Imagine standing on the deck of a ship out in the open ocean at night, in wonder at the twinkling stars. In the inky black water below you may also notice blinking, flashing lights, but it is not a reflection of the stars above. These bright displays are made by marine organisms via bioluminescence, a biological reaction that releases light. Researchers have found that as many as 3 out of every 4 species in the open ocean are capable of bioluminescence. It turns out that bioluminescence is a crucial communication tool for the majority of marine organisms, big or small.