Cat night vision is better than humans because cats have a high concentration of rods receptors. The cat’s retina is designed in a way for vision in low light conditions. The number of rods in cats retina are more in number than 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 biggest difference between cats and human’s vision is the retina. 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 cones receptors. As a result, humans can detect colors better whereas in 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.
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How pupil and tapetum lucidum helps during night vision?
Cat’s pupil’s shape is different from humans. The cat’s pupils are elliptical that are vertically oriented due to which cats can open it for a longer time period. The larger pupil allows more light and improves the cat’s vision during the night. The membrane of the cat’s eye called the tapetum lucidum. The tapetum reflects light within the eye itself and allow more light to reach the retina.
The large pupil and reflective tapetum maximize the light that reaches the retina, which is saturated with rods that are very effective at absorbing light. As a result of this, 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 types of cones that help them to 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 compare to humans. The cats have a 200-degree field of view whereas humans have 180 degrees. Their peripheral range is also greater and have six to eight times more rod cells than humans. That’s why cat night vision is better than humans.
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. Human retina has about 10 times more cones than cats. These cones function best in bright light that allows us to see bright and vibrant colors. Hence, cat night vision is better than humans but during bright light, humans can see better because of the higher number of cones.