Eggs of Marphysa gravelyi are spawned in gelatinous masses and the developing larvae are harboured in them until they are ready to undergo settlement. In order to understand the function of the jelly mass, morphometric, histochemical, biochemical and antimicrobial analyses were performed. The observations indicate the fibrous jelly mass is composed of carbohydrate, protein and lipid, and size is correlated to number of eggs present within. Extracts from the jelly mass of Marphysa gravelyi exhibit inhibitory activity against Escherichia coli, Vibrio vulnificus and Candida albicans but no activity was seen against seven other microorganisms tested. The results show that the function of the jelly mass is to nourish the developing embryos, protect against desiccation and predation from macrofauna, and most importantly prevent the dispersal of the juveniles from the desirable habitat.
