21 October 2014

Imagine sitting in a kayak in a cluster of mangrove trees in Puerto Rico, the waves gently lapping up against your boat. All around you it is dark; the stars of the night sky provide just enough light to make out the dim shapes of other boats and the curly, tangled branches of the mangroves. You reach your hand alongside the boat and dip it into the dark water. All of a sudden, the water lights up, sparkling with bluish-green light where you’ve put your hand. The sea’s light comes from the water all around you. It’s almost as if you are kayaking over the surface of shimmering Halloween glow-sticks!

This amazing phenomenon is called bioluminescence and it happens all throughout the ocean. I saw it for the first time in Fajardo, Puerto Rico on a night like the one I described above.

How does it work?

The water does not really light up. Instead, there are tiny organisms in the water called dinoflagellates. Bioluminescence is caused by a chemical reaction triggered in the organism by motion in the water. The cells sense pressure changes, so, when you put your hand, a paddle, or anything else (even you, if you are swimming!) in the water, the dinoflagellates light up in response to the movement. The dinoflagellates are in the water all the time, but they only light up at certain times. Scientists have many ideas about why. Sometimes, it might be a defense mechanism, when an organism is in danger. Other times, it might be to attract prey or to communicate.  Dinoflagellates get their energy for bioluminescence through a process that is similar to photosynthesis in plants. They gather other energy during the day as they float on the ocean’s water, soaking up the sun.

Where can I see it?

One of the best places to see this phenomenon is in Puerto Rico. The two largest bio bays in Puerto Rico are Mosquito Bay near Vieques and Las Croabas Lagoon in Fajardo. Both of these bioluminescent bays are sheltered from the open ocean, so they have bioluminescence all year long. There used to be bioluminescent bays in many other places, but pollution and changes in the water have made bio bays like the ones in Puerto Rico very rare.

This phenomenon also can be observed along other ocean shores around the world. It’s called a red tide or algal bloom and it happens from time-to-time, temporarily, when there are large numbers of dinoflagellates in the water. Unlike the bio bays in Puerto Rico, bioluminescence connected with a red tide lasts for just a few days or weeks at a time.

Not All Bioluminescence is the Same

There are also different kinds of bioluminescence and it works differently in different kinds of organisms and creatures. We now know that many creatures in the deep ocean rely on bioluminescence to attract food or to scare away predators.  Jellyfish, squid, fish, and sharks have all been photographed or videoed exhibiting the amazing ability to light up under water. Scientists are learning more about the deep ocean with the help of submarines and robotic exploration. Maybe you remember the father in the book Nim’s Island? He was a scientist searching for bioluminescence in the ocean. Scientists today believe that almost ninety percent of deep-sea creatures in the dark, dark waters of the ocean have some kind of bioluminescence.

Bioluminescence happens on land too. Maybe you have seen a firefly blinking to attract a mate or glowing firefox fungus in the woods. Remember the glowing forest and magical creatures in Avatar? That was a fictional form of bioluminescence. The glow from these organisms—real and imagined—is similar to the dinoflagellates and deep ocean creatures.

Have you been lucky enough to witness bioluminescence in the ocean? Where and when? Share your stories in the comments section.

I Want To Know More About the Science of Bioluminescence!

• “Lights Alive” at the San Diego Natural History Museum:

  • http://www.sdnhm.org/archive/kids/lightsalive/biolum3.html

• “Creatures of Light” at the American Museum of Natural History

  • http://www.amnh.org/exhibitions/current-exhibitions/creatures-of-light

• Scripps Institute of Oceanography:

  • http://explorations.ucsd.edu/for-kids/voyager/2011/voyager-does-bioluminescence-occur-in-just-one-color-or-are-there-different-colors/

I Want To See More Photos!

Flickr Bioluminescence Gallery:

https://www.flickr.com/groups/746474@N25/

Photo Credit for This Post:

In the photo for this post, photographer Ricky Qi captures a pod of dolphins lit up by bioluminescent dinoflagellates near La Jolla, California. Check out the original photo and more at Qi's photo stream here: http://www.flickr.com/photos/rickyqi/6204258162/in/photostream/