Lethal Snails

July 19, 2015
By Damond Benningfield

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Cone snails are lethal hunters. Credit: Richard Ling 2005, GNU Free Documentation License

The geographic cone snail was already known as a quiet killer. It’s only a few inches long. And like many other species of cone snail, it lurks at the bottom of warm, shallow waters near coral reefs, sometimes burying itself beneath sand and pebbles. It waits until an unwise fish swims close by, then zaps it with a small “harpoon” laced with a powerful neurotoxin. The fish is paralyzed in seconds, ready for the snail to pull it in and swallow it whole.

But according to some recent research, the geographic cone snail has a way to make snagging a meal even easier: It sprays a toxic cloud into the water that can put nearby fish into a coma.

The cloud is laced with high levels of insulin. When a fish ingests the insulin, its blood sugar level drops to dangerously low levels, so the fish goes into a stupor. The snail can then inject the fish with its “stinger” with no resistance at all.

The cone snail has some of the most powerful venom on the planet. It’s a mixture of more than a hundred different toxins. These toxins block the signals that tell the muscles to contract, paralyzing the victim. The geographic snail’s venom is especially potent -- it’s been known to kill people as well as fish.

In recent years, though, scientists have used cone snail venom as the basis for a new set of pain killers. Some of them are a thousand times more powerful than morphine, but they’re not addictive. So a little snail with a painful sting is providing a new way to ease the pain for many people.