Sex Reversal in the Syllinae (Polychaeta: Annelida)

Among the syllidians, most of the Syllinae reproduce by stolonization. Sexualization, in both the male and female occurs in a certain number of posterior segments, the number being relatively constant for each particular species and in direct relationship to the total numbers of segments in each animal (Durchon, 1959). This sexualized posterior part later develops a head, undergoes a series of muscular modifications, and acquires swimming chaetae on each parapod. These form the stolon which, ultimately, breaks away from the earlier part or stock, thus freeing the gametes at spawning time, and then dies. The stock later re-develops and is capable of further stolonizations.