Laboratory spawning, larval development and metamorphosis of the marine snail Nassarius reticulatus (L.) (Caenogastropoda, Nassariidae)

Abstract

Summary The reproduction of Nassarius reticulatus (L.) (Mollusca, Gastropoda, Prosobranchia) was studied in the laboratory, and egg deposition and development through metamorphosis were recorded. Individuals were reared in aquaria to observe the deposition of egg capsules. Animals attached their triangular egg capsules to the glass of a small aquarium. All adult individuals laid several egg capsules in the same area, with the same orientation. Chemoreception may play an important role in the selection of spawning sites for various species of mud snails and our observations confirm this finding for N. reticulatus. Each egg capsule contained 100–120 lecithotrophic embryos, which developed until the veliger stage was reached. The effect of different diets was tested on swimming larvae development. Various phytoplanktonic foods were unsuccessful, as previously observed in other species of gastropods, since the availability of an effective larval food has limited the descriptions of gastropod development in the lab oratory. However, a compound food, a liquid suspension for filter-feeder organisms, allowed us to observe complete larval development and metamorphosis in 35 days. All phases of the larval development were observed, along with their morphology (in light microscopy) and ultra-morphology (SEM). Settled juveniles were fed on commercial granulated food and observed over a period of 45 days.