We may not think much of them when we see a snail or slug ambling across the garden path, but you may be shocked to learn that one of the most venomous beasts on this planet is in fact a snail. Admittedly you’re unlikely to encounter it in your shrubbery, but the Cone snail, which is a marine species of the gastropod, boasts a venom that makes it a fearsome predator and a serious threat to humans, too.
The Cone snail name covers over 600 species, and they are mostly found in warmer, tropical waters, making their homes near coral reefs or buried in the ocean floor. These fearsome beasties are carnivorous, hunting and consuming small fish, marine worms, and even sometimes other Cone snails. Unlike their benevolent land-based cousins, the Cone snail is well armed. They can shoot a hollow, barbed tooth, much like a harpoon, at their prey and then inject the unfortunate victim with powerful nerve agents called conotoxins. This nasty venom instantly paralyses the fish or worm, giving the snail time to ingest their meal at their leisure.
Humans versus molluscs
Those harpoon teeth can be used for defence, as well, which makes them a danger to humans. Cone snails’ shells tend to be attractively coloured or patterned, so often they are picked up by unsuspecting divers who will get a dose of venom for their curiosity. The muscular spasm that fires the darts is so strong that they can penetrate wetsuits and cause a real problem for people. After a Cone snail sting, the victim might experience immediate pain, numbness and tingling, or it could be delayed by days. In severe cases stings from the larger species can result in paralysis and respiratory failure causing death. Indeed, the Conus geographus snail, which consumes mostly fish, is nicknamed the ‘cigarette snail’, implying that you would only have time to have a smoke before the venom killed you.
Hard as snails
On land, even without harpoons, snails can still pose a threat. The Giant West African snail might look like a huge charming creature, but as an invasive species it can cause major damage to agriculture as a vector for diseases, while also chowing down on native plants. Worse still, it is a carrier of lungworms, which can be fatal for curious dogs and cats that bite on them, and can be a cause of meningoencephalitis in humans. The Roman snail, common to our forests, don’t have venom or poison, but have an ingenious defence from insect attacks – they produce a foamy mucus to keep enemies at bay, drowning ants and other attackers.
The plus side for us humans is that the Cone snail’s venom has been used to produce pharmaceuticals because of its amazing potency. The painkiller Ziconotide, which is 1,000 times more effective than morphine, was first sourced from the Magician Cone snail. There are even trials using that venom to treat Alzheimer’s and Parkinson’s diseases. A little slime and an occasional sting might just be worth it after all!