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Stomatopod eyes: The most complex visual organs on the planet! Why?

Roy L. Caldwell, Ph.D.
University of California, Berkeley

Wednesday, April 18, 2001
3:00 p.m.–Pacific Forum

The Stomatopoda are a small but diverse group of marine predators that have evolved powerful raptorial appendages. In species that I call smashers, the appendage is specialized for breaking apart armored prey. The ability to land crushing blows also provides them with a potent weapon that can be employed for defense and in agonistic encounters. Evolution does not occur in a vacuum and with the rise of the raptorial appendages came changes to almost every aspect of stomatopod biology. Perhaps the most dramatic of these was the development of sophisticated sensory systems to direct the use of these lethal weapons and to provide information about similarly armed opponents.

The eyes of gonodactyloid and lysiosquilloid stomatopods are arguably the most complex visual organs in the animal kingdom. They judge distance based on the shape of the eye and/or orientation of the individual ommatidia. A single species can have up to 16 different visual pigments with peak spectral sensitivities extending from the ultraviolet to the red. These pigments are combined with up to four visual filters that further tune the visual receptors. Furthermore, recent work has shown that the color vision system is developmentally plastic altering spectral sensitivity in response to ambient light conditions. Finally, stomatopods have the ability to distinguish among targets reflecting light of different e-vectors and are among the only animals known to uses displays that involve complex polarized signals.

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