Species with vertical slits in pupils are more likely to ambush predators.
"For species that are active during the day and at night, such as domestic cats, slit pupils help them to see the dynamic range around them in dim light without being blinded by the midday sun," said Martin Banks, a professor of optometry at the University of California, Berkeley, the lead author of the study.
Gecko's pupil
The vertical seams of domestic cats and geckos have experienced changes of pupil dilation and contraction of 135 and 300 times respectively, while the round pupil of human beings can only change of 15 times. In contrast, species with horizontally elongated pupils are more likely to be herbivorous food species, and their eyes are on both sides of their heads. The round pupil is associated with "active robbers" or animals chasing prey.
For an ambush predator with a vertical slit pupil, the author emphasizes the importance of accurately measuring the distance that an animal can pounce on its prey. The researchers identified three lines to measure the distance: binocular difference, motion parallax and blur. Binocular difference and blur are usually related to vertically elongated pupils and eyes facing forward. The researchers say that a vertical slit pupil will maximize these two clues.
Binocular difference and blur are usually related to vertically elongated pupils and eyes facing forward.
However, the vertical pupils are not evenly distributed among ambush predators. William sprague, a postdoctoral researcher at Banks Laboratory, said: "One of the surprising things we noticed was that slit pupils were related to carnivores near the ground." "So domestic cats have vertical seams, while larger cats, such as tigers and lions, don't. Their pupils are round, just like humans and dogs. " Sprague added. Vertical pupils seem to maximize the ability of small animals to estimate the distance of prey. The study was published in the journal Science Progress.