9411834 Kier The brittle star sensory system is paradoxical in that it combines high reactivity, quick movements, and occasional predatory behavior with a total lack of a discrete sense organ. In addition brittle stars can discriminate between polarized and unpolarized light and this perception could be based on differential light transmission through a polarizing skeleton. This study will provide crucial information on (1) the nature and capabilities of diffuse sensory systems and (2) a possibly novel mechanism of polarization sensitivity. Experiments will determine whether and how the novel optical property of the endoskeleton of the brittle star is used by the animal. This proposal outlines the first opportunity to study the function of a biological polarizing filter. ***
