This Snail’s Venom Mimics Pheromones to Lure Prey With Sex

The mini mollusk may use a ‘siren call’ strategy to entice marine worms out of hiding

A white, orange and black snail shell sits on a black table
Shallow-water imperial cone snails collected for the study were generally larger than the snails collected in deeper water, suggesting they may be separate species. Photo by Samuel S. Espino

There are over 700 species of cone snails, and they all pack an overwhelming array of venoms to immobilize their prey, from paralyzing neurotoxins to insulin-imitating molecules. New research shows that they have another trick up their proboscis: chemicals that mimic a marine worm’s mating pheromone.

The study, published on March 12 in the journal Science Advances, identifies two chemicals in the imperial cone snail’s venom that make marine worms go wild. One, called conazolium A, has a similar shape to ovathiol A, a pheromone that entices female worms to emerge from their hiding spots and swim in circles, which is a step toward mating. Another chemical in the venom, genuanine, mimics a molecule called urate, which makes male worms emerge and release sperm.

The researchers measured the chemicals’ effect on worms in the lab, but they suspect that cone snails use the fake pheromones to lure worms into the open and then eat them.

“It’s incredible what these animals can do,” says University of Canterbury biologist Fiona Cross, who wasn’t involved in the study but whose research focuses on spiders that hunt by a similar strategy, to the Atlantic’s Katherine J. Wu. “They’re so in tune with the biology of their prey.”

Most cone snail research thus far has focused on the many species that hunt fish by stabbing them with the harpoon-like hooked tooth at the end of a long proboscis. The tooth often delivers a paralyzing venom that first freezes the fish and then induces paralysis. In 2015, scientists discovered that one species of cone snail sends out a cloud of insulin to paralyze groups of fish all at once.

The diversity of clever chemicals at cone snails’ disposal has led many researchers to scour their tools for potential pain medications. That search has already led to one such drug, a non-narcotic pain-reliever called Prialt. The research team, led by University of Copenhagen medicinal chemist Joshua Torres, were searching for more medical candidates when they noticed the similarities between the imperial cone snail’s venom and the worms’ pheromones, Jonathan Lambert reports for Science News.

The chemicals in the venom aren’t exactly identical to the pheromones, but they’re actually more stable. That might give them the opportunity to waft to wherever the worms are hiding, in tubes and crevices in the sediment, and draw them out into the open where a cone snail can catch them, Celia Henry Arnaud reports for Chemical & Engineering News.

If confirmed with research in the wild, it would mean that the cone snails are “weaponizing the worms’ own pheromone as a sort of lure,” says Torres to Science News. “It’s really wild.”

The researchers began testing this hypothesis by exposing the marine worms to the pheromone-like chemicals while in glass dishes in the lab. The worms responded as they would have to real pheromones—swimming in circles or releasing gobs of sperm. Observations of wild imperial cone snails and marine worms will be necessary to see if the mollusks put this strategy to use.

“Cone snails are full of surprises, and this paper raises an exciting possibility,” says University of Michigan evolutionary biologist Thomas Duda, who wasn’t involved in the study, to Science News. “The next step needs to be figuring out how this actually works in nature.”

The study included 22 imperial cone snails from deep and shallow waters around the Pacific, gathered carefully with tongs, Torres tells the Atlantic. The snails are generally timid, but if handled aggressively, they can attack humans with disastrous results.

Analysis of the chemicals in the deep-water and shallow-water cone snails also revealed that the two creatures may be two different species, but this assertion requires more research to confirm. For instance, the shallow-water snails’ venom apparently lacked conazolium A, the chemical that made the female worms start spinning. The size difference between snails from the two locations was quite noticeable, with the shallow-water snails appearing quite larger.

Whatever future research reveals, the snails have at least one thing in common. “Cone snails have mastered chemistry,” says Torres to the Atlantic. “They are smarter than we are.”