Bug With Bifocals Baffles Biologists
ScienceDaily (Aug. 24, 2010) — University of Cincinnati researchers are reporting on the discovery of a bug with bifocals -- such an amazing finding that it initially had the researchers questioning whether they could believe their own eyes.
University of Cincinnati researchers are reporting on the discovery of a bug with bifocals -- such an amazing finding that it initially had the researchers questioning whether they could believe their own eyes. (Credit: Elke Buschbeck)
"To the best of our knowledge, this is the first demonstration of truly bifocal lenses in the extant animal kingdom," the researchers state in the Aug. 24 cover feature of the life-science journal Current Biology.
The new article is an exploration of two eyes of the larvae of the sunburst diving beetle (Thermonectus marmoratus). The two eyes have the bifocal lens, which the researchers have found in four of the larvae's 12 eyes, says researcher Elke K. Buschbeck, a UC associate professor of biology.
The article explains that using two retinas and two distinct focal planes that are substantially separated, the larvae can more efficiently use these bifocals, compared with the glasses that humans wear, to switch their vision from up-close to distance -- the better to see and catch their prey, with their favorite food being mosquito larvae.
"In addition, we think that within the principle eyes, separate images of the same object could be focused on each of the two retinas, allowing each eye to function as 'two eyes in one,'" the researchers reveal in the article. The tubular-shaped eyes with the bifocals allow them to effiently focus onto their two retinas, says Annette Stowasser, a UC biology doctoral student and first author on the paper.
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Read more here/Leia mais aqui: Science Daily
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Current Biology, Volume 20, Issue 16, 1482-1486, 05 August 2010
Copyright © 2010 Elsevier Ltd All rights reserved.
10.1016/j.cub.2010.07.012
Authors
Annette Stowasser,Alexandra Rapaport,John E. Layne,Randy C. Morgan,Elke K. BuschbeckSee Affiliations
Highlights
This is the first demonstration of truly bifocal biological lenses
Each of the two main retinas of eye 2 could have its own focused image
The bifocal lens separates the images dorsoventrally in addition to rostrocaudally.
Summary
Almost all animal eyes follow a few, relatively well-understood functional plans. Only rarely do researchers discover an eye that diverges fundamentally from known types. The principal eye E2 of sunburst diving beetle (Thermonectus marmoratus) larvae clearly falls into the rarer category. On the basis of two different tests, we here report that it has truly bifocal lenses, something that has been previously suggested only for certain trilobites [1]. Our evidence comes from (1) the relative contrast in images of a square wave grating and (2) the refraction of a narrow laser beam projected through the lens. T. marmoratus larvae have two retinas at different depths behind the lens, and these are situated so that each can receive its own focused image. This is consistent with a novel eye organization that possibly comprises “two eyes in one.” Moreover, we find that in contrast to most commercial bifocal lenses, the lens of E2 exhibits asymmetry, which results in separation of the images both dorsoventrally and rostrocaudally within the layered retina. Visual contrast might thus be improved over conventional bifocal lenses because the unfocused version of one image is shifted away from the focused version of the other, an organization which could potentially be exploited in optical engineering.
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