Eye of the Tiger – Your Cat’s Vision Explained

Our cats perceive the world quite differently to us. Their senses operate with not only their own unique toolbox of anatomical equipment, but also on levels that we cannot imagine. Their smell and hearing are far superior to ours; their whiskers are highly involved in their sense of touch; and they lack the gene to appreciate sweet tastes the way we do(1) - which is just as well considering that chocolate is toxic for them! Unsurprisingly, their vision is also quite different to ours. Today we take a closer look at how cats see the world.

While cats are not completely colour blind, the range and intensity of colours that they see are believed to be smaller and more muted than that of humans, particularly in the red and orange side of the spectrum. This is because human eyes have about ten times more cones than cats do (2), and these receptors are involved in colour distinction and bright light vision.

Cats are also more near sighted than we are. While most people can clearly see objects at a distance of 30 to 60 metres; cats can only achieve this level of resolution at about six metres (2). This is due not only to their lower number of cone receptors, but also because cats do not have the same muscles as we do which work to change the shape of the lens in focussing (2).

Where feline sight leaves us far behind is in their specialised night vision, which was an important advantage for nocturnal hunting during their evolution.

The reason cats can see so well in the dark is due to numerous factors:

• Cats eyes have six to eight times more rod cells than ours (2). These receptors are responsible for vision at low light intensity.

• The shape of their eyes and large corneas help to gather light.

• Their pupils can dilate significantly to maximise the light entering the eye. While our pupils can undergo 15-fold changes in size, the vertical slits of cats can undergo 135-fold changes(3)!

• Lastly, cats’ eyes have a structure called a tapetum lucidum (primates don’t have this) - a reflective layer at the back of the eye, which essentially recycles light back to the light receptors. This mirror-like structure also accounts for the way a cat’s eyes glow in the dark!

It’s often said that the eyes are the window to the soul, and it seems true that cat’s eyes reflect not only their obvious beauty but also the myriad of ways that they are wonderfully and mysteriously different to us. Specialised ambush predators, their eyes are honed to detect movement in dim light; and evolved to focus on the prey they chase. They may stare at the same TV screens that we do, but what they see is quite different!.

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References

1. Biello, D. (2007, August 16). Strange but true: Cats cannot taste sweets. Scientific American. Retrieved from: https://www.scientificamerican.com/article/strange-but-true-cats-cannot-taste-sweets/

2. Ghose, T. (2013, October 16). Feline vision: How cats see the world. LiveScience. Retrieved from: https://www.livescience.com/40459-what-do-cats-see.html

3. University of California. (2015, August 7). Pupil shape linked to animal’s ecological niche. EurekAlert! Retrieved from: https://www.eurekalert.org/pub_releases/2015-08/uoc--psl_1080315.php