This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: For centuries, scientists have been fascinated by the remarkable coordinated movements of flocking birds, swarming insects and schooling fish. Researchers have studied these natural phenomena to understand the rules of interactions between individuals that can produce complex group-level behavior.
A collaboration of physicists and neurobiologists at the University of California San Diego has been studying schools of micro glassfish (Danionella cerebrum) to understand how the interactive mental processes of individual fish produce group-level decisions. Their new paper, published in Physical Review Letters, explores these questions and provides a new understanding of how individual fish use their perception of their neighbors' movements to copy those actions, leading to schooling behavior in groups. The research was led by Palka Puri, a recent graduate of UC San Diego's physics Ph.D. program, with associate professor Johnatan Aljadeff and assistant professor Matthew Lovett-Barron, both faculty members in UC San Diego's School of Biological Sciences.
Puri's work provides a detailed, turn-by-turn account of the schooling behavior of micro glassfish across a range of developmental stages. Based on the computational model developed and investigated in the paper, scientists can now interpret the actions of individual fish and predict the dynamics of schools forming and breaking apart. The findings also open a door to understanding how collective movement—a complex social behavior—emerges from sensory and motor processing in the brain of each fish.
The computational model described in this new paper overcomes prior limitations in the study of animal collectives. While physicists have long investigated collective behavior with models of active matter, it has been challenging to connect these models to the macroscopic movement patterns of animal groups in nature. By examining the movements of fish across group sizes, UC San Diego researchers discovered that individual fish "copy" the movement direction of a randomly chosen nearby neighbor.
This model can explain how schooling emerges during development, as the authors have previously shown. This pairwise interaction leads to highly dynamic behavior in groups, which is fundamentally different from predictions of a classical model, in which fish align with the average direction of their neighbors. The authors then went further, testing whether their models could predict the behavior of real glassfish by studying their interactions with "virtual fish" swimming in a virtual reality environment.
When the authors programmed virtual fish to change directions, the real glassfish behaved according to the predictions of the pairwise copying model. The authors also identified specific moments when fish implement the interactions defined by the model. The end of one fish's turn opens a "window of opportunity" for its neighbors to align with them.
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