It’s common enough on remote islands to just kick back and look at the stars twinkling overhead, but in the Maldives in particular, the stellar light show seems to be between your toes.
Photographer Will Ho’s shots of the luminous blue beaches of Vaadhoo Island in the Maldives went viral back in 2012, but the shimmering phenomenon isn’t unique to that archipelago and, contrary to appearances, it’s not displaced stardust.
There’s a couple of explanations, the most common being phytoplankton: Microscopic organisms that produce their own light through a process of bioluminescence, especially when jostled by waves or tourists’ sandals.
Another explanation, is that the little beings are actually ostracod crustaceans, whose similarly-coloured lights last for longer than phytoplankton, and who experience periodic die-offs in the Maldives.
Whichever it is, it offers visitors a night-time stroll experience that would be hard to match elsewhere.
Natural phenomenon: Glowing blue water washes up on a beach in Vaadhoo, one of the Raa Atoll islands in the Maldives. The result of a chemical reaction called bioluminescence, it occurs when a micro-organism in sea water is disturbed by oxygen
The reaction is similar to the ‘glow’ that fireflies use to attract prey or mates.
Some living things can light up dark places without help from the sun.
While fireflies are the best-known bioluminescent creatures, other species of insect, fungi, bacteria, jellyfish and bony fish can also glow. They employ a chemical reaction to glow at night, caves or most frequently, the black depths of the ocean.
Bioluminescence is scattered within the tree of life — although no flowering plants and few animals with backbones possess this ability — and researchers believe the ability evolved independently many times. [A Glow in the Dark Gallery]
Glow-in-the-dark organisms use variations on a chemical reaction that involves at least three ingredients: an enzyme called luciferase, which helps oxygen bind to an organic molecule (the third ingredient), called luciferin. The high-energy molecule created by the reaction releases energy in the form of light.
For organisms that do it, bioluminescence has many uses, according to the exhibit materials. Fireflies use flash to attract mates and to warn predators of the toxins they contain. Deep-sea anglerfish use a lighted lure to attract prey. The stomach lights on ponyfish evolved as a sort of camouflage to help them blend in with light filtering down from above. Dinoflagellates — the single-celled protists behind red tides — light up when disturbed, perhaps to startle predators or to attract creatures that eat their predators. Click beetles appear to use light to make themselves seem larger. Fungus gnat larvae glow to attract prey to sticky fishing lines that resemble bead necklaces. Vampire squid squirt out clouds of light to confuse predators.
Most bioluminescent organisms, about 80 percent of species, live in the most vast habitat on the planet — the deep sea. In fact, it is estimated that most species below 2,297 feet (700 meters) can produce their own light.
Luciferins, these light-producing molecules, are all good antioxidants, so it is thought that they may have been around as antioxidants, then, over time, they were co-opted for signaling,” Sparks said.
As the oxygen content of the oceans increased, animals moved into deeper waters, out of the reach of harmful ultraviolet radiation. In the deep water, where the antioxidants were no longer needed to repair genetic damage caused by UV radiation, luciferins became the basis for a light-producing system, he said.
Not everything that glows is bioluminescent. Some organisms, such as corals, fluoresce, meaning they absorb light at one wavelength, such as UV radiation, and emit it at another wavelength. Since UV light isn’t visible to the human eye, these creatures can appear to produce their own light.
The exhibit “Creatures of Light: Nature’s Bioluminescence” opens at the American Museum of Natural History on Saturday (March 31) and is scheduled to run until Jan. 6, 2013.
You can follow LiveScience senior writer Wynne Parry on Twitter @Wynne_Parry. Follow LiveScience for the latest in science news and discoveries on Twitter @livescience and on Facebook.
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