How do dogs see colors? - briefly
Dogs have dichromatic color vision, which means they can distinguish blue and yellow hues but struggle with red and green shades. This is due to their retinal cones, which contain only two types of photopigments compared to humans' three.
How do dogs see colors? - in detail
Dogs possess dichromatic color vision, which means they can distinguish between two primary colors: blue and yellow. This contrasts with human trichromatic vision, where we perceive three primary colors: red, green, and blue. The difference lies in the structure of the photoreceptor cells in the retina, specifically the cones, which are responsible for color perception.
Humans have three types of cone cells that contain different photopigments sensitive to short (blue), medium (green), and long (red) wavelengths of light. Dogs, on the other hand, have only two types of cone cells, one containing a photopigment sensitive to short wavelengths (blue) and the other to medium wavelengths (yellow). This dual system allows dogs to see shades of blue and yellow but not green or red.
Additionally, dogs have more rods than cones in their retinas, which enhances their ability to see in low-light conditions. However, this increased number of rods comes at the cost of reduced color perception. The rod cells are responsible for detecting light and dark but do not contribute to color vision.
The lack of red receptors in dogs' eyes means they perceive shades of red as different shades of gray or brown. Similarly, green objects appear as various shades of yellow. This limitation does not seem to hinder their ability to navigate their environment effectively, as their sense of smell and hearing are far more developed than their color vision.
In summary, while dogs do see colors, their perception is significantly different from that of humans. Their dichromatic vision allows them to distinguish between blue and yellow but not red or green. This unique visual system is adapted to the needs of their species, prioritizing low-light visibility over a wide color spectrum.