The same is true of many prey animals in the wild.
In general, prey animals have their eyes on the sides of their heads, whereas predators’ eyes are more oriented to the front for pursuit.
There are of course many exceptions to this rule.
Our pupils are smaller and rounder which allows us to see a further distance in front of us, instead of all around.
What can goats see?
So, what exactly is a goat’s vision like with those rectangular pupils?
Well, it’s quite good.
It is thought that their rectangular pupils give them a full 360-degree view of their surroundings, which, again, makes spotting predators much easier.
Long, rectangular pupils also mean more light can enter the retina, giving goats excellent night vision.
Predators often like to hunt their prey under cover of darkness, so night vision is essential.
Goats can also distinguish a wide variety of colors.
They are not color-blind and can distinguish orange best among colors.
This helps them to notice predators who are lurking in the vegetation.
Also, interestingly, goats’ eyes rotate as they move their head to make sure their eyes are always level with the ground.
This helps them keep a constant awareness of their surroundings as they lower their heads to graze.
Modern, domestic goats, and indeed wild ones, are still however not particularly good at escaping from predators.
Don’t think that your goat’s excellent peripheral and night vision will be enough to keep it safe from dangerous animals.
Being herd animals, goats rely on safety in numbers, and on alerting each other of danger.
So, it is not only by having great peripheral vision but also by having lots of individuals present to warn of danger.
Are goats the only animals with rectangular pupils?
Rectangular pupils are far from common, but they are not unique to goats.
The main groups that employ this type of eye are equines and ruminants.
Horses, sheep, and deer all share this trait, and for many of the same reasons.
On the opposite end of the animal kingdom, octopuses also have rectangular pupils similar in appearance to goats.
This again regulates light coming into the retina and protects them from daytime glare.
Some species of toad also have distinctive rectangular pupils, again protecting them from glare and overexposure to light.
So, rectangular pupils are not unique to goats, but they are also not all that common either.
It is very interesting how they are shared by such diverse creatures as goats and octopuses.
Long, narrow pupils in all these animals allow them to regulate the amount of light coming in and not be blinded while also being able to see very clearly at night.
Why do humans have circular pupils?
Pupil shape can vary greatly across species, but why are our pupils so different to goats?
It can often be a matter of what time of day an animal is active.
Goats are very often active at night and need the ability to see in any lighting conditions.
Certain big cat species lack the slit pupils that domestic cats possess because they are entirely diurnal, meaning they are only active during the day.
Round pupils give cats like tigers the precision they need to quickly catch their prey, and who hunt primarily during the day.
Humans are, generally speaking, a diurnal species.
We are active during the day and take shelter at night, meaning we don’t need particularly good night vision.
Rectangular, horizontal pupils are more commonly possessed by the victims of these hunters.
If we can be called predators in a biological sense, human beings pursue prey for long distances.
We have an excellent ability to sweat which helps us regulate body temperature and run for a long time.
Our round pupils give us a more pinpointed view, allowing us to see further in the distance, but not as wide around.
Whereas goats have a 360-degree field of view, humans have only around 210. This is a very natural result of smaller, pinpointed pupils.
So, there are a lot of different reasons goats have rectangular pupils.
Pupil shape determines a great deal about how you see.
It isn’t as simple as just saying that goats are prey animals and therefore need to have better peripheral vision.
Domestic cats, which are predators, often share this rectangular eye shape at least in high light conditions.
So, goats not only have rectangular eyes to help them spot predators, although that is one big reason.
Rectangular pupils give them the widest possible field of view, meaning a herd can spot predators approaching from very far away.
Rectangular pupils also help goats regulate the amount of light that reaches their retina, so they can both see brilliantly during the night and not be blinded by the sun during the day.