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Predator & Prey Pupils

August 12, 2015

Differences in animals’ pupil shapes distinguish predators from prey.



12132772093_72a859746e Susanne Nillson CC BY-SA 2.0 via flickr_z

Cats have vertical pupils. (Susanne Nillson CC BY-SA-2.0, via flickr)

Pupil patterns. I’m Bob Hirshon and this is Science Update.

Round in humans, vertical in cats, horizontal in horses; why are pupils shaped differently? Martin Banks at the University of California, Berkeley studied over two hundred animals to find out.

MARTIN BANKS (University of California, Berkeley):

We showed that there really is a strong relationship between the kind of pupil an animal has and what their ecological niche is.

15321360491_20f49ed76e_z Gordon Milligan CC BY-s.o, via flickr

Goats have horizontal pupils. (Gordon Milligan, CC BY-2.0, via flickr)


The findings, published in Science Advances, reveal that animals with vertical pupils like  crocodiles are mostly predators that ambush their prey; vertical slits help gauge distances so they pounce accurately. Taller animals, like humans, tend to have round pupils. Advantages of vertical pupils disappear with height, and these predators chase prey rather than pounce. Finally, animals with horizontal pupils like horses and sheep are nearly always prey; horizontal openings provide wider panoramas to see approaching predators. I’m Bob Hirshon, for AAAS, the science society.