Once a year, billions of bioluminescent firefly squid rush up to the surface in Toyama Bay, Japan to lay eggs. Commercial fisherman and hungry seagulls take advantage of the event, working tirelessly to haul in as many squid as they can catch while the cephalopods are away from their home in the depths of the ocean. Bioluminescence is caused by a chemical reaction, but the exact purpose of the light-producing mechanism remains a mystery.