Settlement and metamorphosis of Rapana venosa (Gastropoda: Muricidae) with implications for artificial culture

Abstract

The rapa whelk Rapana venosa transforms from a phytophagous larva to a carnivorous juvenile after settlement and metamorphosis. The high mortality rate and low metamorphosis rate (<1%) of larvae are among the key factors limiting the recovery of the resources of R. venosa. We studied these two processes and showed that the larva has the ability to settle and metamorphose in the middle and late 4 spiral whorl period, and the use of substrates (scallop shells with oysters) can significantly improve the settlement and metamorphosis rate of larvae. The presence of darkness, juvenile bivalve shellfish, and oyster polysaccharide could effectively increase the rates of larval settlement and metamorphosis. Our findings broaden the understanding of settlement and metamorphosis in gastropods and can be used to improve population control, resource recovery and commercial breeding strategies for R. venosa.