Victim's mark: Scientists explain why sheep have rectangular pupils.

Throughout history, our planet has been home to an incredible number of living species: some have long since gone extinct, while others continue to thrive and astonish scientists. Take sheep, for example. If you closely examine the eyes of these animals, you may notice something unusual — rectangular pupils, as noted by IFLScience.

Sheep are ruminant mammals that belong to the same group as deer and antelopes, characterized by their love for chewing. Another common trait among these animals is that they often need to flee when a predator is nearby. This is where their rectangular pupils come into play.

According to Marty Banks, the lead researcher at the Visual Perception Laboratory at the University of California, Berkeley, horizontal pupils are associated with prey animals. Studies have shown that prey animals typically have their eyes positioned on the sides of their heads, rather than at the front like humans and other predators.

Researchers discovered that vertically narrow pupils enhance the ability of animals to see horizontal contours. They suggest that this pupil shape aids animals in placing their feet on the ground as they attempt to escape from predators.

It is worth noting that the animal kingdom showcases a rich variety of pupil shapes. For instance, cats have vertical pupils that help them remain hidden, while larger predators, such as humans, generally have round pupils.

The pupils of sheep may seem strange, but according to scientists, they are not the most unusual in the animal kingdom. For example, cuttlefish have pupils that sway in a wavy pattern. Meanwhile, mongooses possess thread-like pupils similar to those of sheep.