The scientists found an ancient light-sensitive gene appears to act as the trigger for the mass spawning of corals across about 132,000 square miles of Australia's Great Barrier Reef shortly after each full moon.

Scientists at the Australia's Center of Excellence for Coral Reef Studies said the genes, known as a cryptochromes, occur in corals, insects, fish and mammals -- including humans -- and are primitive light-sensing pigment mechanisms predating the evolution of eyes.

The researchers, led by University of Queensland scientist Oren Levy, found the Cry2 gene is apparently stimulated by the faint blue light of the full moon.

"This is the key to one of the central mysteries of coral reefs," said University of Queensland Professor Ove Hoegh-Guldberg, in whose laboratory the genes were discovered. "We have always wondered how corals without eyes can detect moonlight and get the precise hour of the right couple of days each year to spawn."

The research that included scientists from Bar-Ilan and Tel-Aviv universities in Israel appears in the journal Science.