Foraging movements of the sea starAsterias forbesi(Desor) (Echinodermata: Asteroidea) in Narragansett Bay, Rhode Island U.S.A.

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Abstract
The movements of marked sea stars Asterias forbesi in the field were recorded under various conditions of prey density. Sea star movement is random, not directional. Individual sea stars did not show a preferred direction from one day to the next. The population of marked sea stars rarely moved in the same direction at any one time. Negative photoaxis, rather than rheotaxis, best explains these infrequent occurrences of uniform population movement. Sea star movement observed in this study does not comply with some of the predictions of optimal foraging models. These models predict a predator should have directional search paths, and alternate paths dependent on prey density. Existing models which predict an animal's search path apply only to active, highly mobile predators. This study emphasizes the need for a model which incorporates the sensory and learning capabilities of a predator.