If you’ve ever been to a fancy restaurant and eaten a scallop, you might think they are little more than a rubbery slug with a nice shell. But don’t be fooled by their looks, these ancient creatures have some incredible biological gadgetry beneath that shell.
A team of Israeli and Swedish scientists has taken a detailed look at the sophisticated visual system of the king scallop. They discovered this humble creature has a visual system that would impress even the most meticulous NASA telescope engineers, comprised of over 200 eyes that focus light using a system of concave mirrors and reflective crystals.
Biologists have known about this unusual visual system since the 1960s. This new study, published in the journal Science this week, is the first successful attempt to understand how it all works using various microscopic imaging techniques.
The eyes of humans, and the majority of other creatures with a fine sense of vision, work by light passing through a lens which focuses it onto the retina, a layer of light-sensitive cells. This is not the case with the scallop and a select few other creatures.
"In some rare visual systems in nature, mirrors are used instead of lenses to produce images,” the study authors wrote. “A remarkable example of such an eye is found in the Pecten scallop, which possesses up to 200 minute eyes lining the mantle tissue.”
The eyes are made up of a multi-layered mosaic of tiny mirrors and square guanine crystals, a highly reflective material found in the natural world. After light enters through a poppy-seed-sized hole, the layers of this mosaic work together to reflect light off these concave mirrors onto the retina above.
"The mirror forms images on a double-layered retina, to separately image both peripheral and central fields of view," the researchers wrote.
Once the retina receives this information, the team believes the scallop’s nervous system (after all, they don’t actually have a proper brain) then processes the images from its 200 eyes into a single image. This helps the scallop perceive the world with a complex three-dimensional view of the world with millimeter precision. All those eyes also mean they can view a wider horizontal area to keep an eye out for predators.
As a rather cool side note, the researchers on the project believe their work could even help develop more powerful telescopes. As is ever the case, nature is way ahead of us.