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Re: Elongated Pupils



>     What are the advantages and disadvantages of slitted pupils (like at
>least some crocodilians have) and rounded pupils, like most birds  have?

Slitted pupils allow the eye to take in light more effectively, which allows
the animal to be active at times in the day when light levels are low, lik
at dusk.

I'm not completely certain of the physics behind it, but I think that it has
to do with how light reacts when forced to go through a small space.  As we
all know, light acts like any other wave, being diffracted when it travels
through a confined area.  The resulting diffraction pattern winds up with a
fairly bright central region (the central maximum), with less-bright areas
off to each side (if anyone made a pin-hole camera when they were young,
the concept is the same).  The central maximum for a slit is far brighter
than the maximum for a circle, so an eye that has a slotted pupil will be
able to detect objects even when light levels are minimal.

Rob

***
"They have a basic medical training."
        -MPATHG