It was really interesting to learn about how color vision is so different in shrimps! As Professor Conway explained in class last week, human color perception is the result of lights absorbed in three different cone photoreceptors in the retina. These photoreceptors are each sensitive to different wavelengths of light. However, although these cones enable us to see millions of different combinations of light, they do not let us distinguish between a color as it appears in natural light (e.g. the yellow in the visible spectrum) and the same color as it appears as a mixture of two colors (e.g. yellow as a mixture of red and green). Thus it as really interesting to learn that although shrimps have 12 different cones, they can actually perceive fewer colors than humans because the neurons responsible for understanding photo-reception in their brains are unable to merge/combine the different colors the way humans can.
This article got be interested in understanding how animals perceive color. I was surprised to learn that dogs do not only perceive the world in black and white – they have 2 different cones in their retinas (blue and yellow) so they can still see color, but in a more limited way than humans. Dogs have been associated with color blindness because color blind individuals also have just 2 cones. Dogs use different cues to distinguish between colors so what most people see as red, dogs see as dark brown, while green, yellow and orange all look “yellowish.” Something that looks blue-green to humans — for example, the sea — looks gray to a dog, and purple objects just look blue.
Source: http://www.livescience.com/46565-are-dogs-colorblind.html