Why do animal eyes have pupils of different shapes?

Banks, Martin S.; Sprague, William W.; Schmoll, Jurgen; Parnell, Jared A.Q.; Love, Gordon D.

Abstract

There is a striking correlation between terrestrial species’ pupil shape and ecological niche (that is, foraging mode and time of day they are active). Species with vertically elongated pupils are very likely to be ambush predators and active day and night. Species with horizontally elongated pupils are very likely to be prey and to have laterally placed eyes. Vertically elongated pupils create astigmatic depth of field such that images of vertical contours nearer or farther than the distance to which the eye is focused are sharp, whereas images of horizontal contours at different distances are blurred. This is advantageous for ambush predators to use stereopsis to estimate distances of vertical contours and defocus blur to estimate distances of horizontal contours. Horizontally elongated pupils create sharp images of horizontal contours ahead and behind, creating a horizontally panoramic view that facilitates detection of predators from various directions and forward locomotion across uneven terrain.

Citation

Banks, M. S., Sprague, W. W., Schmoll, J., Parnell, J. A., & Love, G. D. (2015). Why do animal eyes have pupils of different shapes?. Science Advances, 1(7), Article e1500391. https://doi.org/10.1126/sciadv.1500391

• Journal Article Type: Article
• Acceptance Date: Jun 28, 2015
• Online Publication Date: Aug 7, 2015
• Publication Date: Aug 7, 2015
• Deposit Date: Dec 15, 2015
• Publicly Available Date: Dec 15, 2015
• Journal: Science Advances
• Electronic ISSN: 2375-2548
• Publisher: American Association for the Advancement of Science
• Peer Reviewed: Peer Reviewed
• Volume: 1
• Issue: 7
• Article Number: e1500391
• DOI: https://doi.org/10.1126/sciadv.1500391
• Public URL: https://durham-repository.worktribe.com/output/1416609