Sunday, 25 September 2016

BIOLUMINESCENCE

जैव संदीप्ति
You may have seen the sparkle of fireflies on a summer’s night. The fireflies produce light through a chemical reaction in their glowing abdomens, a process known as bioluminescence.
Bioluminescence is the production and emission of light by a living organism. It is a form of chemiluminescence.

But did you know that seascapes can also glow and glitter.


How it's made?

Bioluminescence occurs through a chemical reaction that produces light energy within an organism's body. For a reaction to occur, a species must contain luciferin, a molecule that, when it reacts with oxygen, produces light. There are different types of luciferin, which vary depending on the animal hosting the reaction. Many organisms also produce the catalyst luciferase, which helps to speed up the reaction.
Animals can closely control when they light up by regulating their chemistry and brain processes depending on their immediate needs, whether a meal or a mate. Some organisms even bundle the luciferin with oxygen in what is called a “photoprotein”—like a pre-packaged bioluminescence bomb—that is ready to light up the moment a certain ion (typically calcium) becomes present. They can even choose the intensity and color of the lights.

Who makes it?

Bioluminescence is found in many marine organisms: bacteria, algae, jellyfish, worms, crustaceans, seastars, fish, and sharks to name just a few. In some cases, animals take in bacteria or other bioluminescent creatures to gain the ability to light up. For example, the Hawaiian bobtail squid has a special light organ that is colonized by bioluminescent bacteria within hours of its birth. But usually the animal itself contains the chemicals necessary for the reaction that produces bioluminescence.

What colour is bioluminescence?

Light travels in waves of different shapes—known as wavelengths—which determine the color of the light. When the waves hit our eyes, they are translated into colors by the brain depending on their wavelength. The wavelengths that our eyes can see are known as the "visible light spectrum," and we can see all the colors on this spectrum as they travel through the air above land. But light travels differently underwater because longer wavelengths can't travel as far. Most of the bioluminescence produced in the ocean is in the form of blue-green light. This is because these colors are shorter wavelengths of light, which can travel through (and thus be seen) in both shallow and deep water. Light traveling from the sun of longer wavelengths—such as red light—doesn't reach the deep sea. This is why many deep sea animals are red: it's effectively the same as being invisible. Moreover, because it's not present, many deep-water animals have lost the ability to see it altogether. However, some animals evolved to emit and see red light, including the dragonfish (Malacosteus). By creating their own red light in the deep sea, they are able to see red-colored prey, as well as communicate and even show prey to other dragonfish, while other unsuspecting animals cannot see their red lights as a warning to flee.

Why animals light up?

Animals can use their light to lure prey towards their mouths, or even to light up the area nearby so that they can see their next meal a bit better. Sometimes the prey being lured can be small plankton, like those attracted to the bioluminescence around the beak of the Stauroteuthis octopus. But the light can also fool larger animals. Whales and squid are attracted to the glowing underside of the cookie-cutter shark, which grabs a bite out of the animals once they are close. The deep-sea anglerfish lures prey straight to its mouth with a dangling bioluminescent barbel, lit by glowing bacteria.

For the animals who bioluminesce, it is a matter of communicating and protecting themselves from being eaten or hurt. But for humans, the beautiful colors and light that are produced by bioluminescence can be works of art.
Bioluminescence can also be used as a tool by researchers to learn more about the ocean and its mysteries.

Source:-
http://ocean.si.edu/bioluminescence
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