Strategy for rapid immobilization of prey by a fish-hunting marine snail.

Some venomous animals capture prey with remarkable efficiency and speed. The purple cone, Conus purpurascens, uses two parallel physiological mechanisms requiring multiple neurotoxins to immobilize fish rapidly: neuromuscular block, and excitotoxic shock. The latter requires the newly characterized peptide kappa-conotoxin PVIIA, which inhibits the Shaker potassium channel 2-4, and beta-conotoxin PVIA5, which delays sodium-channel inactivation. Despite the extreme biochemical diversity in venoms, the number of effective strategic alternatives for prey capture are limited. How securely prey is initially tethered may strongly influence the venom strategy evolved by a predator.