Meet the mollusk with eyes in its shell

A new study has confirmed that a species of mollusk, the same family of animals that includes snails, slugs, and octopuses, does in fact have eyes directly in its shell. The Acanthopleura granulata, or more commonly known as the West Indian fuzzy chiton, has a hard outer shell to protect its soft insides, but that armor is also outfitted with hundreds of microscopic lenses that let it see its surrounding environment, and be aware of incoming attacks.

Published this week in the journal Science, the research explains that the mollusk's eyes are actually made of the same material as its shell — the mineral aragonite. This is significant as it differs from the eyes of almost every other species, which are made of proteins.

The paper, authored by Ling Li, a MIT graduate and Harvard postdoc, also revealed that the species' eyes are capable of producing a real image, making them not that different human eyes. Their ceramic lenses are able to focus light onto a retina with photoreceptors.

To determine just how clear an image the eyes were capable of, the scientists removed a few from the mollusk's shell and put them under the microscope. They found that while the lenses could focus a crisp image, the retinas could only produce tiny, pixellated images.

Despite this, the vision is more than enough for the chiton, as they just need to be aware of nearby predators. Once threatened, they simply use nearby rock to hide from danger. "The only thing it can do is clamp down onto the rock so that predators cannot eat it. Once they are clamped down, it is actually very difficult to dislodge them," Li said.

VIA Motherboard

SOURCE Science