When it comes to vision, animals are not all one in the same.
Not only is animal vision significantly different than ours, but there are different types of vision in the animal kingdom as well.
Let’s break this down a bit further.
Anatomy of the Eye
Firstly, it is important to understand the anatomy of our own eyes in order to understand how animal vision is different.
Specifically, we should pay attention to the cones and rods in the eye.
Both cones and rods are photoreceptors. However, they each serve a different purpose.
Rods are more numerous (~120 million) and more sensitive. They are responsible for our ability to adapt to the dark (Hyperphysics). Cones (~6 to 7 million) are more sensitive to color and are concentrated in specific regions within the eye (Hyperphysics). Further, cones can be broken down into three specific types, which allow us to distinguish red wavelengths from green and blue wavelengths from yellow (LiveScience).
Other mammals, including dogs and cats, only have two types of cones in their eyes. Therefore, their eyes can only distinguish blue from yellow, but not red from green.
What’s even more interesting is that the optical anatomy of dog and cat eyes is similar to that of color blind people. This similarity is why many people say that dogs and cats are color blind. When, in fact, their anatomy is simply standard for their species, but similar to color blind people.
Further, both dogs and cats have more rods than we do, which enables them to see better at night.
Have you ever tried to take a picture of your dog or cat and their eyes are colored with a weird reflection?
Allow me to introduce to you….the Tapetum Lucidum (one of my favorite words I learned in college).
This reflection mechanism allows light to reflect back through the retina increasing light reception by photoreceptors.
Meaning, that dogs and cats see better at night not only due to the increased number of rods but also due to the increased reception of light thanks to their tapetum lucidum!
Predator vision versus Prey Vision
Now that we have a more thorough understanding of the anatomy of the eye, it is time to take a look at the different types of vision among mammals.
Predators have what is called Binocular Vision, which means that they use their two eyes together. This type of vision only allows for 120 degrees of vision, but improves depth perception due to the overlap of the two eyes. Predators have less of a need to see what is going on behind them, and more of a need to detect depth perception.
Prey animals, like cattle, for example, have eyes set on either side of their head.
The position of their eyes allows them to see up to 300 degrees around them. However, many prey animals have blind spots directly in front of them and directly behind them. Additionally, they have to move their head up or down to perceive the depth of an object (LifeandScience.org).
In conclusion, dogs and cats can see better at night due to the increased number of rods and their tapetum lucidum. Additionally, the positioning of their eyes is consistent with predator vision. However, some pocket pets you have at home may have prey vision instead, which may explain why they are startled more easily.
This post was very fun for me to write. I remember learning about vision in my animal science class like it was yesterday, and this information is often something I repeat whenever possible.
Did you find this post interesting?