thus increasing the quantity of light passing through the retina. In the cat, the tapetum lucidum decreases the absolute threshold for vision, but does not materially change spectral sensitivity. When a tapetum lucidum is present, its location on the eyeball varies with the placement of the eyeball in the head.

Apart from its eyeshine, the tapetum lucidum itself has a color. It is often described as iridescent. In tigers, it is greenish. In ruminants,