Nocturnal animals tend to have proportionally bigger eyes than humans do. They also tend to have pupils that open more widely in low light. So, at the outset, nocturnal eyes gather more light than ...

Living animals illustrate every possible intermediate between the primitive light-sensitive patches ... (Euphilomedes morini), has two compound eyes (brown spot, far right) to avoid predators ...

The TL changes to a deep blue, reflecting less light out of the eye. This change helps reindeer see better in the winter's darkness and spot predators in low light ...

The animal's eyes change from a golden colour to a deep blue as summer fades to winter, helping it to see in dramatically different light levels. The part that changes colour is called the tapetum ...