Cronin 9724028 Color is intimately linked to vision throughout the animal kingdom. Color vision can play key roles in recognition of mates or competitors, and in determining effectiveness of camouflage for predators and prey. Visual systems using color have all evolved in the context of the properties of the light in natural scenes; these spectral properties define the potential limits of biologically useful arrays of color receptors in the eyes of animals. Marine animals sometimes lack color vision, but in the most complex forms, some crustaceans have as many as a dozen spectral receptor classes, far more than in any known terrestrial animals. This project analyzes the spectral and spatial properties of natural underwater scenes where these complex crustaceans live, and the signaling systems that these animals use in color-based communication within and between species. The results will help answer how the integrated information from their many spectral types of receptors enables them to exploit color vision in the sea. This study will provide a valuable case of an aquatic invertebrate to compare to terrestrial color vision and its evolution in insects, birds and primates. It is likely to have an impact beyond sensory science, on the fields of marine biology, evolution and ecology, and on the design of remote sensing devices.