Photopsin absorb light at different wavelengths as retinal-bound pigments. Humans have three different photoreceptor proteins ("photopsin" or "cone opsins") which are found in cone cells and which are responsible for colour vision: George Wald received the 1967 Nobel Prize in Physiology or Medicine for his experiments in the 1950s that showed the difference in absorbance by these photopsins (see image). Photopsin Photopsins (also known as Cone opsins) are the photoreceptor proteins found in the cone cells of the retina that are the basis of color vision. Iodopsin, the cone pigment system in chicken retina, is a close analog of the "visual
Evolution of the eye behaviors have been identified, in two primary groups: Below 450 nm, associated with direct light, and above 450 nm, associated with reflected light. As opsin molecules were tuned to detect different wavelengths of light, at some point color vision developed when the photoreceptor cells used differently tuned opsins. This may have happened at any of the early stages of the eye's evolution, and may have disappeared and reevolved as organisms became predator or prey. Similarly, night and day vision emerged when photoreceptor cells differentiated into rods and cones, respectively. As discussed earlier, the properties of light under water differ from