Conotoxins

Conotoxins are the venom peptides of the cone snails - short chains of ten to thirty amino acids, locked into rigid shapes by sulfur bridges, each one built to fit a single target in a nervous system. A cone snail does not carry a poison so much as a toolkit.

The scale of it is the remarkable part. A single species carries something like a hundred to two hundred distinct peptides, and it does not share that set with its neighbors: every one of the seven hundred-odd cone species has its own. That puts the genus somewhere north of a hundred thousand different compounds, most of them never examined. Some are mixed for speed and fire a fish's nerves all at once so it goes rigid before it can swim; others do the reverse and switch the fish off limp.

Precision that fine is worth a great deal to pharmacology. A peptide from the venom of Conus magus is now a licensed painkiller, delivered into the spinal fluid, roughly a thousand times more potent than morphine and not addictive, because it works on a calcium channel opiates never touch. The same chemistry is why an envenomation by a fish-hunting cone is a medical emergency with no antivenom: there is nothing to make an antivenom against, in the singular.

First aid

Treat any cone snail sting as an emergency, however small the wound looks. There is no antivenom, so everything rests on supporting the person until the toxin wears off.

• Bandage the whole limb firmly, as for a sprained ankle, over the sting and above it, then splint it and keep the person as still as possible. Movement pumps the venom onward.
• Do not cut the wound, do not try to suck the venom out, and do not use a tourniquet.
• Get to a hospital, and keep watching the breathing on the way. If it fails, rescue breaths are the treatment - the toxin does not touch the brain, and a person ventilated through the paralysis can come out of it intact.

Serious stings involve fish-hunting cones, which are also the shells most worth photographing rather than picking up: the harpoon reaches every part of the shell, including the end you would hold it by.