induce a normal spawning reaction and there appears to be a relationship between the temperatures at which the active substance is most potent in inducing shedding in the laboratory and those prevailing on the shore during the breeding season. The possible mode of release of the active substance is discussed.

Distribution of dry matter between the tissues and coelom inArenicola marina(L.) equilibrated to diluted sea water

“…An alternative explanation derives specifically from the fact that the worms analysed in the present study were approaching sexual maturation, and the transfer of material from the coelom appears to be associated with the presence of developing genital material within the coelomic cavity. It has been shown by Howie (1961a) that the ciliated funnels of the nephromixia in A. marina must reject the gametes during their development in the coelom, and that the movement of the ripe germ cells from the body cavity is influenced by substances which can be extracted from the tissues of the worm. Of all the tissues from which extracts were made, the most potent substances were obtained from the gut and coelomic contents.…”

The role of a fatty acid hormone in the reproduction of the polychaeteArenicola marina(L.)

“…In males, this results in the presence of clusters (morulae) of filly differentiated spermatozoa that are held as a syncitiurn (Howie, 1961a;Meijer, 1979b;Bentley and Pacey, 1989;Pacey and Bentley, 1992) until the endocrine signal, which causes the dissociation of these sperm morulae to free sperm and spawning that follows, is received (Bentley, 1985). There is substantial evidence that the endocrine signal in males is a 20 carbon polyunsaturated fatty acid (8,11,1 4-eicosatrienoic acid) termed the sperm maturation factor (SMF) (Bentley, 1985;Bentley et al, 1990), and the same substance is responsible for both sperm activation and spawning .…”

Sex pheromones in marine polychaetes:volatile organic substances (VOS) isolated from Arenicola marina

“…For use in assays, aliquots of these stock sobreakdown-inducing hormone remains unknown but lutions were diluted 100-fold to give a final concentraprogress has been made recently in the identification tion of 10-4 M. Females were injected with prostomium of the male spawning hormone. The active compound homogenate (1 prostomium equivalent per female) that activates spermatozoa of males and initiates the which causes spawning in fully mature specimens release of the spermatozoa is a polyunsaturated fatty (Table 1) (Howie 1961a, b, Pacey & Bentley 1992). acid, 8,11,14-eicosatrienoic acid (Bentley et al 1990, Extraction and analysis of volatile organic subPacey .…”