One of the sea's slowest creatures may also be its fastest hunter. A new study reveals that the fish-hunting cone snail immobilizes passing fish by firing a harpoonlike tooth at them. The entire process--from detecting the prey to stunning it--takes less than 300 milliseconds, making it one of the quickest captures known.
Scientists have long been interested in the deadly toxins cone snails use to paralyze their prey, exploiting them for neuroscience research and drug development. But little was known about how the snails get this venom into their victims and how they stop fish dead in their tracks.
To address these questions, a team of researchers from Stanford University's Hopkins Marine Station in Pacific Grove, California, constructed a setup that would give them a view to a kill. They attached a fish and an underwater high-speed video camera to one end of a small acrylic trough. When a Conus catus snail at the opposite end of the trough sensed the fish, it guided its translucent proboscis down the trough's furrow until it touched the fish. Then, in less than a third of a second, the camera recorded the proboscis constricting, launching a hollow harpoon-shaped tooth into the fish, and injecting venom through the tooth into the fish. The base of the tooth is gripped by the proboscis during the entire event--so it never actually leaves the snail's body--and is used as a hook to draw the fish in, the team reports in the October issue of The Biological Bulletin.The incredible speed of this ballistic method of prey capture explains how these snails can capture such fast prey, says lead researcher Joseph Schulz, now at Occidental College in Los Angeles. He notes that it is still unclear how the constriction of the proboscis readies the tooth for launch, but he believes it may somehow build up pressure at the base of the tooth."This is a really good piece of work," says Jon-Paul Bingham, a biochemist and cone snail farmer at Clarkson University in Potsdam, New York. The trick used by the fish-hunting cone snail is "extremely unique" in the animal kingdom, he says, and may have evolved to allow these creatures to expand their diet.