Eyes of the scallop
Scallops see with an array of up to 200 eyes that use mirrors instead of lenses, like a reflecting telescope.
Researchers have obtained a detailed view of a scallop’s visual system - a sophisticated arrangement of up to 200 eyes they say is strikingly similar to a reflecting telescope. Just as the complex optics of other animals, like lobsters, have informed telescope design, these results may pave the way to the construction of novel bio-inspired optical devices for imaging and sensing applications.
Most animals use lenses to focus light onto their retina, a light-sensitive layer of tissue coating the inner portion of the eye, though certain marine organisms (including the Pecten scallop) have adopted mirrors to create images.
Benjamin Palmer and colleagues at the Weizmann Institute of Science in Rehovot, Israel, investigated the complex organization of the scallop’s mirror. Using various microscopic imaging approaches, the scientists found that spatial vision in the scallop is achieved through the mirror's layered structure located at the back of each eye, which is fine-tuned to reflect wavelengths of light that penetrate its habitat.
What’s more, the mirror is tiled with a mosaic of square-shaped crystals, minimizing surface defects for a clearer picture. The mirror forms images on a double-layered retina, to separately image both peripheral and central fields of view. The researchers note their work demonstrates the remarkable control the scallop exerts over the growth and arrangement of crystals to make a highly reflective mirror capable of forming functional images.