That strange glow you sometimes see for a brief moment when you’re standing on the beach at night and staring toward the crashing waves might not be your eyes playing tricks on you after all. It also might not be the moon’s reflection or the flicker of an underwater flashlight or any other explanation you may have come up with. That strange glimmer in the water may be real, and it may have a natural explanation.
I’ve been curious about the phenomena of bioluminescence – the chemical production of light by living organisms – for many years. In the terrestrial environment, fireflies do it, as do some beetles and a few mushrooms. But in the ocean, numerous creatures can produce light
under various circumstances – to lure prey, to attract a mate, or
to frighten predators away, among other reasons. In Monterey Bay, California,
scientists recently calculated that three-quarters of all marine species are
|Bioluminescent plankton in the Maldives (Doug Perrine)|
In the waters of the Ocean State, bioluminescence is most often seen in the late summer and fall when some types of microscopic plants called dinoflagellates multiply in large numbers. If there are enough of them, these dinoflagellates will glow when disturbed, like when waves crash around them. If you are out boating on the water at night under the right conditions, they also might glow when you jump in the water or start your engine.
Some grape-sized jellyfish called ctenophores and a few kinds of tiny crustaceans also use bioluminescence in local waters.
According to Jim Sullivan, a Providence native and former marine scientist at the University of Rhode Island who is now a professor at Florida Atlantic University, bioluminescence typically occurs when a particular protein and enzyme combine in the body to release photons of light. Creatures typically keep the protein and enzyme separated inside specialized structures in their cells until they are triggered to come together.
“There’s a biochemical control for turning it on and off,” he told me. “In the case of the dinoflagellates, it typically happens when another organism goes to eat them, but they flash as soon as they are touched, and that flash startles the predator, which lets goes of it and runs away.”
The flash of light might also attract a larger predator to come and eat the smaller predator.
A great many questions still remain about bioluminescence, yet few scientists are studying the subject. The U.S. Navy funded most of the research into bioluminescence in the 1980s and 1990s when it believed that modern satellites might be able to detect the movement of submarines by the trail of bioluminescence in their wakes. Sullivan conducted studies of bioluminescence off Iceland back then when Russian submarines were known to frequent the waters in the area.
Today, the research funding has dried up, but it’s still a fascinating phenomenon to observe.
My only experience with bioluminescence in the ocean was during a midnight walk out to Napatree Point in Westerly several years ago when I was volunteering to monitor breeding horseshoe crabs. During a break in the action, I stared toward the crashing waves and saw what appeared to be a brief blue-green flash of light. It reminded me of a distant flash of lightning or the green flash some say is visible at the moment the sun sets.
Or maybe it was just my eyes playing tricks on me.
This article first appeared in the Newport Daily News on October 21, 2017.