March 23, 2012 - Humans may figuratively glow from within, but many species literally emit a natural glow. Here, we celebrate just some of these flashy organisms, such as these fireflies. Photographer Tsuneaki Hiramatsu used slow–shutter speed photos to produce images like this one of firefly signals.
"These images show a selection of many extraordinary organisms that produce light, in conjunction with the American Museum of Natural History's upcoming Creatures of Light: Nature’s Bioluminescence exhibition," curator John Sparks of the museum’s Department of Ichthyology, told Discovery News.
Bioluminescence refers to organisms that "generate light through a chemical reaction."
Bitter Oyster Mushrooms
It’s a little known fact that some common mushrooms glow in the dark.
These bitter oyster mushrooms (Panellus stipticus) are bioluminescent. They grow on decaying wood in the forests of eastern North America.
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The flickering glow in this photo comes from thousands of live single-celled organisms called dinoflagellates.
The species seen here, Pyrocystis fusiformis, is a spindle-shaped cell about one millimeter long -- just large enough to be seen without a microscope, according to Sparks. Tiny particles in each cell, called scintillons, contain chemicals that mix and make light when the water is shaken or stirred.
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Bloody Bay Wall
This interactive mural captures a slice of life on Bloody Bay Wall, off Little Cayman Island in the Caribbean Sea. In daylight, creatures on this coral wall can be seen in fine detail. To most observers, this scene might look quite normal, but it takes on an eerie glow at night.
Sparks said, "Rare among organisms that live on land, the ability to glow is much more common in the ocean, where up to 90 percent of animals at depths below 700 meters are bioluminescent, including many unknown to science."
Green Fluorescent Protein
The brilliant patches of green here come from a compound known as "green fluorescent protein" emitted from certain corals, fishes and sea anemones. The vivid colors only appear when the animals are illuminated by specific wavelengths of light.
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If a different wavelength of light illuminates the same scene, glowing red hues emerge. Orange is yet another color that some glowing organisms can emit.
"Like the crystal jelly, whose glow led to a revolution in cellular biology, these animals may hold important clues to essential questions regarding signaling mechanisms, sexual selection, and diversification in the deep sea," Sparks said.
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Some scorpions, such as the one seen here, are fluorescent. Certain spiders, insects and minerals glow too. Sparks explained that the luminescent minerals contain fluorescent molecules that glow under ultraviolet light.
Andrew Parker, research leader of the Department of Zoology at London’s Natural History Museum, explained that as soon as certain organisms evolved the ability to see, color, light, fluorescence and more all gained greater importance.
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“Since vision evolved, everything has been fully adapted to the presence of a retina, adapted in terms of their color, shape and behavior,” Parker, author of the related book In the Blink of an Eye, told Discovery News. “Prior to the first highly mobile predator with vision, i.e. one that could have an affect on all other cohabitants, the rules would have been much different, and indeed we know from fossils that animal forms and ecology were much different.”
The female black dragonfish has a luminous lip that may be used to attract prey. The poor victims would then be chomped to death by the fish’s big, sharp teeth. Both males and females also have tiny light-emitting photophores scattered over their bodies, with larger photophores along the side.
Rui Coelho, a shark researcher at the University of Algarve, Portugal, has studied bioluminescent marine animals. He told Discovery News that "photophores may be used to allow individuals to escape from predators or for species recognition, such as during the mating season."
The appropriately named lanternfish conspicuously uses bioluminescence in its ocean habitat. Although virtually all fish are at risk now, due to bycatch threats, pollution and other problems, laternfish account for approximately 65 percent of all deep sea fish, based on ocean trawling counts.
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Danaphos is the name of an oceanic ray-finned fish genus. Its more common name is "bottlelights." It, and so many other species, both on land and in the sea, are under threat now. Sparks shared that "scientists are in a race against time as habitats are increasingly threatened by pollution, overfishing, and global climate change."
You can, however, non-invasively admire Danaphos and the other glowing species at the new AMNH exhibit, which opens March 31 in New York and runs until Jan. 6, 2013.
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