Eye to Eye

This is my cat, Chase. When she’s in bright sunlight her pupils are thin vertical slits. I recently read a paper by Martin Banks, et al. about the pupils of terrestrial animals and why they are different shapes. Click here for the paper. The vertical pupils of cats, it turns out, are typically seen in ambush predators that are active day and night; hunters that sit still at close range and then pounce (which describes Chase to a T). The  pupil shape gives the cat a special kind of depth of field that allows her to estimate distances without moving her head. Stealthy! Click to enlarge.

This goat, on the other hand, has eyes on the sides of his head and horizontal pupils. The study found that’s a common arrangement for grazing animals that are always watching to see who might be sneaking up on them. According to the study, the horizontal pupils help light to enter the eye from in front and behind but not so much from above and below, giving the goat a nice panoramic view of its surroundings and some help evading danger.

Any questions?