A third strategy, “strike and stalk,” might be more macabre still. Many fish, wise to the danger of cone snails, might “gang up and viciously attack” one, Olivera said. So some snails will spend most of their time hiding, emerging only to sting a fish without tethering it. The snipe is so fast that some fish might never notice they’ve been hit. But within minutes, the toxins of these particular venoms will have worked their insidious magic: The fish will crumple, sluggish and quivering, allowing the snail to approach from behind and gulp it down gleefully.
Most of what’s known about these gastropods has been learned from studying fish hunters, arguably the flashiest ones of the bunch. But most cone snails prefer to munch on marine worms, and seem to engage an entirely different set of toxin-based strategies to do so. Torres, Schmidt, Olivera, Safavi-Hemami, and their colleagues recently discovered that one such tactic might involve tricking worms into thinking they’re about to get laid—a promise that rouses the wriggly creatures from their hidey-holes, only to end their life.
Torres’s team found that worm-hunting cone snails have evolved to produce molecules that resemble the pheromones of their prey. One chemical, conazolium A, looks like a pheromone that makes female worms swim in tight, tail-chasing circles before spewing their eggs; another is reminiscent of uric acid, which prompts males to eject gobs of sperm. Spritzed onto marine worms in the lab, the snail-made pheromones whipped most of the specimens into a sexual frenzy.
The pheromones “are a lure,” says Mandë Holford, a cone-snail-venom chemist at Hunter College. “I don’t think the worms even see it coming.” These cone snails are chemical saboteurs; they have weaponized another species’ appetite for sex. Because many marine worms die after reproducing, some of the ones consumed by cone snails likely die as duped virgins, their biological imperative unfulfilled.
Like the insulin-producers, these worm-hunting cone snails simulate chemicals naturally found in their prey. But while the insulin cohort seems to tame its targets, the pheromone-makers rile theirs up; both behaviors seem to bring hunter and huntee into close contact. “It’s incredible what these animals can do,” says Fiona Cross, a biologist at the University of Canterbury who studies spiders that also imitate other animals’ sexual attractants. “They’re so in tune with the biology of their prey.”
Torres and his colleagues still aren’t sure how the snails use these pheromones in natural contexts. They might inject them, like paralytics, or exude them to bathe their unsuspecting prey in eau de worm. Zhenjian Lin, a biochemist at the University of Utah, thinks the worm hunters might use their venom in multiple ways, first to attract, then to immobilize.