22 February 2012
A robotic fish has sailed across an aquatic uncanny valley by tricking real fish into following it upstream.
The feat could lead to better understanding of fish behavior and perhaps some means to divert them from environmental disaster scenes.
“Although some previous works have successfully investigated the interactions between live animals and robots or animal-like replicas, none of these studies have considered robots that are designed to simulate animal locomotion,” wrote the authors of a new study about the robot.
Forming schools confers both advantages and disadvantages to fish. The collaborative groups can improve access to mates, make it easier to move through water and confuse predators. On the downside, schools increase competition for food and mates, and provide an excellent way for parasites and disease to spread. Understanding why and how fish school is an open question in science.
To help investigate the dynamics of fish schooling, Marras and Porfiri designed a robot inspired by Notemigonus crysoleucas, a species of Golden shiner. The plastic-covered robofish was twice the size of the real fish but mimicked its back-and-forth tail motion.
When the researchers plopped single Golden shiners into a water tunnel meant to simulate a stream-like current, each fish swam in school-like positions near their robotic counterparts for several minutes (video below). Around a robot that didn’t move, however, the Golden shiners swam randomly for shorter periods of time.
Although some fish kept a wary distance ahead of the robot — they may have perceived it as a threat — most kept pace by trailing in the machine’s watery wake. The behavior matched that of fish in the wild, which group into schools to reduce drag and make swimming more efficient.
It’s unclear why or how the fish accept a robot into their ranks, but the researchers suspect it has to do with the lifelike tail motion and similar body plan.
Outside of animal behavior laboratories, remote-controlled robofish might be used to help mitigate the damage of human-caused ecological disasters.
“If accepted by the animals, robotic fish may act as leaders and drive them away from human-induced ecological disasters that are affecting life in aquatic environments, such as oil spills, and man-made structures, such as dams,” the authors wrote.