I have lived in the San Francisco Bay Area for over 30 years, and there are only three things that I miss from my birthplace in the Southern U.S. -- dramatic electrical storms, warm humid summer nights and last but not least, fireflies. But last weekend I got a real good dose of our local offering of bioluminescence -- dinoflagellates. Dino what?
On Saturday evening I went kayaking in Tomales Bay in west Marin. It was perfect -- the temperature mild, the wind light and the tides just right. We paddled west toward the setting sun. Western gulls and double crested cormorants flew from all directions into their tree roosts on Hog Island. As darkness descended and the stars appeared, we began to see it. Shimmering lights as our paddles stroked the water; thousands of bioluminescent organisms glowing in the disturbed sea. Wow!
Bioluminescence is simply the creation of light by living organisms. The basic chemical reaction involves a compound called luciferin, an enzyme called lucerifase and the addition of that great fiery compound common on our planet -- oxygen. When this chemical reaction occurs, light is emitted without the accompaniment of heat, a rare event in nature.
We were watching dinoflagellates called Noctiluca, which literally means "night light." These one-celled organisms have nearly a worldwide distribution but are more common in warm tropical waters. In Tomales Bay they begin blooming when the sea warms up a bit in late summer and early fall.
So why do they light up like that? They don't even have eyes, so have no idea how cool they look. Well, there are some predaceous crustaceans called copepods that just love to eat Noctiluca. Fish that feed on these copepods are attracted by the light emitted by the disturbed dinoflagellates and then head on over and eat the dinoflagellates major predator. Bioluminescence at work!