The mysteries of why and how many animals in the deep sea emit light, known as bioluminescence, continue to puzzle scientists studying the evolution of this natural glow.

©  2010 National Geographic, video courtesy Edith Widder

There is a lot that isn’t known about life in the deep sea.

And biologist Edith Widder says if you dive deep, “turn out the lights” and you’ll see even more that still needs to be explored and studied

While it’s rare for land-dwelling animals to do so, Widder estimates that up to 90-percent of animals living in the open ocean make light, known as bioluminescence. And it makes for some impressive displays for the human eye.

Jellyfish…… pelagic worms…. A black dragon fish… are just a few creatures