Diet, prey narcotization and biochemical composition of salivary glands secretions of the volutid snailOdontocymbiola magellanica

Abstract

Odontocymbiola magellanicais a neogastropod very common in Patagonian shallow waters. It feeds exclusively on molluscs inhabiting the same benthic community. Field studies showed that prey preferences are live gastropods (54%) and bivalves (46%). When no living prey are available they change their trophic behaviour to carrion or cannibalism. Feeding mechanisms observations showed that prey are not asphyxiated by the snail's foot as suggested before for the Volutidae family; they are narcotized by saliva introduced in a cavity made by the foot where prey are immobilized. Saliva is produced by the salivary (SG) and accessory salivary glands (AG) and has a pH around 10, relaxing prey muscles, which are consumed alive. Secretions from AG and aqueous extracts of SG and AG were mainly composed of proteins and glycoproteins, though SDS-PAGE gels revealed that salivary proteins were richer in higher molecular weight bands. Fractionation of secretions from AG on Bio-Gel P-100 yielded only one peak. SDS-PAGE showed that it consisted of only one band (MW 51.3 kDa). Microanalysis of cations showed a higher concentration of calcium and magnesium in the accessory salivary gland. Hypotheses of function of different glands are given in relation to feeding behaviour and anatomy ofO. magellanica.