VIII.—Structure and Biology of the Larva and Spat of<i>Venerupis pullastra</i>(Montagu)

Abstract

Synopsis: This is a study of the structure and biology of the lamellibranch Venerupis pullastra (Montagu) from the early larva to the spat stage. The larva is identified, and the functional significance of the changes that occur during metamorphosis from the larva to the spat is considered. Organ development in the spat up to a length of one millimetre is described. The free swimming larva is studied from the point of view of seasonal abundance, length of pelagic period, vertical distribution and diurnal migration. Spatfalls both on artificial and natural bottom are studied, and the results indicate a possible cause for the high mortality in the early stages of marine invertebrates with this type of reproduction.