Hail robofish…..courtesy University of Leeds

Making lifelike animal decoys is a very old human activity, especially for hunters. Some of the results are surprisingly accurate in appearance – but they don’t move. On the other hand robotic devices move, but making them move in a lifelike way – that’s difficult. Researchers at the University of Leeds (UK) have succeeded in creating the first robotic fish lifelike enough to entice other fish of its species to follow it. Published in Behavioural Ecology and Sociobiology as A novel method for investigating the collective behaviour of fish: introducing ‘Robofish’” the artificial stickleback was tested one-on-one and in a group of other sticklebacks. The researchers programmed it to swim slightly faster than normal for the species, making it seem like a more aggressive or risk taking fish. This behavior seemed to overcome any deficiencies in the decoy appearance, smell or behavior so that the other fish consistently followed its lead.

The computer controlled replica – dubbed Robofish by its creators John Dyer, Dr Dean Waters and Natalie Holt – is a plaster cast model of a three-spined stickleback with an acetate fin, painted to mimic the coloration and markings of a real fish. The scientists needed to prove that Robofish was accepted into the group sufficiently for the fish to respond to the robot like a normal shoal member.

“Although Robofish looked like a stickleback to us, we weren’t sure whether the other fish would see it in the same light,” explained Jolyon. “We also thought there might be a problem with the smell, as fish use chemical cues in the water to identify other shoal members. In the end, Robofish was accepted straight away – though we did trial various models until we found one that worked the best.”

[Source: University of Leeds]

The significance of Robofish and the many other types of lifelike robotics under development around the world is both to demonstrate the advances in robotics, especially the sophistication of motor control, and also the ability of robotics like this to provide a whole new way of experimenting with live subjects. The robotic decoy introduces the ability to guide, provoke, and manipulate the behavior of groups – and to observe the results. In this case, for example, with one experiment the researchers were able to show that the shoal of fish would follow the lead of Robofish turning not, as expected, whether they were close to it or not but whether they held second, third or other position relative to it.

The utility of such realistic decoys will not long escape the attention of the world’s greatest predator (humans as hunters, of course).