إلى اخي واستاذي ابو سلطان Pictures: Glowing Blue Waves Explained
Pictures: Glowing Blue Waves Explained- https://images.nationalgeographic.com...152_100x75.jpgSea of Stars
Photograph by Doug Perrine, Alamy
Pinpricks of light on the shore seem to mirror stars above in an undated picture taken on Vaadhoo Island in the Maldives.
The biological light, or bioluminescence, in the waves is the product of marine microbes called phytoplankton—and now scientists think they know how some of these life-forms create their brilliant blue glow.
Various species of phytoplankton are known to bioluminesce, and their lights can be seen in oceans all around the world, said marine biologist and bioluminescence expert Woodland Hastings of Harvard University. (Also see "Glowing Sea Beasts: Photos Shed Light on Bioluminescence.")
"I've been across the Atlantic and Pacific, and I've never seen a spot that wasn't bioluminescent or a night that [bioluminescence] couldn't be seen," Hastings said.
The most common type of marine bioluminescence is generated by phytoplankton known as dinoflagellates. A recent study co-authored by Hastings has for the first time identified a special channel in the dinoflagellate cell membrane that responds to electrical signals—offering a potential mechanism for how the algae create their unique illumination.
—Ker Than
Published March 19, 2012
- https://images.nationalgeographic.com...150_100x75.jpgLights on the Water
Photograph by Mike Blake, Reuters
Bioluminescent phytoplankton light up rolling surf during a so-called red tide event along the coast of Leucadia, California, in September 2011. Red tides—often rusty-hued in daylight—can occur all over the world and are caused by large-scale algae blooms.
Some red tides, like the one shown here, contain phytoplankton that emit bursts of light when agitated.
In the recent study, published last October in the Proceedings of the National Academy of Sciences, the team confirmed the existence of channels in dinoflagellates that allow only protons—positively charged particles—to pass through. (Related: "Proton Smaller Than Thought—May Rewrite Laws of Physics.")
"The newly discovered channel had just the right properties needed to trigger the flash," said study co-author Thomas DeCoursey, an electrophysiologist at Rush University in Chicago. "If you replaced the dinoflagellate channel with the [corresponding cell] channel from humans or mice or snails, it could not do the job."
The study authors propose that, as dinoflagellates float, movement in the surrounding water sends electrical impulses around a proton-filled compartment inside the microorganisms.
The electrical pulses open the voltage-sensitive proton channels, triggering a series of chemical reactions, which ultimately activate a protein called luciferase that produces the neon blue light.
Published March 19, 2012
- https://images.nationalgeographic.com...151_100x75.jpgLanding Strip
Photograph courtesy James R. Evans, U.S. Navy
A sailor stands watch on the back of the aircraft carrier U.S.S. Carl Vinson as bioluminescent microorganisms illuminate the surrounding water.
The glowing blue water is easily visible from the air—something pilots use to their advantage, Harvard's Hastings said.
Aircraft carrier-based jet pilots "often follow the trail of luminescence left in the wake of their ship to find their way back after a night mission," he said. (Related: "As Jet Fuel Prices Soar, a Green Option Nears the Runway.")
Published March 19, 2012
- https://images.nationalgeographic.com...163_100x75.jpgSparkling Sands
Photograph by Russ Taylor
Sand along a beach in the Florida Everglades glows with a soft blue light emitted by countless microscopic phytoplankton washed ashore.
Similar phytoplankton are found in lakes, but they aren't bioluminescent. "That's one of the enigmas about bioluminescence: Why has it never evolved in fresh water?" Hastings said.
(Also see "Large, 'Glamorous' New Glowing Squid Species Found.")
Published March 19, 2012
- https://images.nationalgeographic.com...148_100x75.jpgRed (and Blue) Tide
Photograph by Mike Blake, Reuters
Bioluminescent phytoplankton give the incoming surf an electric blue glow along a beach in Leucadia, California, in September 2011.
Some dinoflagellates can produce toxins that are harmful to fish, humans, and other creatures. Scientists think bioluminescence may also be a form of defense for the life-forms.
Much like a rattlesnake's tail, the light could act as "a signal that alerts a predator that it might be a bad idea to eat this prey," Hastings said. (Also see "Coral Algae Have 'Eyes,' Study Says.")
According to another idea, called the "burglar alarm" theory, bioluminescent phytoplankton use their light to hopefully attract the attention of secondary predators, which might attack any creature trying to consume the marine microbes.
Published March 19, 2012
- https://images.nationalgeographic.com...147_100x75.jpgFrom Sea to Shining Sea
Photograph from Travelart/Alamy
Bioluminescent phytoplankton glitter on the incoming tide along an island beach in the Maldives.
Dinoflagellates—the subjects of the recent study—are single-celled organisms, "but some of them are big enough that you can actually see them with the naked eye," Rush University's DeCoursey said.
(Related: "Giant 'Amoebas' Found in Deepest Place on Earth.")
Published March 19, 2012
- https://images.nationalgeographic.com...149_100x75.jpgLuminous Tendrils
Photograph by Adam Plezer, Your Shot
Glowing phytoplankton create clusters and filaments of light as they wash ashore in an undated photograph taken from the Lakshadweep Islands off India.
Harvard's Hastings, who has spent his life studying marine bioluminescence, encourages people to go out to a beach at night to witness the living light show for themselves. Pictures, he says, can't truly capture the experience.
For instance, photos tend to blur the points of light together, he said. But "it's very much a phenomenon caused by individual cells."
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