Weird Wednesdays: The dastardly deadly cone snails of Queensland

The “Weird Wednesday” column is brought to you by a staff writer who is obsessed with factoids, history bits and freaky information to get you over the weekday hump.

A member of the Conus genus, the cone snail are a type of sea mollusk found in the Great Barrier Reef in Australia. (Photo courtesy of Wikimedia Commons)

Of all the marine gastropods that peacefully ooze across the ocean floor, perhaps the most photogenic, and nefarious, would be that within the genus Conus. Though their shells are colorful, and beg collection as you stroll along the sandy beaches of Queensland (like all things in Australia) they are actually horribly venomous and will lead you to an agonizing death if disturbed.

Cone snails are a type of sea mollusk, found in warm, tropical water throughout the world, including the Eastern Cape of South Africa, and the Mediterranean and Indo-Pacific Oceans. They hang around coral reefs, living their carnivorous lives out to the fullest by snacking on marine worms, molluscs, fish and even other cone snails.

Though the snails are eyeless, they’re still able sense the world around them, sort of like a marine, really slow-moving Daredevil. They use a special organ called the osphradium, which is a chemoreceptor organ-- that is to say, it takes in chemicals from the environment and figures out what’s going on based on that. It’s linked to the snail’s respiratory system, which means that as it breathes in, it’s taking in chemicals and materials from the water. In this way the snail can detect silt, food particles and tasty, tasty fish residues.   

The cone snail’s dietary inclusion of fish is the reason for its deadliness. In order for the sluggish snails to take on fast-moving prey, they use a hollow harpoon made of chitin (The same stuff that beetle shells and certain mushrooms are made of) to spear their prey straight-on. The fish is injected with a venom chock-full of neurotoxins, which quickly paralyzes the helpless victim and allows for the snail to dig in (and when I say ‘dig in’ I mean, ‘swallow its still-living, totally paralyzed prey whole’)

All snails have their own hunting methods. Certain species will lie in wait out in the open, shooting out their harpoon (known scientifically as a toxic glosson radula) when prey draws close. Others will burrow themselves in the sand, shooting out their radula from beneath as their unwitting dinner swims blissfully above.

The most famous, and subjectively prettiest, snail of them all is the Conus gloriamaris, known more commonly as ‘Glory of the Sea’. The snail’s whorled, speckled patterns on the shell, however, mislead the deadliness within. Many an unwary tourist walking the coasts of Australia or New Guinea has picked up the spotted shell to admire its patterns, only to be jabbed in the hand with a mix of venoms so complex that an antivenom has yet to be discovered.

Even deadlier is the geography cone, Conus geographus. This gastropod accounts for at least half of all cone snail-caused human fatalities, with enough toxin to kill several adults males in one sting-- making it one of the deadliest, if not the deadliest, animal in the known world.

The symptoms of a cone venom sting seem mild at first, with numbness and a cold feeling originating from the stung area, which soon progresses to a loss of feeling and subsequent paralysis in the limbs. Eventually, once the venom reaches the heart or diaphragm, the patient suffocates as the respiratory system fails, suffers from cardiac arrest as the myocardial tissue paralyses or simply slips into a coma from which they will never wake. The only treatment is to stabilize the patient with life-support equipment until the venom wears off or they expire-- whichever comes first.

The way that the cone’s neurotoxin, known as conotoxin, functions is the subject of much scientific interest. The neurotoxin blocks receptors within the nerves, so that they are prevented from signalling one another, or by blocking calcium and sodium channels in the muscles, which stops them from binding and moving. Once you’re no longer able to signal your muscles or body parts, they stop working all together as paralysis sets in.

Another compound found in conotoxin is, curiously enough, insulin. Conus geographus and Conus tulipa have both been found to use a form of fish insulin in their neurotoxin mixers in order to paralyze the fish through hypoglycemic shock-- the same thing that will kill a diabetic with low blood sugar.

Despite their deadliness, cone shells have been coveted for their shells for centuries. The 18th century saw the advent of shell garden in the Rococo style, driving up the prices of cone snail shells to more than that of a Vermeer painting.

Like Bitcoin and Beanie Babies, however, the market crashed, with several gluts of cone snails being discovered near the Solomon Islands in the 1970s. Nowadays you can get a cone snail shell on the internet for around $9.99 (shipping and handling not included). This goes to show how sensible investing in a snail-based trend really is.  

Be careful as you tread the gorgeous beaches of Australia, dear readers. While you may be on the lookout for spiders and sharks and those nefarious drop-bears, keep in mind that death often hides behind a mask of innocuity.... and beauty.


Marlese Lessing is a staff writer for The Daily Campus. She can be reached via email at marlese.lessing@uconn.edu. She tweets @marlese_lessing.