Fluid Stigmergy: Investigating the self-organizing principles of animal collectives across scales

Abstract

Collective behavior is a ubiquitous phenomenon observed in a diverse array of species across scales, from single-celled microorganisms to large vertebrates like fish and birds. In aquatic and aerial environments, collective movements are inherently mechanical: as organisms move, they displace the surrounding medium, creating dynamic flow fields that provide opportunities for passive energy recycling and active fluid-mediated communication. We demonstrate how animals across scales assemble in fluid environments of different Reynolds number (Re) regimes. In addition, we highlight how emerging methodologies from artificial intelligence to biomimetic robotics enable new measurements of collective behavior in dynamic fluid environments. Finally, we propose a comparative framework that explores fluid-mediated collective behavior as a critical link between functional morphology and behavioral ecology.