Random patterns in fish schooling enhance alertness: a hydrodynamic perspective

TL;DR

This study reveals that fish schooling with random patterns enhances hydrodynamic information transfer, potentially improving survival, and challenges the notion that ordered formations are always optimal for collective animal behavior.

Contribution

It demonstrates that disordered, chaotic fish schooling patterns can optimize hydrodynamic information transfer, offering new insights into collective behavior from a hydrodynamic perspective.

Findings

Random schooling patterns increase hydrodynamic information transfer.

Disordered behavior may be crucial for survival in fish schools.

Hydrodynamic forces support the benefit of chaotic collective patterns.

Abstract

One of the most highly debated questions in the field of animal swarming and social behaviour, is the collective random patterns and chaotic behaviour formed by some animal species, in particular if there is a danger. Is such a behaviour beneficial or unfavourable for survival? Here we report on one of the most remarkable forms of animal swarming and social behaviour - fish schooling - from a hydrodynamic point of view. We found that some fish species do not have preferred orientation and they swarm in a random pattern mode, despite the excess of energy consumed. Our analyses, which includes calculations of the hydrodynamic forces between slender bodies, show that such a behaviour enhances the transfer of hydrodynamic information, and thus enhances the survivability of the school. These findings support the general hypothesis that a disordered and non-trivial collective behaviour of individuals within a nonlinear dynamical system is essential for optimising transfer of information - an optimisation that might be crucial for survival.