Covering Ground: A Look at Movement Patterns and Random Walk Behavior in Aquilonastra Sea Stars

Authors

Amanda C. Lohmann, University of North Carolina at Chapel Hill
Dennis Evangelista, United States Naval Academy
Lindsay D. Waldrop, Chapman UniversityFollow
Christopher L. Mah, National Museum of Natural History, Smithsonian Institution
Tyson L. Hedrick, University of North Carolina at Chapel HillFollow

Document Type

Article

Publication Date

10-2016

Abstract

The paths animals take while moving through their environments affect their 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 anomala 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; this strategy would allow them to remain near food. We then compared the paths of the sea stars to three common models of animal movement: Brownian motion, Lévy walks, and correlated random walks; we found that the sea stars’ movements most closely resembled a correlated random walk. Additionally, we compared the search performance of models of Brownian motion, a Lévy walk, and a correlated random walk to that of a model based on the sea stars’ movements. We found that the behavior of the modeled sea star walk was similar to that of the modeled correlated random walk and the Brownian motion model, but that the sea star walk was slightly more likely than the other walks to find targets at intermediate distances. While organisms are unlikely to follow an idealized random walk in all details, our data suggest that comparing the effectiveness of an organism’s paths to those from theory can give insight into the organism’s actual movement strategy. Finally, automated optical tracking of invertebrates proved feasible, and A. anomala was revealed to be a tractable, 2D-movement study system.

Comments

This article was originally published in Biological Bulletin, volume 231, issue 2, in 2016. https://doi.org/10.1086/690093

Recommended Citation

A.C. Lohmann, D.E. Evangelista, L.D. Waldrop, C. Mah, T.L. Hedrick. 2016. Covering ground: a look at movement patterns and random walk behavior in Aquilonastra sea stars. Biological Bulletin 231(2): 130-141. https://doi.org/10.1086/690093

Copyright

Marine Biological Laboratory