Noise-induced schooling of fish

TitleNoise-induced schooling of fish
Publication TypeJournal Article
Year of Publication2020
AuthorsJhawar J, Morris RG, Amith-Kumar U.R, M. Raj D, Rogers T, Rajendran H, Guttal V
Date Published2020/03/02
ISBN Number1745-2481
KeywordsBiological Physics, Biophysics, nonlinear dynamics, Statistical physics, Thermodynamics

We report on the dynamics of collective alignment in groups of the cichlid fish Etroplus suratensis. Focusing on small- to intermediate-sized groups (10 ≲ N ≲ 100), we demonstrate that schooling (highly polarized and coherent motion) is noise induced, arising from the intrinsic stochasticity associated with finite numbers of interacting fish. The fewer the fish, the greater the (multiplicative) noise and therefore the greater the likelihood of alignment. Such rare empirical evidence tightly constrains the possible underlying interactions that govern fish alignment, suggesting that E. suratensis either spontaneously change their direction or copy the direction of another fish, without any local averaging (the otherwise canonical mechanism of collective alignment). Our study therefore highlights the importance of stochasticity in behavioural inference. Furthermore, rather than simply obscuring otherwise deterministic dynamics, noise can be fundamental to the characterization of emergent collective behaviours.

Short TitleNature Physics
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