NIGHT STALKER

Most cats hunt at night and their eyes are much better adapted for seeing in dim light than ours.

The Bigger They Are

One reason for the cat's excellent night vision is that its eyes have very large pupils. Large pupils let more light in to the retina. The bigger the pupils are, the larger the lenses must be. Relative to their size, cats have larger lenses than we do. And cats that are more nocturnal, such as the lynx, have relatively larger lenses than more diurnal species, such as the puma.

The pupil acts as a window into the eye, opening and shutting to control the amount of light that enters. In dim light, the pupil opens in order to let in more light. In bright light, the pupil closes to protect the retina.

When it's dark, a cat's pupils can open much wider than ours and let in more light.

Compare the pupil size of the human, the puma and the lynx.

How do you explain the fact that the human pupil appears larger than the puma's and the puma's seems larger than that of the lynx?


Although the lynx actually has the largest pupil, he was photographed in the brightest light, so his pupil has closed as much as possible to protect his retina. The human was photographed in relatively dim light so her pupil appears large.

In the Eyes of the Beholder

Domestic Cats and most small wild cats have pupils that are nearly round when open wide, but shrink to vertical slits in bright light. All the larger cats, and a few small species, have round pupils that shrink to tiny dots in bright light, like those of humans.

Open Wide

Watch what happens to the pupil as the amount of light increases. Slide the bar to increase the amount of light.

Produced by the Natural History Museum of Los Angeles County.
© Natural History Museum of Los Angeles County Foundation

This page was made possible by a grant from Friskies PetCare Company and the National Science Foundation.

All photographic images contained within these web pages ARE COPYRIGHTED and may not be reproduced, or utilized in any manner, without the express written consent the owner.

Photograph of human, lynx and puma eye models by Jim Angus, © Natural History Museum of Los Angeles County Foundation

Photograph of human eye by Jim Angus, © Natural History Museum of Los Angeles County Foundation

Photographs of puma and lynx eyes from SunSITE Japan Multimedia Collection.

Sketches of cat pupils by Dawn Schiller, © Natural History Museum of Los Angeles County Foundation

Quicktime movie by Jim Angus, © Natural History Museum of Los Angeles County Foundation

Page design by Jim Angus