Consider his idea for biologically inspired robots that might influence animal behavior in nature. "If we borrow design from nature to build our robots, why not use the robots to assist nature?" says Porfiri, who is an assistant professor at the Polytechnic Institute of New York University. "Can we close the circle?" Maybe a robot fish could guide real fish away from power turbines or oil spills. Drawing on research that suggests that fish school by following the wake of other fish, Porfiri designed his robot to generate fishlike turbulence. An electric current from a battery makes a polymer in the tail expand and contract like muscles, producing an eerily natural-looking and silent movement. This spring, he put a biomimetic robot together with actual lab fish, which followed it about 25 percent of the time.