Studies of venom ontogeny, biomechanics and morphology of the prey-capture mechanism of predatory snails in the genus Conus . Mike Salisbury

Abstract

The venomous gastropods in the genus Conus evolved to more than 500 species in a time span of 50 million years. During this time, cone snails radiated into three generalized groups: fish-hunters, worm-hunters, and mollusc hunters. This rapid rate of diversification is most likely linked to the development of a unique prey capture mechanism. There is some evidence to support that fish hunting cones feed on worms in a juvenile stage then convert to a piscivorous diet. This suggests that venom profiles would be post-metamorphically modified from one diet preference to another. Current research investigates this ontogenic change in venom sets by the rearing of Cones in the laboratory. A specialized circular flow aquarium (Kreisel) was utilized along with algal cultures of Isochrysis and Phaedactylum to simulate natural oceanic environment for larvae. As adults, it has been shown that in at least one species, Conus catus , the snails balistically propel a hollow spear through a proboscis into their prey, which then acts like a hypodermic needle to inject specialized venom peptides. Using specimens of C. catus , current research attempts to investigate the cellular components contributing to prey-capture. To gain better understanding of the biomechanics involved in this mechanism, Conus pennacues is recorded during prey-capture using high speed video. A juvenile C. pennaceus makes for an ideal model to study this process because of its translucent proboscis and venom granules facilitating easier observation of venom dynamics. Observations suggest pressurization behind a medial sphincter, followed by rapid expulsion into its prey.