Scallops’ Eyes Are Like Human Freckles

Scallops have up to 200 eyes – which develop in the same way as our freckles – say researchers in Israel.

They believe the same stem cell that controls the production of melanin for human hair, eye, and skin pigmentation also controls the way the oyster-like shellfish develop mirrored – or crystalline – eyes.   

Researchers at the Ben Gurion University of the Negev came to the discovery while they were studying the way juvenile scallops generate their unique eyes. 

Scallops use each of their eyes as a mirror instead of a lens to focus light. These mirrors are made of guanine crystals, a highly-reflective material that can be seen from fish scales to chameleon skin. 

Under a microscope, guanine is usually bulky – but the crystals in the scallop’s eye are perfect squares that, like a telescope mirror, create a smooth surface that minimizes optical distortions.  

“This natural production far exceeds what chemists are capable of reproducing synthetically at the moment,” explains Dr. Benjamin Palmer, of the Department of Chemistry.

“But they provide intriguing strategies for controlling the properties of synthetic crystalline materials which may be used for future pigments that do not rely on harmful chemicals, but on natural processes instead.”

The researchers used a new microscope that was donated to them to see the square-shaped guanine crystals, which was impossible 50 years ago when research on scallop eyes began. 

Their research was published in Nature Communications.