Colored scanning electron micrograph (SEM) of a firefly (Photinus pyralis). These winged beetles, also known as lightning bugs, are named for their ability to flash their abdomens. This is achieved using an enzyme (luciferase) to oxidize a chemical in a chamber in the tip of its abdomen. , and is known as bioluminescence. The firefly controls the flashes by regulating the amount of oxygen that enters the chamber. The flashes of light are used to attract mates. Magnification: x10 when printed at 10 centimeters wide.