Regular Article

Rheotaxis performance increases with group size in a coupled phase model with sensory noise

The effects of noise and group size on rheotaxis

¹ Neuroscience and Cognitive Science, Department of Aerospace Engineering, University of Maryland, College Park, Maryland, USA
² Department of Ecology and Evolutionary Biology, Princeton University, Princeton, USA
³ Department of Biological Sciences, Bowling Green State University, Bowling Green, Ohio, USA
⁴ Department of Aerospace Engineering and Institute for Systems Research, University of Maryland, College Park, Maryland, USA

^a e-mail: dpaley@umd.edu

Received: 13 April 2015
Revised: 2 November 2015
Published online: 15 December 2015

Abstract

Many fish exhibit rheotaxis, a behavior in which fish orient themselves relative to flow. Rheotaxis confers many benefits, including energetic cost savings and interception of drifting prey. Despite the fact that most species of fish school during at least some portion of their life, little is known about the importance of rheotactic behavior to schooling fish and, conversely, how the presence of nearby conspecifics affects rheotactic behavior. Understanding how rheotaxis is modified by social factors is thus of ecological importance. Here we present a mathematical model in the form of an all-to-all, coupled-oscillator framework over the non-Euclidean space of fish orientations to model group rheotactic behavior. Individuals in the model measure the orientation of their neighbors and the flow direction relative to their own orientation. These measures are corrupted by sensory noise. We study the effect of sensory noise and group size on internal (i.e., within the school) and external (i.e., with the flow) disagreement in orientation. We find that under noisy environmental conditions, increased group size improves rheotaxis. Results of this study have implications for understanding animal behavior, as well as for potential applications in bio-inspired engineering.