Which Of These Animals Has Rectangular Pupils?
Many a curious child has been startled at a petting zoo when a hungry goat turned a keen, and rather odd looking, eye toward them. Goats, as well as a handful of other animals around the world, have horizontally-oriented rectangular pupils that look quite different from the round pupils found in humans and many other animals.
Why rectangular? Why horizontal? After years of speculation researchers finally determined, both through field observations and modeling, that prey animals, like the goat, have horizontal-rectangular pupils in order to create a huge field of vision while simultaneously shielding themselves from bright sunlight while grazing. A grazing goat has a remarkable 320 degrees of vision thanks to the combination of eye placement and pupil shape. Further, the shape of the pupil helps them see the grass in front of them and predators approaching from the sides with great clarity without flooding their eyes with bright overhead sunlight.
Image courtesy of Jo Naylor.