Cows can see in the dark due to having a mechanism that is known as tapetum lucidum. To put it as simply as possible, this is a reflective layer behind the retina that is able to increase the amount of light, so it is easier to see in the dark.
Let’s take a closer look at this mechanism.
How Cows See in the Dark – Tapetum Lucidum
Due to cows having a reflective layer located in the back of the eye, directly behind the retina, when light enters a cow’s eye, it bounces off the membrane making it easier to see in lowlight conditions. If you’ve ever wondered why some animals’ eyes appear to glow in the dark, it is because of this mechanism. When the pupil appears to glow in the dark, it is referred to as eyeshine.
Interestingly, many of the animals with a tapetum lucidum are nocturnal predators, which we definitely can’t classify cows under. The value of cattle having tapetum lucidum – and the reason why it evolved in herbivores – is that it makes it easier for them to detect and evade predators rather than be the predator themselves.
Other animals that have this mechanism include cats, dogs, deer, and horses. While it is found in both vertebrate and invertebrate species, as you might have noticed it is more common in mammals.
How Well Can Cows See in the Dark
While cows can certainly see better in the day than at night, they can see well enough to help them detect and evade predators, find good grazing spots, and avoid bumping into things.
As cows engage in what is known as polyphasic sleep, they sleep in small intervals throughout the day and especially the night, which means that being able to see at night when they are awake is a necessity.
As great as it is to be able to see at night, cows otherwise have pretty poor eyesight. Even though cows can see color and have a range of vision of more than 300 degrees, cows are unable to focus quickly and have poor depth perception.