Insights into the origins of fish hunting in venomous cone snails from studies of Conus tessulatus

Only rarely is it possible to reconstruct molecular events that trigger the radiation of new lineages. Here we report key evidence that allows reconstruction of the transition from worm hunting to fish hunting among the species-rich family (Conidae) of marine cone snails (>700 species), which resulted in the emergence of multiple biodiverse piscivorous clades. A priori, the evolution of fish-hunting specialists would seem extremely improbable in a lineage of slowly moving snails that cannot swim, unlike their fish prey. The combination of results from molecular neuroscience, phylogenetic analysis, and chemical biology demonstrates that an ancestral cone snail venom peptide similar to δ-conotoxin TsVIA, a defensive venom component, preadapted a worm-hunting cone snail lineage, enabling the shift to a piscivorous lifestyle.