Horses and Sheep and their amazing Eye Movements

New research led by scientists at the University of California, Berkeley, suggests that the shape of some animals' pupils could reveal whether one is hunter or hunted.
An analysis of 214 species of land animals shows that a creature's ecological niche is a strong predictor of pupil shape. Species with pupils that are vertical slits are more likely to be ambush predators that are active both day and night. In contrast, those with horizontally elongated pupils are extremely likely to be plant-eating prey species with eyes on the sides of their heads.
The study, led by vision scientist Martin Banks, UC Berkeley professor of optometry, in collaboration with the United Kingdom's Durham University, presents a new hypothesis as to why pupils are shaped and oriented the way they are.