is light produced by a chemical reaction which originates in an organism. There are a variety of examples of it, but most come from creatures in the ocean. This image comes from this National Geographic website: http://bit.ly/GS1jav
and what you're seeing here is phytoplankton.
I did not take this shot, but I'm sharing it because I want to seek out something like this... Anyone know where this is going on in the world right now?
I'd love to go see it and photograph it. If you start searching and finding other cool photographs, please hashtag them so I can see what you find. #bioluminescence
Here's an old-school website about the phenomena: http://www.lifesci.ucsb.edu/~biolum/