Meeting Abstract
The paths animals take while moving through their environments can determine the likelihood of encountering food and other resources, thus models of foraging behavior abound. To collect movement data appropriate for comparison with these models, we used time-lapse photography to track movements of a small, hardy and easy to obtain organism, Aquilonastra sea stars. We recorded the sea stars in a tank over many hours, with and without a food cue. With food present, they covered less distance, as predicted by theory because this strategy would allow them to remain near food. We compared the search performance of the observed sea star movements to Brownian motion and Lévy walks using simulation and found that a model incorporating intermediate correlated random walk behavior drawn from observed Aquilonastra tracks outperformed Lévy and Brownian models when the target was at middling distances from the starting position. In contrast, our intermediate model was outperformed by Brownian walkers at close distances, and by Lévy walkers at far distances. Thus, Aquilonastra may have a movement strategy that allows them to effectively locate resources outside their immediate detection range. Furthermore, while organisms are unlikely to truly follow an idealized random walk such as a Lévy walk in all details, our data suggest that comparing the effectiveness of a given organism’s paths to those from theory can give insight into the organism’s actual movement strategy. Additionally, automated optical tracking of invertebrates proved feasible and Aquilonastra was a revealed to be a tractable tabletop 2D movement study system.
