Self-Organization in Massive Fish Schools

Abstract: The remarkable cohesion and coordination observed in animal groups is thought to arise from scale-free correlations, where changes in the behavior of one animal influence others in the group, regardless of the distance between them. In this talk, I explore scale-free correlation and information propagation in mathematical models of massive schools of fish of the order of 10,000 individuals. I show that (1) as the school size increases, flow interactions destabilize global polarization, creating locally polarized clusters that dynamically self-organize, split and reassemble; (2) while correlations in cohesive and polarized clusters are scale free, splitting events are preceded by a decrease in correlation length; (3) information propagates linearly in time within cohesive groups, thanks to the non-reciprocal nature of interactions between individuals; and (4) the speed of information propagation within cohesive groups is robust to group size but varies with self-organization: merging of separate clusters increases the speed of information transfer within each cluster, while splitting and fragmentation decrease it. I conclude by commenting on the implications of these findings to size regulation and behavioral adaptations in living animal groups.

Eva Adnan Kanso - Bio

Eva Kanso is a professor and the Z.A. Kaprielian Fellow in Aerospace and Mechanical Engineering at USC, with a courtesy appointment in Physics and Astronomy. She is the recipient of the 2024-2025 W.R. Kenan, Jr. Visiting Professorship for Distinguished Teaching in Mechanical and Aerospace Engineering at Princeton University. Kanso received doctorate and masters degrees in Mechanical Engineering and Applied Mathematics from the University of California at Berkeley, followed by a post-doctoral position at Caltech. Kanso studies fundamental problems in the biophysics of cellular and subcellular processes and the physics of animal behavior, both at the individual and collective levels. A central theme in her work is the role of biomechanics and mechanical environment in shaping and driving biological functions.