Abstract
How is light perceived? The answer that might immediately come to mind is, through the eyes. Fly larvae, however, can 'feel' light using specialized neurons embedded under the cuticle encasing their bodies. See Article p.921
Light perception is a highly useful skill. Like other animals, we humans rely on vision to navigate, to locate food and mates, and to avoid predators. But biological applications of light perception go well beyond vision — from basic light-avoidance to circadian rhythms1. What's more, photoreceptive cells are located not only in the eyes, but also in various non-ocular locations, ranging from the skin in molluscs2 to the hypothalamus deep within a bird's brain3. Even overtly eyeless animals, such as the soil-dwelling nematode Caenorhabditis elegans, possess photosensitive neurons that help them to avoid the daylight4.
In this issue, Xiang et al.5 (page 921) extend the analysis of non-ocular photoreception to the fruitfly Drosophila melanogaster. They describe a set of dermal photoreceptors that, surprisingly, had previously escaped notice in this well-studied organism, and uncover a molecular mechanism of phototransduction that has not been previously encountered in the fly.