Why Do Cat's Eyes Glow in the Dark?

Last reviewed on: 26th November, 2020

Although we may like to deem that animals perceive the world with similar colors and shadows as human beings, perhaps from a dissimilar angle, high in the sky similar to an eagle, or under the sea similar to a shark. The reality is that animal vision is dissimilar to our own and varies considerably among animal species.

Cats and other mammals that are effective in the day and night have pupils molded like vertical slits as that shape permits the pupil to alter size much faster than the round pupils we humans have. The smaller the pupil, the fewer light comes in, so our cats are much less possible to get blinded by abrupt changes in light levels than we are.

Human beings are different from tigers, or housecats for that matter, whose eyes are excellently well adapted to sight in the dark. This is because those cats have extra rods than cones in their retinas, not like humans, making cat's night and motion vision greater. Rods are the receptors that the eye uses for night viewing and abrupt movement; cones are used during the day and process color information.

Likewise, cat’s pupils are molded differently than those of humans because they are oval rather than round, which permits for a much bigger pupil size. Actually, the most remarkable feature of nighttime animals is the size of their eyes. The reason for this is that large eyes can assemble more ambient light.

Also, cat’s eyes open and close much quicker than do ours. And cats have an exceptional membrane on the back of their eyes known as the tapetum lucidum, meaning "bright carpet" that raises the amount of light trapped by the retina. The tapetum collects and re-radiates light back to the retina, donating the rods a second chance to absorb the image, so expanding their sensitivity to low light levels. While this light is reflected off the tapetum, the cat's eyes appear to glow.

The cat’s eye is in proportion larger than the human eye and features a layer of extremely reflective cells identified as the tapetum lucidum. The larger eye size and the tapetum coalesce to enable a cat to see movement and objects better in dim light.

The tapetum lucidum, positioned between the optic nerve and the retina, works like a mirror, reflecting the light and permitting the rods and cones another chance to pick up the limited amount of light accessible at night.This functional feature, which verifies to be an asset for animals who do their best hunting at sunrise and sunset, has been passed down to the domesticated cat from his ancestors.

The eyes of these animals are geared for low light vision; they include dogs, cats, cattle, deer, horses and ferrets. Though, humans and primates do not have the tapetum lucidum, and neither do misers because they are more active during the day, their retinas are invented for brighter light vision.

Posted by: Lusubilo A. Mwaijengo