The eyes are a very powerful tool for successful development in nature. The iris contracts or dilates depending on the ambient brightness. The window through which light penetrates is what we know as the pupil. UC Berkeley focused on the latter in a recent study. Why do animals have different types of pupils? What is the relationship between pupils and animal survival?
Adapted pupils
They analyzed the pupil shape of over two hundred different terrestrial species. The conclusion? Pupil morphology was directly related to the animal’s ecological niche.
The vertical slit pupil was observed to be a general pattern of predators. For example, cheetahs. It allows them to control the entrance of light much better. Also, to gauge with enormous precision the distance separating them from their prey.
Gazelles, like most ungulate mammals, have horizontally arranged rectangular pupils. Thus they see more clearly what is on the ground plane. And they calculate the precise moment when they have to start running. This generates a panoramic vision with which they are able to detect the presence of predators. And it helps the eye to have less glaring overhead light.
Evident relationship
Some herbivores have taken an additional evolutionary step. They present elongations in the upper part of the eye, the so-called corpus nigra or iridic granules. They act as a visor. They minimize the entry of light from above and prevent glare.
Their eyeballs are located on both sides of the head. Therefore, they have a much larger field of vision.
There are animals, such as wolves, that do not require such a complex optical apparatus. Their hunting tactic is diurnal and consists of exhausting their prey. For this reason, like us, they have rounded pupils. It is clear that evolution has determined these characteristics. Pupils and animal survival are closely related.
