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Video: I, Fishbot

Credit: © Maurizio Porfiri

Call it the swimming equivalent of hypermiling. A new study finds that fish will follow a robotic leader—but only if it makes their own journey easier. Hoping to better understand the structure of fish schools, researchers created a robotic fish—a big plastic body attached to a motorized tail that can move back and forth—and dunked it into a water tunnel alongside golden shiners (Notemigonus crysoleucas), who regularly swim together in large groups. At first, when the robot's tail was motionless, the fish showed little interest in their plastic companion and swam where they wished. But as soon as the robot's tail began to beat back and forth, the fish fell in line, swimming in the wake formed by the flapping tail. Once in formation, the fish also slowed their own tailbeats a little, which suggests the robot leader's swimming eased the drag forces on the fish and made their own swimming more efficient. The results, published online today in Journal of the Royal Society Interface, may help scientists build a better robotic leader of fish, a device that could one day guide fish away from ecological disasters or other threats. 

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