Browsing by Subject "visual pigments"
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Item Photoreception and vision in the ultraviolet(The Company of Biologists Ltd, 2016) Cronin, Thomas W.; Bok, Michael J.Ultraviolet (UV) light occupies the spectral range of wavelengths slightly shorter than those visible to humans. Because of its shorter wavelength, it is more energetic (and potentially more photodamaging) than ‘visible light’, and it is scattered more efficiently in air and water. Until 1990, only a few animals were recognized as being sensitive to UV light, but we now know that a great diversity, possibly even the majority, of animal species can visually detect and respond to it. Here, we discuss the history of research on biological UV photosensitivity and review current major research trends in this field. Some animals use their UV photoreceptors to control simple, innate behaviors, but most incorporate their UV receptors into their general sense of vision. They not only detect UV light but recognize it as a separate color in light fields, on natural objects or living organisms, or in signals displayed by conspecifics. UV visual pigments are based on opsins, the same family of proteins that are used to detect light in conventional photoreceptors. Despite some interesting exceptions, most animal species have a single photoreceptor class devoted to the UV. The roles of UV in vision are manifold, from guiding navigation and orientation behavior, to detecting food and potential predators, to supporting high-level tasks such as mate assessment and intraspecific communication. Our current understanding of UV vision is restricted almost entirely to two phyla: arthropods and chordates (specifically, vertebrates), so there is much comparative work to be done.Item A short-wavelength photoreceptor class in a deep-sea shrimp(The Royal Society, 1996-07-22) Cronin, Thomas W.; Frank, Tamara M.In the world of midwater, mesopelagic animals, downwelling sunlight is filtered by the overlying water to a limited waveband centered near 475 nm. Consequently, the visual pigments of most of these species absorb maximally between 450 and 500 nm. The only exceptions occur in some fishes, which have additional visual pigments absorbing at long wavelengths (550-580 nm) matched to their red bioluminescence. We now find that the mesopelagic decapod shrimp Systellaspis debilis has two visual pigments. One of these absorbs maximally in the expected range (λmax = 498 nm), but the other is maximally sensitive at very short wavelengths, approaching the near-ultraviolet (λmax = 410 nm). The discovery of a visual receptor class absorbing at such short wavelengths in a mesopelagic animal suggests that visual systems in the deep sea may be far more diverse, and potentially more complex, than previously suspected.