image: This is the robofish model. view more
Credit: Jolyon Faria
To gain insights into group dynamics for the study of collective animal behavior in moving groups, robots have a valuable role to play. Enter "Robofish", a computer-controlled replica stickleback that can be programmed to move around a tank. The brainchild of biologists from the University of Leeds in the UK, Robofish can both recruit and lead fish and shed light on what motivates fish in a shoal to change direction – in this case, the number of neighboring fish is more influential than the absolute distance from the shoal leader. The findings have just been published in Springer's journal Behavioral Ecology and Sociobiology.
Lead author of the study Jolyon Faria and his team introduce a novel tool to study the collective behavior of fish, and in particular, how individuals influence the movement of others in the group. They constructed Robofish and looked at two types of interaction between three-spined sticklebacks and Robofish: recruitment of fish from a refuge and initiation of a new swimming direction to test leadership. They placed Robofish in a tank with live fish collected from the Great Eau river estuary in the UK and observed the fishes' behavior in response to Robofish leaving the refuge, and shortly after, making a 90 degree turn.
Robofish quickly encouraged single fish out of the tank refuge, that would normally hesitate to venture out, and was able to make both single fish and fish in groups of up to ten turn inside the tank in the same direction as itself, demonstrating Robofish's ability to be a leader. The influence of Robofish fell after the first 30 minutes the fish had spent in the new tank.
The researchers then looked at the influence of Robofish on the orientation of fish in a shoal of ten. They found that the interactions between the fish during the change of direction (turn) were influenced by the number of neighbouring fish (topological distance) rather than the fishes' distance from Robofish (metric distance). According to the authors, these findings suggest that modeling individuals in topological, rather than metric, interactions will more closely replicate and predict the behavior of shoaling fish.
Faria and team conclude: "Our method provides an effective means to test the effect of individual attributes such as behavior and morphology on inter-individual responses in shoals, and resultant shoal dynamics. This may provide a better understanding not only of fish behavior but also contribute to a more general understanding of collective animal behavior."
Reference
Faria J et al (2010). A novel method for investigating the collective behavior of fish: introducing "Robofish". Behavioral Ecology and Sociobiology; DOI 10.1007/s00265-010-0988-y
Journal
Behavioral Ecology and Sociobiology