Scientists have been learning some crazy new things about eyes and sight. We tend to have a very narrow idea of what “seeing” means. When you hear the word eyeball you picture the “camera style” eye belonging to vertebrates like humans (light enters through the lens and cornea and then is focused at the back of the eye), but we are learning the world of vision is fantastically diverse. For decades scientists focused their vision research mostly on a small group of animals including humans, cats, and goldfish, but now the research is beginning to broaden and new types of “eyes” are being discovered all the time. In fact, some critters like sea urchins and select microbes use their entire bodies as eyes, and are able to sense light and the direction it is coming from. Others like butterflies, octopi, and scallops have skin or scales that are photosensitive and able to detect light. During a study on the eye spots (a small grouping of photo receptors) of the Asian swallowtail butterfly, scientists discovered that, even though they have highly evolved compound eyes, when the eye spots were removed the butterflies struggled to mate and lay eggs. In octopi, light can trigger color change reactions in skin that has been detached from the animal, showing that the photo receptors in the skin function independently of the octopus’s brain.
Studying these simpler forms of vision help us understand how our own complex eyes may have evolved. There is still so much to learn about vision and the amazing way that the creatures around us perceive the world. And as for sea urchins being giant eyeballs with spikes? I think that is pretty awesome!
Want to learn more? Visit https://www.sciencenews.org/article/some-animals-%E2%80%98see%E2%80%99-world-through-oddball-eyes?tgt=nr
May 27, 2016