When Form 8865 Contains 2023-2024

We usually think of scallops as tasty pan-seared delicacies or the classic shape of clipart seashells. However, last week biologists revealed that they're worthy of way more than a special spot on the menu. Their visual system is amazingly complex and includes up to 200 telescope-like eyes. Most eyes, from the fancy compound eyes of bees to our own simple ones, focus light with a lens onto a retina which contains light-sensitive photoreceptors. Scalloped eyes, on the other hand, use mirrors to do this focusing, which is why sometimes people compare them to telescopes like Hubble. Despite their tiny size, this much had been known for half a century thanks to a British vision researcher. But what the mirrors are made out of and exactly how sight worked for the scallops remained a mystery. That's mostly because their eyes are only about a millimeter big, and every time scientists tried to prepare the delicate eye tissue for a microscope, the samples dried out and fell apart. Enter cryogenic scanning electron microscopy or cryo-SEM. The technique uses liquid nitrogen to quickly chill samples, allowing researchers to keep tissues intact and hydrated. Reporting in the journal Science, a team used this method and discovered that scallop eye mirrors are made out of guanine. You might have heard of guanine because it's one of the four bases that makes up DNA. But crystals made of guanine have weird optical properties that many organisms use to survive, like what makes fish scales look iridescent or shiny. In scallops, the guanine crystals are in the shape of square tiles. These tiles are stacked 20 to 30 sheets thick, each layer separated by a bit of cytoplasm, and they're arranged to form a curved mirror at the back of each eye. This is similar to how segmented mirror telescopes,...