Unexpected Deadly Beauty

Marbled cone snail (Conus marmoreus) by shadowshador

In olden days, in Australia, young healthy beachgoers were sometimes found lying on the shore dead.  Their bodies gave no evidence of trauma, indeed they had not even gone into the water. Something just struck them down as they sauntered along the beach.  It was not until 1936 that the mysterious killer was finally revealed when a beachcomber picked up a colorful snail and began to scrape its shell with his knife.  The unlucky young man uttered a cry as the snail somehow pricked him.  He then fell down, went into a coma, and shortly died.  Because of witness testimony, coroners knew what to look for and they removed a tiny poisonous harpoon the size of a small hair from the victim’s hand. The culprit turned out to be a cone snail, one of a diverse group of deadly gastropod mollusks.

The Geographic Cone Snail (Conus geographus) shows its siphon and proboscis. This snail is also humorously called “the cigarette snail” since if one stings you, you allegedly have time for one cigarette before dying.

There are over 600 different species of snail within the genus Conus and they are all poisonous predatory hunters.  The smaller cone snails hunt tiny mollusks and worms but the larger snails feed on fish, which need to be quickly subdued (so that they do not injure the snail by thrashing about) and then consumed with equal dispatch so that other ocean creatures do not steal the meal.  In order to quickly dispatch their prey (and defend against larger predators), Cone snails have a sophisticated weapon–a modified radula tooth which directly injects potent venom by means of a tiny harpoon-like “dart.”  The snail finds prey by carefully testing/sniffing the water with a siphon.  It then stretches out a long flexible proboscis and fires the disposable hollow radula tooth (filled with venom) into the prey by means of a powerful muscle contraction.  Below is a shocking film which shows a cone snail killing and consuming a clown fish by such means.  It is not for the faint of heart!

Although cone snails are obviously alarming to divers and shell collectors (particularly in warm tropical reefs where the large poisonous specimens live), the potent cocktail of neurotoxins utilized by the creatures is of great interest to pharmaceutical researchers.  Since each species of cone snail has a very large number of different “conotoxins” in its poison, scientists have been struggling to catalog and understand the dangerous mixtures. These conotoxins are generally peptides which interfere with the ability of nerve cells to communicate with one another.  Not only might such chemicals provide the key to curing neurodegenerative diseases and brain cancers,  conotoxin research is now the most promising avenue towards effective medications to deal with certain sorts of chronic pain.

A lovely diagram of Conotoxin Peptides from “The Journal of Neuroscience”

Unfortunately all of this research has not provided any effective antitoxins for victims of cone snail stings.  If a person is fully darted by one of the large poisonous specimens, their best hope is to go on a ventilator until their body expunges all of the poison—an uncertain prospect at best.

A Tiny Sample of the Exquisite Variety of Cone Snail Shells (Photo by Pet/Wikimedia Commons)

Many cone snails have beautiful colorful shells marked with vivid abstract patterns.  Some of the most valuable shells ever came from cone snails–which continue to fascinate conchologists and shell collectors.  Even today divers and beach combers are sometimes overwhelmed by the beauty of cone snails and reach out to grab the lovely creatures.  Hopefully this article has convinced you that doing so is a very bad idea.

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