The functional organization of an eye with bifocal lens.

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Almost all animal eyes follow a few and relatively well-understood functional plans. Only rarely is an eye discovered that diverges fundamentally from known types, yet such exceptions frequently lead to exciting new discoveries in visual system function. The principal eyes of the Sunburst Diving Beetle larvae (Thermonectus marmoratus) are among the most bizarre and strangely organized eyes in the animal kingdom, yet the larvae are extremely successful at capturing prey. How does the unorthodox visual system facilitate efficient prey capture? Anatomically, the eyes are characterized by multiple layered retinas, one of which is sensitive to green light whereas a second, deeper retina is sensitive to UV light. It was recently discovered that this visual system operates with truly bifocal lenses, an organization never before demonstrated in an animal; this finding leads to the possibility that each retina receives its own sharp image. Moreover it has become clear that these bifocal lenses use an interesting optical asymmetry that allows the animal to see each of the two images more clearly. This project will use histological and optical techniques to investigate the physical and optical organization of lenses and will use physiological measurements to determine how light excites individual photoreceptors. Throughout the project, several undergraduate and graduate students will be trained, and outreach activities will include science experiments at local schools. A broader impact on the society at large is expected from a better understanding of the design principles of these bifocal lenses, principles that potentially could lead to improved designs of commercial bifocal and multifocal systems and the development of novel materials.