Venom Facts

Structure of the conotoxin MrVIB found in Conus marmoreus (redrawn from the Journal of Biological Chemistry)Conus marmoreus is an unusual snail in more ways than one.  For starters, it is a carnivorous animal that specifically hunts other molluscs.  Secondly, it utilizes a specialized harpoon-shaped tooth to take down its prey.  Thirdly, it combines a deadly venom secreted through this tooth to positively ensure that its prey cannot escape.  This technique of acquiring food distinguishes the genus Conus from other classifications of snails.  Once the prey has been poisoned, its muscles relax, it becomes flaccid, and it is easy to remove from its shell.

There are approximately 500 known species in the genus Conus, and each have their own distinct venom.  These toxins are aptly named conotoxins.  Conotoxins are small, structured peptide toxins.  This means they are bonded by peptide bonds, which are bonds between the carboxylic end of one amino acid to the amine end of another.  These peptides work by targeting and blocking ion channels of either the voltage-gated or ligand-gated class.  These ion channels are where action potentials in neurons are created.  Therefore, if no ions can get through to the neuron, no action potentials can be made and sent to other neurons, and the prey organism is paralyzed.  It is most likely that different Conus members target different specific ion channels, depending on the animals they feed on.

Conus mamoreus extending its harpoon-holding proboscis (Courtesy of Jeanette and Scott Johnson)For all of the nuances on exactly how these toxins work, visit the article referenced at the American Physiological Society webpage focused on the toxins of the Conus genus.

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