Polarized schooling emerges in tetra species with cohesive social networks

Fish schooling depends on social interactions between animals. Studies on schooling overwhelmingly focus on a single species, which challenges our ability to resolve what features of this collective behavior are universal and how it has diversified over the course of evolution. Here, we studied interspecific variation in schooling behavior among five species of Neotropical tetras to examine how social networks relate to schooling kinematics among species. We quantified differences in speed, polarization, spacing, mutual information, and network properties within, and between, species. Our results demonstrate substantial interspecific variation in schooling behavior, with polarized species exhibiting higher speeds and more cohesive social networks. In contrast, shoaling species showed greater variability in their spatial arrangement and a less cohesive social structure. This comparison demonstrates how closely-related species are capable of exhibiting distinct forms of schooling that reflect divergent traits in sensing, motivation, and locomotor control.