Human's can't see infrared light, but many animals can. Goldfish, some butterflies and certain species of snake can see infrared radiation, which humans can only feel as a heat medium. Bees, birds, lizards and some insects can also see ultraviolet (UV) light, which is at the other end of the light spectrum.
More facts about infrared and ultraviolet light:
Humans can see infrared with the use of night vision equipment, or with thermographic devices. Infrared radiation is used in things such as remote controls, personal digital assistants (PDAs) and certain types of telescopes. Art historians can use infrared radiation to see layers of paintings that have been painted over, such as a portrait of a woman by Vincent van Gogh beneath his painting Grasgond.
Some butterflies use ultraviolet light to communicate. White cabbage butterflies, for instance, use a UV light reflection system in their mating rituals.
Penguins' eyesight is mostly tuned to greens, blues and purples, but they also can see light in the ultraviolet range, which is thought to help them hunt in the water.