Collective Motion, Decision Making and Predator-Prey Interactions in Schooling Fish

A fundamental problem in a wide range of biological disciplines is understanding how functional complexity at a macroscopic scale (such as the functioning of a biological tissue) results from the actions and interactions among the individual components (such as the cells forming the tissue). Animal groups such as bird flocks, fish schools and insect swarms frequently exhibit complex and coordinated collective behaviors and present unrivalled opportunities to link the behavior of individuals with the functioning and efficiency of dynamic group-level properties.

Using an integrated experimental and theoretical approach involving schooling fish I will address both how, and why, animals coordinate behavior. In some schools decision-making by individuals is so integrated that it has been associated with the concept of a “collective mind”. Since each organism has relatively local sensing ability, coordinated fish schools have evolved collective strategies that allow individuals to access higher-order computational abilities at the group level. I investigate the coupling between spatial and information dynamics in schools and reveal the critical role uninformed individuals (those who have no information about the feature upon which a collective decision is being made) play in establishing democratic consensus.

Understanding the information-processing dynamics in groups offers new insight into the evolution of collective behavior. To better understand how and why grouping has evolved, we perform experiments in which real predators (Bluegill sunfish) are used to exert selection pressure on virtual prey populations, allowing us to explore both the within-group and between-group selection pressures that influence the evolution of functional collective behaviour. I will also discuss the results of a study in which predator-prey interactions are observed in situ using multi-beam sonar to reveal the group hunting capabilities of fish and the coordinated response of prey to such threats. Our results provide insights into both the proximate and ultimate factors that underlie evolved collective behavior.