Meeting Abstract
The navigation strategies animals use to find odor sources depend on the odor stimuli, the fluid flow properties, and the locomotory capabilities of the animal. In high reynold’s number environments, animals typically use odor-gated rheotaxis (OGR) to find the source of turbulent odor plumes. This strategy succeeds because although turbulence creates an intermittent chemical cue, the animal follows the (continuous) flow cue that is transporting the chemical. However, in nature, animals may lose all contact with an odor plume as variations in bulk flow direction cause the plume to be rotated away before the animal reaches the source. Our goal was to use a mathematical model to explore the range of circumstances where different strategies that augment OGR might be beneficial for finding an odour source in such variable flow. The model links a stochastic variable-direction odor plume with a turbulence-based intermittent chemical signal and four different movement strategies, including: OGR alone (as a control), OGR followed by further rheotaxis in the absence of odor, OGR followed by a random walk, and OGR followed by movement actively guided by the last flow heading detected with odor present. We found that any of the three augmented strategies could improve on strict odor-gated rheotaxis. Moreover, the best strategy depended on the distance from the odor source, rate of movement of the animal, and the magnitude of flow variation. Our results suggest that animals that rely on odor cues to navigate in turbulent environments may be subject to selective forces affecting both immediate responses to odor cues as well as more delayed responses that could more fully exploit the information that can be derived from odor plumes.
