Improved animal identification using light-reactive ink. An embodiment comprises: causing a pattern of holes to be formed in a portion of a body of an animal and introducing light-reactive ink into the holes, thereby forming an identifying mark in the portion as a tattoo, the ink being reactive to ultraviolet light such that the identifying mark becomes viewable in response to introduction of ultraviolet light. Introducing an ultraviolet light source in a vicinity of the portion of the body causes the identifying mark to luminesce and thus be visible by a human. The light-reactive ink may contain fluorescent or phosphorescent dye. The portion of the body may be an inner ear of the animal. A color of the ink may substantially match a color of the inner ear of the animal and upon introduction of the ultraviolet light, may have a color different from the color of the inner ear.
