Humans have three types of cone receptors in their eyes, which make color vision possible (see the excursus on the human eye). Because of this, humans are called trichromats (from Greek “tria chroma”, meaning “three colors”). The cones on the retina are sensitive to red, green and blue light, and together they let us see many mixed colors. Want to learn more about color mixing? Check out this excursus.
Dogs, however, have only two types of cones and are called dichromats. They can see colors made from yellow and blue, but they cannot see true red. Move the slider to see how this colorful bouquet looks to a dog.
Many bird species are tetrachromats. They have four different types of cones in their eyes. This means birds can see more colors than we can! One of these cone types is especially sensitive to ultraviolet (UV) light. This helps birds find food, because insects and ripe fruits often reflect UV light and are easier for birds to spot.