Dim those lights, baby!

http://www.sciencedaily.com/releases/2007/10/071019093814.htm

An ancient light-sensitive gene has been isolated by researchers from the ARC Centre of Excellence for Coral Reef Studies (CoECRS) that appears to act as a trigger for the annual mass spawning of corals across a third of a million square kilometres of Australia’s Great Barrier Reef, shortly after a full moon.

The genes, known as a cryptochromes, occur in corals, insects, fish and mammals - including humans - and are primitive light-sensing pigment mechanisms which predate the evolution of eyes