A team of researchers took a closer look at the pupils of 214 representatives of the animal kingdom and discovered that there is a close relationship between the animal’s position on the food chain and its pupils. Apparently, predators have vertical pupils, while grazing animals have horizontal ones.
The research team included scientists from the University of Durham and Berkeley University who were keen on understanding the connection with an animal’s place in the pecking order and the anatomical particularities connected to it.
Different animals showcase different characteristics and while that isn’t news to most of us, the reason why may very well be.
Martin Banks, optometry professor at Berkeley University, together with Gordon Love, Center for Advanced Instrumentation director at Durham examined the pupils of predators and their prey, from Australian snakes to cats, dogs, rhinoceroses, goats, tapirs and even mongooses. They attempted to find the connection between the animal’s living and eating habits and their pupils.
Grazing animals, for instance, must always be aware of their surroundings. As such, in order to always maintain their eyes on the ground, their pupil rotates correspondingly when the animal drops its head. In the end, the pupil is always maintained horizontal, so that the animal experiences as few blind spots as possible and is capable of detecting predators as they approach.
In the past, researchers theorized that horizontal pupils contributed to expanding an animal’s horizontal view of the ground, yet the research team’s contribution has managed to construct a model proving how. Banks and his colleagues used computer models that reconstructed how differently shaped pupils benefited the animals they served.
Horizontal pupils, for instance, capture more light from the left and the right of the animal’s eyes. This is essential in order to detect predators approaching from all sorts of directions.
Vertical pupils, on the other hand, help predators efficiently estimate the distance between them and their prey by sharpening the perception depth and blurring out the surroundings.
Another important discovery that the team made was connected to the way that the eyes of predators active both during the day and during the night adapted to changing light characteristics. They needed to take advantage of dim light conditions and still hunt efficiently while still avoiding the glare of the sun during the day. As such, the pupils of such animals could change their area 135-fold (in the case of the domestic cat) and even 300-fold (in the case of the gecko).
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