Category Science

Fireflies are winged beetles with light-producing organs called photic organs located in the lower part of their abdomen Bioluminescence in fireflies serves several purposes – to attract mates, to lure prey and in larvae, the light serves as a warning to predators not to eat them because they contain distasteful toxic chemicals. Firefly light is usually to each species. Some fireflies are capable of synchronising their light emission in a phenomenon known as simultaneous bioluminescence.

This phenomenon has been observed only in a few places such as the Great Smoky Mountains National Park in Tennessee, the U.S, and in the mangrove forests of Southeast Asia.

Fireflies appear to light up for a variety of reasons. The larvae produce short glows and are primarily active at night, even though many species are subterranean or semi-aquatic. Fireflies produce defensive steroids in their bodies that make them unpalatable to predators. Larvae use their glows as warning displays to communicate their distastefulness. As adults, many fireflies have flash patterns unique to their species and use them to identify other members of their species as well as to discriminate between members of the opposite sex. Several studies have shown that female fireflies choose mates depending upon specific male flash pattern characteristics. Higher male flash rates, as well as increased flash intensity, have been shown to be more attractive to females in two different firefly species.

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Comb Jellies are fascinating creatures that have special features- rows of ‘comb’ with hair-like structures called cilia, evenly spaced around their bodies. The organism uses these cilia like oars to swim in the water. Comb jellies are known for generating dramatic rainbows of colours along the comb-rows while swimming. But that’s not bioluminescence- it occurs when light is scattered in different directions by the movement of cilia. But comb jellies also secrete luminescent ink that serves to distract predators providing time for them to escape.

Until 2015 scientists believed that comb jellies removed their waste via their “mouth,” or what was believed to be the one hole in their body plan. A new study showed that comb jellies in fact release indigestible particles through pores on the rear end of the animal. This discovery adds another piece to the evolutionary puzzle of when animals evolved to have anuses.

Many comb jellies have a single pair of tentacles (often each tentacle is branched, giving the illusion of many tentacles) that they use like fishing lines to catch prey. They are armed with sticky cells (colloblasts) and unlike jellyfish, the tentacles of comb jellies don’t sting.

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More than 70 species of mushrooms are bioluminescent. Some of them light up only at night. As the temperature drops when the sun sets, the fungi begin to glow. Scientists believe fungi such as mushrooms, glow in order to attract insects. Insects are drawn to the mushrooms, which crawl around them. They pick up the spores of the fungi and help spread them. Fungal spores are microscopic biological particles that allow fungi to reproduce- what seeds are for plants, spores are for fungi. The light of fungi ranges from blue to green and yellow, depending on the species.

Scientists went foraging for the glow-in-the-dark mushrooms in Brazil and Vietnam. Back in the lab, reports Becker, they crushed the mushrooms to make a slurry filled with luciferins. Then they isolated the luciferin and studied it, capturing its chemical structure and experimenting with its ability to fuel those flourescent colors.

Not only does the team now know that the mushrooms are fueled by their own kind of luciferin, but they also figured out that the enzyme that combines with the chemical to trigger light could be what they call “promiscuous.”

That means that the enzyme might be able to interact with different luciferins—and produce even more shades of that pretty glow. And that suggests that when it comes to these magical mushrooms, there’s even more to discover.

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Sunlight does not penetrate 200 ft below the ocean’s surface, so the deep sea is essentially a cold, dark place. But if you dive underwater and go deep down, you may witness a blue-green glow here or a ghostly flicker there. And if you are lucky or a ghostly flicker there. And if you are lucky enough, you may witness lightshows of red, green, and blue. Where are these lights coming from? From marine organisms. This phenomenon of emitting light due to a chemical reaction within a living organism is called bioluminescence.

Shining stars

Though marine bioluminescent organisms live throughout the water column, from the surface to the seafloor and from near the coast to the open ocean, they are extremely common in the deep sea. As many as 90% of all the organisms in the deep sea are bioluminescent. Its the norm there, say scientists. Some of the bioluminescent marine organisms include fish, jellyfish, bacteria, algae, marine worms, crustaceans (shrimp, lobster, krill etc.), sharks and cephalopad (octopus, squid, cuttelfish). In fish alone, there are about 1,500 known species that emit light.

Thought rare, bioluminescence be witnessed among a few terrestrial organisms as well. They include firefiles, land snails, glow worms and some types of fungi. Some forms of bioluminescnence are brighter or exist only at night.

Chemical reaction

How is the light produced? The light is produced by a chemical reaction involving light-emitting molecule luciferin and light-emitting enzyme luciderase found in the organisms. When luciferase interacts with luciferin in the presence of oxygen, light is produced.

But not all bioluminescent reaction involve luciferase. Some involve a chemical called photoprotein instead of luciferase.

Some creatures produce their own light while others such as squid foster a symbiotic relationship with certain bacteria that live on the organism and emit light to help the host. (The host organisms provide these bacteria a safe home and sufficient nutrition. In exchange, the hosts use light produced by the bacteria for camouflage, prey or mate attraction.)

Colour choice

Most marine organisms emit light in the blue-green part of the visible light spectrum. These colours are more easily visible in the deep ocean. Land organisms also exhibit blue-green bioluminescence, but there are those that glow yellow such as fireflies.

A few organisms can glow in more than one colour. The head of the railroad worm(a larvae of a beetle species) glows red while its body glows green. The bioluminescent colour is a result of the arrangement of luciferin molecules and the type of the luciferase enzyme.

What the purpose?

Bioluminescent organisms often light up in response to an attack or a disturbance such as touch, waves or the passing of a boat (e.g: dinoflagellate); some use it to hunt prey (anglerfish has a fleshy growth on its head, which, when lit up, looks like a fatty, juicy worm. The fish uses it to attract prey); to find mate (the female of Bolitaena pygmaea), a deep-sea octopus species, lights up around the mouth to attract mate) and to communicate (scientists think the lanternshark uses bioluminescence to communicate to other members of its species). Some use bioluminescence as a defence tactic to surprise or confuse a predator (many types of jellyfish and squids) or to camouflage (hatchet fish and many shark species produce light to match their background).

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