A goat’s rectangular eyes are cool to look at, but do they serve any special purpose? These rectangular pupils have a lot of cool features that go along with them. From aiding in their search for predators to letting them look at the sun.
Goat’s eyes have rectangular pupils to provide them with a wide, panoramic field of vision. This helps them to spot prey long before a circular pupil would. Rectangular pupils also provide several other advantages including the ability to not be blinded by the sun.
Continue to learn a bit about evolution, the perks and disadvantages of pupil types, and how they are affected by the type of animal that evolved that pupil.
Goat’s Pupils In Action
Goats have rectangular pupils because they are prey animals. In a study done by the University of Berkley, Dr. Martin Banks notes that if you are a prey animal that lives on land “you’re very likely to have a horizontal pupil” because you need to be able to spot predators quickly.
This means that goats aren’t the only animals to have square pupils. They have some good company. Deer, horses, cows, and moose all have similarly shaped pupils, and all of them share the same purpose; To protect the animal from prey.
Rectangular pupils provide a wide panorama of vision. Much wider than humans have. So while a human has a field of vision of about 120 degrees, a goat has a field of vision of about 300 degrees. Making them more than twice as likely to spot a moving animal than a human would be.
A goat’s square pupils also help prevent the sun from blinding them. Their square pupils limit the amount of light that comes in from above them by giving the goat control over the amount of light that is allowed to come in.
This feature of their famed square pupil allows for the goats to have some great night vision. It’s not fabulous night vision, though it is much better than a human’s. It’s good enough to keep them safe from predators at night.
An eye’s evolutionary purposes are endless. One of the most important though is to catch sight of incoming predators before the predator catches the prey. While a goat’s pupils are remarkable, they alone cannot serve this purpose. There needs to be additional evolutionary help from the entire eye and socket.
Rotating Eyes
Having a 300-degree vision is an incredible feat in and of itself. You need to use it all the time for it to really be useful.
If a goat could only see its full field of vision while it was looking up (not eating) then predators could sneak up very easily very often. This would not work out very well for the goat. Luckily, this isn’t the case. A goat’s eye will rotate 50 degrees, staying parallel with the ground as it moves its neck up and down for eating.
For comparison, a human’s eye can rotate about five degrees before we start straining ourselves and causing damage.
This ability is crucial for the goat to be able to see its surroundings constantly. If the goat loses sight of its surroundings it risks the intrusion of prey and will be caught off guard when it needs to get running. This also lets the goat see higher off the ground than otherwise possible while it is eating due to the ability to control the incoming angle of the sunlight.
So basically, unless you are very adept at sneaking (either a cat or a ninja), or know your goat’s blind spots very well, sneaking up on a goat is a challenge that might leave you the loser. It’s easier to scare them into fainting.
This is not unique to goats either. A majority of grazing animals have this ability. Including all those listed above.
Types Of Pupils
Goats and most grazing prey animals have a square pupil that allows them to see well at night and with such an incredibly wide view that people once thought it to be 360 degrees. Despite all of these advantages that a goat eye provides, there is a lot of fierce competition out there.
For example, a coyote (one of the biggest goat predators) has a pupil that is a verticle slit. This is distinctive for ambush predators that are close to the ground. This offers great depth-perception while moving and a very focused field of vision.
The other most common pupil is the round pupil. These are commonplace in predators that have heads high off the ground (like humans and large cats) There are a few exceptions to this rule. The elephant being one.
Let’s talk about why this is. Goats (and other grazing prey animals) have their square pupils (sometimes more oval-shaped) to ensure they can see predators long before the predator is close. Their wide field of vision gifts them with sure footing while running away because of their over-lapping high definition view of what’s ahead of them.
Ambush predators need their verticle slits to not lose sight of their prey while hunting them. Far distances tend to blur out so they have an excellent closeup vision.
Round pupils are a bit of a compromise. You have them, you know that you can identify things twenty or thirty feet away, and have a good general idea of what’s in your peripheral vision. Yet you have no idea if that new black shape near the ground is a dog or trash if you don’t look directly at it or have seen something similar to it before.
To Sum Up
Goats have square pupils because they are grazing prey animals. These marvelous little pupils allow them to see in a 300-degree field around while rotating to allow them this great field of view while their neck is bent downwards.
Their pupils offer a wonderful depth-perception in their peripheral vision and an all-around awareness of their surroundings without preventing them from any big setbacks. They do not see so well far away though.
Luckily, they do limit the amount of sunlight that enters into the pupil. Yet they also enhance any light for excellent nighttime sight.
I’ve included a short little video summing up a lot of these points. I encourage you to give it a watch.