Abstract
Stomatopod crustaceans, commonly known as mantis shrimp, have perhaps the most unusual color-vision systems of any animals. The uniqueness is possible because stomatopods have compound eyes. Here, each unit, or ommatidium, acts as an independent visual detector, with its own corneal lens, internal optics, and set of photoreceptors. Ommatidia tuned to different wavelengths can be individually placed in the eye to build unusual color systems. In mantis shrimps, the receptors responsible for color vision are limited to six parallel rows of ommatidia that together form an equatorial belt, called the midband. Various receptors in these ommatidia are tuned to eight narrow-band spectral channels in the visible spectrum plus up to four additional ultraviolet channels. Thus, there is a total of twelve different color receptors for color vision. How these color channels are analyzed in the complex set of optic lobes existing behind the retina is only partly understood. It appears that stomatopods use both opponent and labelled-line color channels. Oddly, these animals appear to have limited ability to discriminate between spectral lights, but they have outstanding color constancy. Color vision, and color processing, in stomatopods is probably unlike that of any other animal group.