Dec 1, 2017

Mirrored eyes give scallops extraordinary sight

Three eyes of Pecten Maximus. Photo: Dan-Eric Nilsson / Lund University

Little known fact: Scallops have eyes, and they're made out of crystals. In a new paper, scientists describe the sophisticated structure of the bivalves mirrored eyes, which could offer inspiration for engineering artificial light-collecting materials.We only eat a small part of a scallop so we rarely see their shells, let alone their eyes. But they have up to a hundred laid out like a necklace of tiny, iridescent, blue-black pearls nestled in the tentacles that line their shell.How they work: Those eyes are relatively unique in the animal kingdom. In the same way a radio telescope uses a large, reflective dish to gather light and centers it on a sensor, scallop eyes have a mirror that focuses light on their retina."It's a small, compact visual system. It's hard to form an image in water with such a small eye," says study author Benjamin Palmer of the Weizmann Institute, who reported in the journal Science that the reflective film on scallops' eyes is formed from stacks of semi-rectangular crystals of guanine, one of the four chemicals that make up DNA."It's amazing to look at the control these animals exert over the crystallization process," Palmer tells Axios.Normally, guanine doesn't like to form square crystals. Attempts to build such crystals through traditional chemical means are clumsy, but the scallops accomplish it easily. By studying them, and other similar creatures, scientists might learn better ways to create efficient, light-collecting molecules like these in the lab for materials science applications.

Yes, but: Although their eyes are elegant, scallops are not. If they see a predator they swim rapidly away like underwater Pac-Men.

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