Bioluminescence for sexual selection
Fireflies contain the so-called Luciferin, and combined with oxygen enable them to produce light. It is thought that light in adult beetles was originally used for similar warning purposes, but evolved for use in mate selection. Now fireflies are a classic example of an organism that uses bioluminescence for sexual selection. They have evolved a variety of ways to communicate with mates in courtships. From steady glows, flashing, as well as the use of chemical signals unrelated to photic systems.