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DeVoe, R. D. (1972). Dual Sensitivities of Cells in Wolf Spider Eyes at Ultraviolet and Visible Wavelengths of Light. JGP, 59(3), 247–269.
Abstract: Intracellular recordings have been made from visual cells in principal and secondary eyes of in vitro wolf spider preparations. The responses of all cells to all wavelengths of light were graded depolarizations; no hyperpolarizations or nerve discharges were seen. Cells in a secondary eye, the anterior lateral eye, had a maximum sensitivity in the visible at 510 nm and a secondary maximum, or shoulder, of sensitivity in the near ultraviolet at 380 nm. Cells in principal eyes, the anterior median eyes, all responded maximally both in the visible at 510 nm and in the ultraviolet at 360-370 nm or less. However, there was no typical ratio of ultraviolet to visible sensitivities; the differences in log sensitivities (log UV/VIS) varied from 3.3 to -0.5. Each principal eye had a population of cells with different ratios. These populations varied with the time of the year, possibly due to changes in light upon the animals. Chromatic adaptations of cells in anterior median (but not anterior lateral) eyes resulted in small, selective changes in spectral sensitivities, and there was some facilitation of responses from cells repeatedly stimulated. It is concluded that cells of secondary eyes contain only a visual pigment absorbing maximally in the visible, while cells of principal eyes probably contain variable amounts of both this pigment and one absorbing in the ultraviolet as well.
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Warrant, E. (2004). Vision in the dimmest habitats on earth. J Comp Physiol A Neuroethol Sens Neural Behav Physiol, 190(10), 765–789.
Abstract: A very large proportion of the world's animal species are active in dim light, either under the cover of night or in the depths of the sea. The worlds they see can be dim and extended, with light reaching the eyes from all directions at once, or they can be composed of bright point sources, like the multitudes of stars seen in a clear night sky or the rare sparks of bioluminescence that are visible in the deep sea. The eye designs of nocturnal and deep-sea animals have evolved in response to these two very different types of habitats, being optimised for maximum sensitivity to extended scenes, or to point sources, or to both. After describing the many visual adaptations that have evolved across the animal kingdom for maximising sensitivity to extended and point-source scenes, I then use case studies from the recent literature to show how these adaptations have endowed nocturnal animals with excellent vision. Nocturnal animals can see colour and negotiate dimly illuminated obstacles during flight. They can also navigate using learned terrestrial landmarks, the constellations of stars or the dim pattern of polarised light formed around the moon. The conclusion from these studies is clear: nocturnal habitats are just as rich in visual details as diurnal habitats are, and nocturnal animals have evolved visual systems capable of exploiting them. The same is certainly true of deep-sea animals, as future research will no doubt reveal.
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