We typically think of eyes as having one or more lenses for focusing incoming light onto a surface such as our retina. However, light can also be focused using arrays of mirrors, as is commonly done in telescopes. A biological example of this is the scallop, which can have up to 200 reflecting eyes that focus light onto two retinas. Palmer et al. find that spatial vision in the scallop is achieved through precise control of the size, shape, and packing density of the tiles of guanine that together make up an image-forming mirror at the back of each of the eyes. More.
The authors dare to use the term “fine-tuned,” with all its career-limiting damage?
The pecten scallop uses mirrors instead of lenses in its eyes.
Abstract: Scallops possess a visual system comprising up to 200 eyes, each containing a concave mirror rather than a lens to focus light. The hierarchical organization of the multilayered mirror is controlled for image formation, from the component guanine crystals at the nanoscale to the complex three-dimensional morphology at the millimeter level. The layered structure of the mirror is tuned to reflect the wavelengths of light penetrating the scallop’s habitat and is tiled with a mosaic of square guanine crystals, which reduces optical aberrations. The mirror forms images on a double-layered retina used for separately imaging the peripheral and central fields of view. The tiled, off-axis mirror of the scallop eye bears a striking resemblance to the segmented mirrors of reflecting telescopes. (paywall) – The image-forming mirror in the eye of the scallop Benjamin A. Palmer, Gavin J. Taylor, Vlad Brumfeld, Dvir Gur, Michal Shemesh, Nadav Elad, Aya Osherov, Dan Oron, Steve Weiner, Lia Addadi Science 01 Dec 2017: Vol. 358, Issue 6367, pp. 1172-1175 | DOI: 10.1126/science.aam9506
A friend offers some extracts:
In some rare visual systems in nature, mirrors are used instead of lenses to produce images (1). A remarkable example of such an eye is found in the Pecten scallop, which possesses up to 200 minute eyes lining the mantle tissue.
Perhaps the most complex optical function of guanine crystals in nature is in image formation. This function demands an extremely high degree of ultrastructural organization because light must not only be reflected but also focused. The hierarchal organization of the scallop mirror is finely tuned for image formation, from the component guanine crystals at the nanoscale to the overall shape of the mirror at the millimeter level (20). The scallop controls the crystal morphology and spacing to produce a tiled multilayer mirror with minimal optical diffraction aberrations, which reflects wavelengths of light that penetrate its habitat and are absorbed by its retinas. The mirror forms functional images on both retinas, which appear to be specialized for different functions.
The crystal morphology, multilayer structure, and 3D shape of the scallop’s eye mirror are finely controlled to produce functional images on its two retinas. Understanding the strategies that organisms use to control crystal morphology and arrangement for complex optical functions paves the way for the construction of novel bio-inspired optical devices (39, 40). In particular, the resemblance of the scallop’s tiled, off-axis mirror to the segmented mirrors of reflecting telescopes provides inspiration for the development of compact, wide-field imaging devices derived from this unusual form of biological optics.
And it all somehow just happened, with no underlying design…
Thought: The way things are going, the war on reason and common sense required to protect Darwinian naturalism will run into problems with the English language, and any other language that is needed to convey meaning. Could researchers buy the right to use conventional meaningful terms now and then without Darwin’s Dobermans let loose on them? Maybe they could apologize in advance and pay a fee… with a special fine levied if the paper is cited anywhere?
See also: Researchers: Earth’s first trees were also “most complex”
Darwinism vs science: Even flu bugs are complex
What becomes of science when the evidence does not matter?