By Nicholas St. Fleur
Why do the eyes of some animals, including goats, have horizontal-shaped pupils, while others, such as rattlesnakes and domestic cats, have vertical slits?
It is a question that has longed intrigued researchers, and a study of 214 species published Friday suggests the answer may be strongly linked to giving animals a survival edge: vertical pupils and circular pupils help certain predators hunt, while horizontal pupils help other species spot predators from afar.
Not all vision scientists accept the researchers’ hypothesis, however, citing examples of animals that do not fit cleanly into these classifications.
The research, which was conducted by a team of scientists from the University of California, Berkeley, and Durham University in Britain, was published in the journal Science Advances.
The team used computer models based on a sheep’s eye to support theories about why horizontal, vertical and circular pupil shapes benefit different animals.
When the model’s pupil was horizontal, more light could be captured from the left and right of the eye, not surprisingly, and less light from below and above the eye. This would allow grazing animals to better detect predators approaching from different directions, the researchers said.
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