Entirely at random, or so the theory runs…
While study has long been conducted on vertebrates with sight-sensory systems involving a lens, retina and nervous system, new research reported by the University of Cincinnati and supported by the National Science Foundation is the first to examine how the complex eye system of an invertebrate – the Sunburst Diving Beetle – coordinates the development of its components. Despite the complexity of their eyes, including a bifocal lens, extremely rapid eye growth of the Sunburst Diving Beetle occurs during the transitions between larval stages. In addition, they temporarily go blind as the eye is quickly redeveloped. The findings by Shannon Werner, a recent University of Cincinnati master’s degree graduate in the biological sciences, and Elke Buschbeck, a UC professor of biological sciences, is published in the November issue of Comparative Physiology A.
“We were intrigued that all major changes in eye tube length already had taken place at our first sampling point, which was taken within 60 minutes of molting,” report the researchers. “This rapid eye expansion suggests a certain level of pre-determined eye growth, but specific adjustments also could be made at the level of the lens, which takes longer to reform. The lenses transformed more slowly during this period, affecting sight, but were back to being able to produce sharp, bifocal images within eight hours.” More.
If you doubt the “at random” thing, see also: Natural genetic engineering? Natural popcorn? Or something more important? While not ID, self-organization takes the issues as seriously as they deserve, in terms of trying to find a plausible origin for information.
See also: Data Basic
Here’s the abstract:
However complex a visual system is, the size (and growth rate) of all its components—lens, retina and nervous system—must be precisely tuned to each other for the system to be functional. As organisms grow, their eyes must be able to achieve and maintain emmetropia, a state in which photoreceptors receive sharp images of objects that are at infinity. While there has been ample research into how vertebrates coordinate eyes growth, this has never been addressed in arthropods with camera eyes, which tend to grow dramatically and typically in a step-wise manner with each molt (ecdysis). Here, we used histological and optical methods to measure how the larval eyes of Sunburst Diving Beetles (Thermonectus marmoratus, Coleoptera, Dytiscidae) grow, and how well optical and morphological parameters match, during the dramatic growth that occurs between two consecutive larval stages. We find that the eye tubes of the principal eyes of T. marmoratus grow substantially around molt, with the vitreous-like crystalline cone contributing the most to the overall growth. Lenses also reform relatively quickly, undergoing a period of dysfunction and then regaining the ability to project sharp images onto the retina around 8 h post-molt. (paywall) – Shannon Werner, Elke K. Buschbeck. Rapid and step-wise eye growth in molting diving beetle larvae. Journal of Comparative Physiology A, 2015; 201 (11): 1091 DOI: 10.1007/s00359-015-1040-5
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