Curiosity 32: Cone snails

I started reading Anthony Doerr's first book, of short stories, called The Shell Collector, today, and the title story features, somewhat largely, cones, highly venemous snails of the family Conidae. In the story, they both heal the sick, and kill. Or maybe what they're really doing is transforming their prey, from one state to another.

There's a striking passage in the story about the cone snail's bite:

Under a microscope, the shell collector had been told, the teeth of certain cones look long and sharp, like tiny translucent bayonets, the razor-edged tusks of a miniature ice-devil. The proboscis slips out the siphonal canal, unrolling, the barbed teeth spring forward. In victims the bite causes a spreading insentience, a rising tide of paralysis. First your palm goes horribly cold, then your forearm, then your shoulder. The chill spreads to your chest. You can't swallow, you can't see. You burn. You freeze to death.

So of course I had to find out if there are any photographs of these teeth. I found a brief article about the cat cone, or Conus catus, whose harpoon-shaped teeth, 2.5 mm (0.1 in.) in length, look like this:

There's also a diagram of the snail's strike mechanism, which activates fully in less than 100 microseconds (comparable to a bullet being fired from a pistol), but to get a full appreciation for what it means, I refer you to the article. It's just another example of evolutionary amazingness: too wild to have been "invented" over the course of a seven-day period, let's just say.

The reason for all this harpoonal ballistics is to envenomate fish prey. But it's so potent that, in larger species, it can kill a human. One estimate, in fact, is that the venom of just one Conus geographus, the most venomous of the 700–900 or so species of cones, could kill up to 700 people. Maybe that's an exaggeration, but it is certain that this snail isn't something you want to mess with.

Cone snails have long been sought after by collectors for their beautiful shells. One species, Conus gloriamaris, or Glory of the Sea, which can reach a size of 6 inches, was at one point understood to be so rare that it was valued at thousands of dollars and found only in the collections of museums and the very wealthy. In 1969, however, thanks to scuba, it was discovered in its native habitat in larger numbers, so now it goes for only $100 or so. But is still a favored object of collectors.

Here is Conus textile, the textile cone snail, alive:

And here is a selection of cone snails (not to scale)—fish hunters in the top row, snail hunters in the middle, and worm hunters at the bottom (if you want to know their specifics, go here). You can certainly see why they are favorites of shell collectors.

And yes, the venom of cone snails is being investigated for possible medical use, for example as a powerful painkiller—though delivery remains problematic, so morphine will continue to dominate on that front. Still, research continues.

My father often brought me seashells from his travels when I was a kid. I'm sure I have a cone snail or two tucked away in a box in the garage somewhere. Yet another reminder that I need to get in there and do some heavy culling and sorting...