text: It actually depends on the animal!\n\nThe eye consists of Rods and Cones.  Rods handle detail.  They are the most sensitive. That is why cats can see intricate detail, such as the predicted direction of the jumping of a mouse due to muscle twitches, than to if the mouse is white, black or orange.  Cones handle colors.\n\nSee the source for better definition\n\nOn a side note... visible light is just a small part of the electomagnetic spectrum.  Some animals can see infrared, but are blind to purples, while others cant see red, but see ultraviolet light!