New look inside the sea creature’s eyeballs reveals their unusual workings
There’s stiff competition for the most elaborate eyeballs in the animal kingdom, but a mollusk that turns up on dinner plates might be a finalist.
Each of a scallop’s eyes — it has up to 200 of them, each about a millimeter in diameter — contains millions of perfectly square, flat crystals that build up into a mirrored mosaic, new research shows. And that shiny surface is curved in a way that lets a scallop focus light onto two different retinas.
Scientists have known for a long time that scallop eyes are unusual. In the 1960s, biologist Michael Land showed that each scallop eye uses a mirror to focus light into images, while most other eyes use lenses (SN: 5/28/16, p. 22). That natural mirror is made of crystals of guanine, Land determined — better known for its job as one of the four nucleotides that make up DNA. At the