Cat night vision is better than humans because cats have a high concentration of rod receptors. The cat’s retina is designed for vision in low-light conditions. The number of rods in a cat’s retina is more in number than in cones. Rods absorb light in a more effective way than cones. Cones are responsible for absorbing color and creating the perception of light, which is more limited in cats than humans.
Photoreceptors-Rods and Cones
The retina is the biggest difference between a cat’s and a human’s vision. Cat night vision is better due to the high concentration of rods and low concentrations of cones receptors. On the other hand, humans have a high concentration of cone receptors. As a result, humans can detect colors better, whereas in the dark, they can’t see well. Cats can’t see rich colors but have a higher tendency to see in the dark. Due to the higher number of rods in the retina, cat night vision is better than humans.
How do pupil and tapetum lucidum help during night vision?
Cat’s pupil’s shape is different from a human’s. The cat’s pupils are vertically oriented elliptical, which cats can open for a longer period. The larger pupil allows more light and improves the cat’s vision during the night. The membrane of the cat’s eye is called the tapetum lucidum. The tapetum reflects light within the eye, allowing more light to reach the retina.
The large pupil and reflective tapetum maximize the light that reaches the retina, which is saturated with very effective rods at absorbing light. As a result, signal transduction occurs along the radial nerve to produce an image in the cat’s brain during the night.
Color vision and field of view
Humans are known as trichromats because they have three cones that help them see red, green, and blue. Cats are also considered trichromats but not in the same way that humans are. A cat’s vision is similar to a human who is color blind. They can see shades of blue and green, but reds and pinks can be confusing. These may appear more green, whereas purple can look like another shade of blue.
Cats have a wider field of view as compared to humans. The cats have a 200-degree field of view, whereas humans have 180 degrees. Their peripheral range is also greater; they have six to eight times more rod cells than humans. That’s why a cat’s night vision is better than a human’s.
Three types of cones in humans allow them to see a broad spectrum of colors, with high sensitivity for red, green, and blue. The number and distribution of each type are different. In behavioral tests, cats couldn’t see the full range of colors like most humans. The human retina has about 10 times more cones than cats. These cones function best in bright light, which allows us to see bright and vibrant colors. Hence, cat night vision is better than humans, but humans can see better during bright light because of the higher number of cones.