A firefly's light seems rare and magical. Yet there are many living things that blink, glow, flash, and glitter. The deep-sea anglerfish lures prey with a glowing "lure." Cave-dwelling glowworms catch insects with their glimmering tails. Bioluminescent organisms range from sharks to mushrooms. They emit light from different body parts, in an array of colors, and for a variety of purposes. They may glow to attract mates, hunt, or defend themselves.

Image credits: main image, firefly, © Jeff J. Daly/Alamy; mushrooms, © Cassius V. Stevani; deep-sea anglerfish, courtesy of Edith Widder/HBOI; .