Animal vision: The unexpected eyes of scallops

To most people, scallops bring to mind butter, pan frying and deliciousness, but there’s much more to these unusual animals than meets the eye. For a start, they do actually have eyes, as many as 200 of them depending on the species, and they are hardly typical.

Evolution has only produced three different ways of forming an image on the light sensitive retina. Of these three possible solutions, the lens, is the most common and will, of course, be familiar to all of us. However, a very small set of animals have evolved vision without the use of a solid, crystalline lens. One approach, taken by the ancient deep-sea mollusc nautilus, is to use its narrow pupil to form a dim and blurry image, much like the aperture of a pinhole camera. The other solution found in nature is almost unbelievable; rather than using a crystalline lens to focus light, some animals use mirrors instead. It is by using mirrors, rather than a lens, that scallops can see the world around them and with a surprising amount of detail.