Gametogenesis and Breeding in a Natural Population of Nereis Virens

Abstract

Studies of a natural population of N. virens Sars at Southend reveal that the oocytes take a little over a year to mature. After a period of relative quiescence they grow rapidly between September and December and then increase little in size until early May. Within a given specimen small oocytes are more variable in size than large ones. Sperm develop fully from coelomic sperm plates in about eight months, and are mature by the beginning of May. There is a period during which they are characteristically clumped in quartets.