Fish Tools

Using an anvil to smash prey sounds like something Wile E. Coyote would try—unsuccessfully, of course. But some other creatures are a lot more successful at it: fish. More than two dozen species of fish have been seen using “anvils” to smash open their prey. All of them were types of wrasse, a colorful fish found around the world.

Tool use has been observed in birds, mammals, and other animals on land. In marine environments, it’s been seen in octopuses and crabs. And for several decades, the list has included wrasses.

The fish grabs a potential dinner—a crab, urchin, or other morsel with a shell. It then swims to a rock, a coral, or some other hard surface—objects that scientists describe as “anvils.” The fish then smashes the prey against the anvil until the shell cracks open.

A recent study added three species of wrasse to the list of anvil users, and confirmed the use by two other species. All five species were found in the western Atlantic Ocean, from the Caribbean Sea down to the southern coast of Brazil. The smashups were recorded by divers—either on video or in writing—then uploaded to a web site.

On average, the fish had to smash the prey more than half a dozen times, in a bout lasting more than a minute. If one anvil didn’t work, they’d move to another. Of the 16 prey-bashing episodes recorded, only one ended in failure. So perhaps the wrasse could teach Wile E. a thing or two about using an anvil to get the goods.