What is inside the eye that makes us see colour? Why can't animals see in colour?
I like this question because we actually just went over this in my anatomy class, but it is actually a specific type of photoreceptors in a layer at the back of the eye called the retina that allow us to see in colour. These photoreceptor are called cones, and they are concentrated in the fovea (in the macula), which is the clearest point of vision in the back of our eye. Three different types of cones exist in the eye which are approximately sensitive to the red, blue and green regions of the visible spectra (wavelengths of light that we can detect). Also just to review so photoreceptors are a special type of neuron found in the back of the eye which can detect and are sensitive to specific wavelengths of light, which they then "transduct" into electrical potentials that can be sent to the optic nerve at the back of the eye, and then to a specific portion in the brain to process and relay information about the colour, and shape of the object we are looking at. There are two types of photoreceptors called "rods" and "cones", and the ones I have just described above (the cones) are the ones that help us see colour, while rods help us see shapes (work best in dim light). To help answer the second part of your question, and to help further explain what I have just stated above, I will refer you to this specific article: www.wisegeek.com/do-animals-see-in-color.htm So as the article states, the general rule (with many exceptions) is that most diurnal (daytime) animals see in color, and most nocturnal (night-time) animals either do not see in color, or not in as many wavelengths of colours that we see. This is because these animals, who that either lack or don't have enough (functioning) cone photoreceptors in the back of their eye, must rely on their rods for vision which are much more sensitive to bright light and do not distinguish between different colours as well as cones.
Answered By: Harman Sawhney