Fishlike Rheotaxis

TL;DR

This paper presents a theoretical model of fish rheotaxis using a fishlike body with lateral pressure sensors, demonstrating how sensory input influences orientation and flow alignment, with implications for understanding fish behavior.

Contribution

The study introduces a novel theoretical model linking sensor placement and hydrodynamic information to fish-like flow alignment behavior.

Findings

Optimal sensor locations match hydrodynamic information distribution.

The model predicts fishlike alignment into oncoming flow.

Sensor-based responses replicate observed rheotactic behavior.

Abstract

Fish rheotaxis, or alignment into flow currents, results from intertwined sensory, neural and actuation mechanisms, all coupled with hydrodynamics to produce a behavior that is critical for upstream migration and position holding in oncoming flows. Among several sensory modalities, the lateral line sensory system is thought to play a major role in the fish ability to sense minute water motions in their vicinity and, thus, in their rheotactic behavior. Here, we propose a theoretical model consisting of a fishlike body equipped with lateral pressure sensors in oncoming uniform flows. We compute the optimal sensor locations that maximize the sensory output. Our results confirm recent experimental findings that correlate the layout of the lateral line sensors with the distribution of hydrodynamic information at the fish surface. We then examine the behavioral response of the fishlike model as a function of its orientation and swimming speed relative to the background flow. Our working hypothesis is that fish respond to sensory information by adjusting their orientation according to the perceived difference in pressure. We find that, as in fish rheotaxis, the fishlike body responds by aligning into the oncoming flow. These findings may have significant implications on understanding the interplay between the sensory output and fish behavior.