Physics: Noise drives schools of fish

The schooling of fish may be informed by the intrinsic noise that naturally occurs among a group of interacting individuals, suggests a paper published this week in Nature Physics. These findings may demonstrate the important role of noise in the collective behaviour of animal groups.

Over the past decade, much effort has been made to study the collective motion of animal groups and, by proxy, the interactions between the groups’ individuals. However, much of the research has overlooked the role of the intrinsic noise.

When studying collective groups, researchers usually consider noise as something to be filtered out and disregarded. However, Jitesh Jhawar and colleagues suggest that noise informs the dynamics of schools of fish. Schooling is considered to be highly aligned motion among a group of fish. The authors performed experiments with groups of cichlid fish (Etroplus suratensis) to measure how well aligned group members were with each other and how the alignment fluctuated over time. They found that the fewer the fish in a group, the greater the intrinsic noise and therefore the likelihood of alignment. This implies extremely simple rules of individual behaviour: fish either change their direction spontaneously, or copy the direction of a randomly chosen fish.

The authors conclude that these findings indicate that noise arising from random interactions between individuals might serve as a mechanism for driving particular group behaviours.