I Like You When You Beat Your Tail Like That

All it takes is proper tail technique to turn a giant robot fish into a pickup artist. Scientists from the Polytechnic Institute of New York University constructed a fishy-looking robot with an enlarged abdomen (a shape that's attractive to both male and female zebrafish), and a flexible caudal fin, or tail, that was controlled electronically. They painted it with blue and silver stripes resembling those of a zebrafish, and gave it a yellow face and a large, prominent eye. Then they anchored their robot—which at 15 centimeters long and 4.8 centimeters high was five times larger than an actual zebrafish—inside a glass aquarium. Real zebrafish were then placed, one at a time, inside the aquarium and separated from the robot by an acrylic panel. Perhaps because zebrafish are a naturally gregarious species, they were attracted to the robot—but, the team found, that attraction depended on how the robot beat its tail. The zebrafish especially preferred the robot when it observed and adapted to their motion, beating its tail faster as they approached, and slower as they swam away—a kind of behavior that's known to be attractive in other fish species. The scientists have yet to test whether the zebrafish would choose the responsive robot over their own kind; in previous experiments, given a choice between hanging out with a robot with a steadily beating tail or with their live pals, the zebrafish always preferred the latter. But a sexy robot that modulates its reactions? Stay tuned. 

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