Any inventory of the animal world quickly re veals a bewildering assortment of evolved visual systems that allow for the detection and use of information from light. These range from el ementary photoreceptors that only discriminate light from dark, to the considerably more com plex interactions of eye and brain that are re sponsible for visual perception in birds and mammals. This ability of nervous systems to construct internal visual representations of the outside world represents one of the most impor tant milestones in the evolution of animal be havior and cognition. “Seeing” has the great advantage of allowing animals to obtain infor mation concerning the nature and location of objects in their environment without the need for direct or close physical contact, as required by more proximal senses like touch, taste, and smell. Because of this, visual information has become crucial to many animals for locating and identifying food, suitable habitats, preda tors, and conspecifics, as well as functioning to orient animals in their overall surroundings.