Why are cats eyes different from humans?

Answer 1

There are two basic differences. The first is in the shape of the iris; the human iris is circular when contracted, while the cat's iris is the characteristic vertical slit when nearly fully closed. The second difference is that the cat's eye has a reflective surface behind the retina. This membrane, the tapetum, reflects light back through the retina a second time, basically giving the vision cells a second chance to see it, and thus making them more sensitive. A side effect of this tapetum is that light reflects back out of the cat's eyes if it is looking at a light source, which can make the cat's eyes seem to glow.

Nobody knows why the iris shape is different, but while a pinhole can make an entire image sharper, a slit will cause an image to be sharper only in the direction perpendicular to the slit, so in bright sunlight, a cat will be able to resolve motion left and right much better than up and down. This may assist the cat in hunting at ground level during daylight hours. The tapetum is quite clearly an adaptation for hunting at low light levels, a benefit to the cat who is, in the wild, nocturnal.

Answer 2

because we are awsome