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Publisher Summary The most important organ for photoreception in fishes is the eye. The eye has special significance because it is a visual organ, capable of image-formation. This chapter discusses several aspects of photoreception in fishes, especially marine fishes. It deals with the photobehavior and the functioning of the eye in marine environments. Rhodopsins, based on vitamin A 1 aldehyde, are characteristic of marine fishes. They have a great range of absorption maxima, ranging from maxima around 480 mμ (visual golds or chrysopsins of deep-sea species) to purple rhodopsins with maxima around 510 mμ in fishes of turbid coastal waters. The absorption characteristics of these various scotopic visual pigments are related to the quality of light in the environment–residual blue daylight or luminescence in clear oceanic waters, filtered blue-green or green light in inshore waters. Recent ethological and ecological studies concerned with photio stimuli have dealt with color changes, schooling, migratory movements of katadromous salmon and trout, diurnal vertical migrations, responses to intermittent light, colored lights and strong steady lights, and the operation of sun-compass reactions in horizontal migrations. |
