That dogs aren’t colorblind? Not completely, anyway. They’re dichromats (pronounced with a long ëa’), with two types of cone cells in their eyes, able to see two color wavelengths. Most mammals have this kind of vision. Humans, on the other hand, are trichromats, with three types of cone cells, enabling us to see the red, green, and blue wavelengths.
Conversely, many insects, arachnids, and non-mammalian vertebrates are tetrachromats, able to see ultraviolet light. Some birds and insects are even pentachromats, able to see five different color spectra. And the mantis shrimpóconsidered to possess the most complex visual system of allócan perceive over a dozen, including infrared, as well as polarized light.