Synergistic mechanisms of dorsal and anal fins in the C-turn maneuvers of zebrafish

This study aims to provide a deeper understanding of the role of fish fins in the C-turn maneuvers of zebrafish. A three-dimensional geometric model that focuses on detailed modeling of the dorsal and anal fins is constructed using experimental data. Utilizing a self-propulsion computational model, we simulate the dynamics of the zebrafish's C-turn at various turning amplitudes, exploring how the fins interact with water to suppress the lateral flow and enhance the propulsion performance. The results indicate that during small-angle C-turn maneuvers, the anal and dorsal fins increase the maximum and minimum velocities during the bending phase by approximately 10% and 7%, respectively, while the maximum velocity during the recoil phase increases by about 5%. As the turning angle increases, the enhancement effect of the fin propulsion performance diminishes. Furthermore, the synergistic effect of the dorsal and anal fins enhances stability, allowing the fish to complete turns at a relatively stable angular velocity and facilitating “accelerated turning.” This study provides new insights into the adaptive significance of fin structures in nature and their influence on dynamic behavior.