July 1, 2006 For centuries, sailors in the Indian Ocean have told stories of seas glowing with a dim, white light at night. Satellite images have now confirmed the appearance of what seem to be bioluminescent bacteria, right where a ship's crew reported seeing the "milky seas" 11 years ago. Scientists say this rare phenomenon could be a way for the bacteria to attract the attention of fish so they can enter their guts and live there.
ORLANDO, Fla. -- Two scientists believe they've solved a mystery that's defied explanation for more than 400 years. The phenomenon known as milky seas, once thought to be folklore, may be real.
"They were completely surrounded by waters that appeared as a field of snow or clouds in all directions," says marine meteorologist Steve Miller of the Naval Research Laboratory/Marine Meteorology Division in Monterey, Calif.
Miller is quoting the log of the S.S. Lima as it cruised off the coast of Somalia 11 years ago. There are hundreds of such reports since the seventeenth century. In Jules Verne's "20,000 Leagues Under the Sea," crew members talk about "sailing in a sea of milk."
Is it fact or fiction?
"The continuous nature of the light and the, sort of, the milky look of it both kind of indicate that it's coming from something that's really, really small and is producing a continuous glow," bioluminescence expert Steve Haddock, of Monterey Bay Aquarium Research Institute in Moss Landing, Calif., tells DBIS.
The milky seas are caused by bacteria that produce light just like fireflies light up at night, giving a signal.
"All the bacteria that are in that volume will start to glow," Haddock says.
To prove their point, Miller and Haddock searched satellite images to find pictures of the Indian Ocean when the S.S. Lima traveled it. They plotted the ship's course, and there it was on the satellite image...
"It was one of those chill-down-the-spine moments that you hope to get once or twice in your career," Miller tells DBIS.
How many bacteria would it take to light up the seas? Four billion trillion.
Haddock says, "If you were going to cover the surface of the earth with a four-inch layer of sand and then count all the grains of sand in that layer, that's the same number as the number of bacteria in the milky sea."
...An unsolved mystery with a hypothesis that just may explain it. Proving once again, truth is sometimes stranger than fiction.
The milky sea phenomena seem to only last a few days. Miller and Haddock hope to find out about one in time to dispatch a science vessel to study it. The milky seas seem to occur primarily in the Indian Ocean
BACKGROUND: Scientists are now investigating the reason that the ocean sometimes lights up in the dead of night. This glow has mystified sailors for over 400 years. Scientists speculate that the bacterium vibrio harveyi, a cousin of the microbe that causes cholera, is responsible for milky seas. They have recently been able to capture the first satellite images of a "milky sea." Thanks to satellite imagery, scientists can rush out to investigate these glowing patches of seawater that were previously thought to be just folklore.
WHAT IS BIOLUMINESCENCE: Bioluminescence is the ability of a living organism to emit light. In bioluminescence a chemical reaction triggers an electron to jump to a higher level. Then the electron loses energy and falls back to a lower level, emitting the excess energy in the form of a particle of light. No energy is lost as heat, as in other means of light production, so bioluminescence is often called "cold light." The most common color of bioluminescent light produced by marine organisms is blue, which is also the color that penetrates farthest through water. In "milky seas," this light appears white because the rods in the human eye (used for night vision) don't discriminate color.
GLOWING BACTERIA: Dinoflagellates are organisms that cause red tides, flashing waves and the sparkling waves behind boats as they churn through the water, but these organisms must be physically stimulated to produce those brief bright flashes. In contrast, vibrio harveyi will glow with a continuous light on their own, under the right conditions. Those conditions include very high concentrations of the bacterial in order to accumulate enough of the trace chemical that induces this light production. A conservative estimate calls for 40 billion trillion bacteria packed into a space the size of Hawaii. This is equivalent to the number of grains of sand it would take to cover the entire earth with a layer 10 centimeters thick.
The American Society for Microbiology contributed to the information contained in the TV portion of this report.