Sea-dwelling mollusks called chitons have armor-plated eyes embedded in their shells, and this incredible feature could provide a model for protective armor that could be used by the army and workers exposed to dangerous conditions.
The chitons, or Acanthopleura granulates, have hundreds of these armored eyes on the surface of their shells, MIT reported. Unlike most eyes in the biological world that are made primarily of protein, these eyes are made of the mineral aragonite, but can still form focused images.
"[These mineral-based eyes] allow the animal to monitor its environment with the protective armor shell. The majority of the shell is opaque, and only the eyes are transparent," said recent MIT graduate and Harvard postdoc Ling Li.
Chitons live in the intertidal zone where they are exposed to both water and air. This means the potato chip-sized animals' eyes must be able to work under both of these conditions. The scientists demonstrated the chiton's eyes are able to focus light and form images within the photoreceptive chamber underneath the lens in both air and water. To make their findings, the researchers used high-resolution X-ray tomography equipment and material characterization techniques to study the 3-D "architecture" of the eyes. In the past, researchers had believed chiton eyes were too small to form focused images. The researchers hope these new findings will one day lead to the development of bio-inspired materials to provide both physical protection and optical visibility at the same time.
"High-resolution structure and property studies of the chiton system provide fascinating discoveries into materials-level tradeoffs imposed by the disparate functional requirements, in this case protection and vision, and are key to extracting design principles for multifunctional bio-inspired armor," said MIT professor Christine Ortiz.
The findings were published in a recent edition of the journal Science.