Catching dogfish shark (Squalus acanthias) off the coast of Taiwan lead scientist on the new findings. Palm-sized pygmy shark turned out to help scientists understand the origin of shark species fluoresce.
Indeed, a number of shark species that live in the deep sea are known to emit light (bioluminescence). They have a special organ in the body-side, which can fluoresce.
A recent study demonstrated the ability of pygmy shark sea shark glow in controlling the evolution of the ancestors originated from the shallow sea of sharks. Pygmy shark is a shark species that live in shallow marine habitats.
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| A smalleye pygmy shark (top) and a lantern shark, shown glowing (bottom). (Picture from: http://news.nationalgeographic.com/) |
"Bioluminescence remains the most mysterious thing in the biology of sharks," said Julien Claes from the Catholic University of Louvain in Belgium, who led the study. The findings are published in the latest issue of the journal Experimental Biology.
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| The smalleye pygmy shark is one of the world's tiniest sharks, reaching no longer than 8.7 inches. Its light-emitting organs called photophores cause cause the shark to glow. (Picture from: http://www.theepochtimes.com/) |
According to Claes, there are currently more than 10 percent of shark species are capable of emitting light. Scientists call this light as a "counter-illumination" in the mission of camouflage. Because, without that light, prey that are under it to easily see the body of a shark that looks like a silhouette because of exposure to sunlight from the sky.
Previous research shows sharks use their skills lantern, glowing, to communicate. Named lantern shark because this shark glow like a lamp in the traditional Chinese society.
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| Watch your power glowin'. By secreting hormones into their bloodstream, smalleye pygmy sharks are able to open their small, light-producing organs (blue dots, inset), creating an unearthly glow. (Picture fro: http://news.sciencemag.org/) |
By producing the hormone prolactin, sharks can show bursts of blue light. The light they use to communicate with each other in the dark water that minimal visual cues.
Shark measuring 22 centimeters are found in marine waters Taiwan is one of the smallest species of shark. In the evening, like the pygmy shark to swim at a depth of about 200 meters and continued to move down to a depth of 2.000 meters in the daytime.
In his analysis, Claes found significant differences between pygmy sharks and their larger cousins, one lantern sharks. "The hormone prolactin, which triggers the lantern-light on the real sharks react adversely to the pygmy shark, which is lethal luminescence," he said.
From these findings, Claes assumes that the control of light on the pygmy shark is more ancient than the other types of sharks. This gives a clue as to the ability to evolve on the sharks. "Control of luminescence in some shark species may have evolved from mechanisms of camouflage in shallow-water sharks," said Claes told BBC Nature.
He said the shallow sea shark species are more vulnerable to become victims of predators who are on it. But as a defense mechanism, this type of shark scales can vary the colors to blend with the environment. By producing certain hormones, they can trigger a color scale becomes darker or brighter. This is the basis of deep-sea shark species to control luminescence, "he said.
For both types of shark, the pygmy small and lantern-eyed, light-emitting organ is able to glow constantly. But with the ability to change the color scale becomes darker or brighter, these sharks can effectively turn on or turn off the light fluoresce organs on their bodies.
The results of this study is very important, Claes said, because it provides clues about the evolutionary path of the soft tissue of sharks very rarely leaving a trace fossil. *** [BBC NATURE | MAHARDIKA SATRIA HADI | KORAN TEMPO 3867]
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