Researchers have been attempting to unravel the mystery behind the various pupil forms in the animal kingdom. It seems that eyes may carry clues to reveal which is the hunter and which is the hunted. According to researchers, the geometry of an animal’s pupil indicates a great deal about its place in the pecking order and how high it sits on the food chain.
A team of scientists from the universities of Durham and Berkeley have long investigated animal’s pupils and concluded that there is an undisputable connection between the shape of an animal’s pupil and its hunting habits.
Martin Banks, optometry professor at Berkeley and lead study author explains that animal species that have come to be active during the day and the night (such as domestic cats), slit pupils help to ensure that they are not blinded by daylight but can also see in dim lighting.
Grazing animals, on the other hand, display other particularities. It seems that it is so important to maintain its eyes on the ground that, upon dropping its head, the animal’s pupils rotate as much as 50 degrees to ensure that it remains horizontal.
The team of researchers examined the pupils of 214 terrestrial animals. The examined vertebrates ranged from cats and dogs to Australian snakes, hyenas, grazing animals, rhinoceroses and tapirs. What the scientists hoped to discover was a connection between the shape of the animals’ pupils and their ecological niche.
While humans can only reduce their pupil’s size 15-fold, domestic cats can do so 135-fold while the gecko can reduce its pupil’s gaze 300 fold.
Animals (including humans) that “walk tall” have round eyes and pupils. The majority of hunters and ambush predators (44 out of 65) exhibited vertical pupils and particular shoulder heights (under 16.5 inches), suggesting that such anatomic particularities help them pounce by taking advantage of the difference between the clear focus on the soon-to-be-prey and its out-of-focus surroundings.
Grazing animals, on the other hand, displayed other particularities that allowed them to spot approaching predators. The fact that their pupils rotated in order to remain horizontal ensured that they have a panoramic view, with minimal blind spots.
“They have to see well enough out of the corner of their eye to run quickly and jump over things,” Banks explained.
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