Light on Earth

In this preview of the new BBC film David Attenborough's Light on Earth, the legendary narrator explains Mother Nature's bioluminescence. 

Luminous beings, creatures with their own internal light, enchant and astonish us. Anyone who has seen a firefly or a glow-worm cannot help but fall under their spell. The sea at night sparkles as millions of luminous plankton reveal the shapes of dolphins in a truly magical light show. But why do animals produce living light?

(via Laughing Squid)