S is for (P)sychedelic Scallops

Take a trip down to Sandy Hook and you'll find lots of cool things. There are horseshoe crabs, razor clams, oysters, and moon snails. Hidden among these creatures, in the deep blue sea, lies the best bivalve ever: the king scallop. Many of you have probably encountered this beauty on a plate seared in butter but between its two shells hides wonderful mysteries. But before we get into the magicalness of scallop anatomy just take a moment to watch how funny swimming scallops are.

They swim by taking water into their shells and then expelling it rapidly

                                                     

But the real shocker about scallops is that they can see!!!! What?!?!?!?!?!? And...... they have roughly 200 eyes each. Each eye is located on the end of a tentacle that can extend out of the shell. All the eyes are found on the mantle, the fleshy part inside the rim of the shell. Although each eye is the size of a poppy seed, they contain a lens, two retinas, and a mirror.

 Each blue dot is an eye

So how do these eyes work? Because they are so tiny it was a mystery until an Israeli team used super fancy microscopes last year to figure it out. Light passes through the lens and retina because they are pretty see-through. The light then hits the tiny mirror in the back of the eye and is reflected onto the back of the retinas. One retina focuses light to see the periphery while the other retina focuses what is immediately in front of the scallop. The periphery vision is used to find feeding grounds while the immediate vision is used to detect predators.

One of the newest breakthroughs has been to analyze the mirror used in scallop eyes. Human eyes only use a lens and retina so why use a mirror? Lenses are only good for focusing a very limited type of light while mirrors can reflect many more types, allowing the scallop to interpret more of its surroundings. The mirror is made up of guanine, one of the DNA bases. Molecules of guanine are assembled into tiny, flat squares that are arranged like tiles into a flat bottomed bowl structure. The mirror is about 30 layers thick with fluid between the layers. This structure allows the light to be redirected back to where it came from. Because of the structure these eyes are very good at interpreting blue light, the predominant light in the marine environment.

   

 A close-up of scallop eyes

The mirror technology that has been discovered in scallops could help......... space technology!! Telescopes are being designed with the same mirror idea to help scientists see into deep space. Isn't this cool? And to think these majestic beasts were in our own backyard this whole time!