How does having a non-circular pupil affect the way an animal sees?
In: Biology
The iris shape affects the degree of focus similar to a radar antenna’s shape.
Air Traffic Control radar uses a [wide antenna](https://www.bing.com/images/search?q=ATC+Radar+Antenna&FORM=RESTAB) which generates a vertical fan shaped beam. Anything in a exact direction but at whatever altitude can be detected. The Vertical resolution shows the exact direction. The Horizontal (altitude) direction isn’t as important.
A Height Finding radar uses the opposite – a [tall, narrow antenna](https://www.bing.com/images/search?q=height%20finding%20radar&qs=WebSearch&form=QBIR&sp=1&pq=height%20finding&sc=8-14&cvid=E54A1D8F7AD54648BC7C7BC327A48D81). The fan beam sweeps up and down to detect the exact altitude of the target, which is somewhere in that direction.
A circular antenna generates a narrow cone beam, like in weather and aircraft missile tracking – it gives the exact vertical and horizontal position.
The Predator’s vertical slit eye will have higher resolution vertically, to better resolve the exact elevation of a target before leaping. The Prey’s horizontal slit eye will have higher resolution horizontally to detect the direction of a threat in the grass / bush / tree / sky to run away from.
They’re all trade offs to detect things. Note that the predator’s vertical slit tends to go round (better vertical and horizontal) when it prepares for an attack.
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