Annual reproductive cycle of the marine pulmonate, <i>Onchidium verruculatum</i> (Cuvier) and its control by environmental factors

Abstract

Annual reproductive cycle of the proteandric hermaphrodite marine pulmonate, <i>Onchidium verruculatum</i> has been studied with seasonal changes in gonad and accessory sex organ indices and histology of the gonad. <i>O. verruculatum</i> breeds during December to March. Through the development is protendric it becomes simultaneous hermaphrodite during the reproductive peak. Life span of <i>O. verruculatum</i> seems to be 1 year and hence the population exhibits asynchrony in the reproductive status during the postbreeding season. In July to September, slugs with the mature male phase reproductive system are abundant in the population. At the same time older slugs exhibit degeneration of all the sexual cells.Increase in the photoperiod stimulates male maturation whereas increase in temperature during summer terminates the breeding season.