Seeing the Glory of God in Scallop Eyes
When the James Webb Space Telescope launches into orbit next year, it will use an array of mirrors to gather light from far away galaxies. Though this model was developed in the 1980s, scientists only recently discovered a similar design already in use in the eye of a humble sea creature, the scallop. That’s right—in 2019 we will be able to see distant galaxies the way a scallop might see them.
When you think of scallops, you probably picture glistening white, pan-seared medallions of delicate meat resting in a pool of butter sauce. But the part of the scallop served on your plate at the seafood restaurant is only the adductor muscle that closes and opens the scallop’s shell. If you could look closely at a live scallop, you’d see its shell frilled with tentacles and a layer of flesh on the inside rim, edged with little dots—its eyes.
Scallops Have Eyes?
Some species possess up to 200 peepers, mostly neon blue ones! In each eye, light passes through a lens and two retinas on top of each other before reaching a curved “mirror” in the back of the eye and reflecting back to the retinas. Rather than the lens, this “mirror” focuses the light the same way the segmented telescopes do.
In the late 1960s, a University of Sussex scientist discovered that the “mirror” in each eye was constructed of layered crystals, suggesting they were made of guanine, a DNA building block. However, not until recently when scientists eyeballed these eyeballs with newer techniques did they find that the guanine crystals are flat, square, and only a millionth of a meter wide. These crystals fit together in a grid with 20 and 30 grids stacked on each other and liquid filling the gaps between them. The exacting distance between the crystals and their gaps allows the mirror as a whole to reflect blue-green light, the overall color of the scallop’s environment, perhaps allowing the scallop to view a wider area for food or predators.
But that’s not all they discovered! Guanine crystals normally grow in prisms, not flat squares, indicating that the scallop shapes these crystals as they grow and form. Furthermore, according to an article in the Atlantic, scientists believe the scallop’s eye cells control “the growth of the crystals inside them, but they also have to communicate with each other to arrange themselves just so.”