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Why do cats eyes contract to vertical slit? |
| Reducing the pupils to slits, rather
then tiny circles, gives cat more control over the precisely how much
light enters their eye. For an animal with eyes sensitive enough to see
the very dim light it is important not to be dazzled by bright sun light,
and the narrowing of the pupils to tight slits gives a greater and more
accurate ability to cut down the light in put. The reason why cats have
vertical rather then horizontal ones is that they can use the closing of
the lids to reduce the light input even further. With these two slits -
the vertical one of the pupil and the horizontal one on the eyelids -
working at right angles to one another, the feline eye has the possibility
of making the most delicate adjustment of any animal.
Confirmation of the fact that it is the nocturnal sensitivity of the cat's eyes that is linked with the contraction of the pupils to slits, is found in the observation that lions, which are daytime killers, have eyes that contract, like ours, to circular pinpricks. |