Why does coral glow

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Castells, L. Nature In shallow waters, they glow a brilliant pink and purple. In deeper waters, corals turn red and green against a dim blue background. The fluorescent pigments absorb damaging wavelengths of light and emit it as pink or purple light, protecting the single-celled organisms called zooxanthellae that live symbiotically inside coral.

Zooxanthellae are photosynthetic and they provide the coral with food in exchange for shelter. In fact, in those dim blue waters, the problem was more likely too little light. Wiedenmann and his colleagues now have a new study , in which they present a novel function for deep water fluorescence. And again, it has to do with the zooxanthellae: Coral may be converting blue light into orange-red light that penetrates deeper into the coral tissue, where photosynthetic zooxanthellae live.

In the past, scientists have suggested that shallow-water corals might be able to migrate or find refuge in deeper, cooler waters. Erin Blakemore is a Boulder, Colorado-based journalist. Learn more at erinblakemore. These glowing corals live deep in the Red Sea.

Several sea pens and corals emit waves of glowing light that travel across their bodies, as do some brittle stars, sea cucumbers, and even comb jellies. The researchers suggest that these waves of glowing light could confuse potential predators or attract larger animals that might eat the animal trying to eat the coral.

Several corals and the flytrap anemone documented in this study released glowing slime, a trait shared by many other deep-sea animals, including comb jellies, medusae jellyfish , midwater worms, and the vampire squid.

The researchers suspect that such slime might stick to the body of a potential predator, once again making it vulnerable to attack from larger animals. Under normal ROV lighting, flytrap anemones look ferocious.

Flytrap anemones may discourage predators by releasing glowing slime when disturbed. The scientists are still trying to understand why some corals evolved to glow blue while others use GFP to make green light instead.

Of the animals examined in this study, the ones that glowed blue lived in shallower water 1, meters , while those that glowed green using GFP lived in relatively deep water 3, meters. This paper shows that many deep-sea corals can produce their own light, and suggests that they inherited this ability from a common ancestor. However scientists are still working out the complex evolutionary history and relationships among corals, as well as the genes involved in making light.

This study shows how important bioluminescence is to many deep-sea animals. It also suggests that activities such as deep-sea mining, which reduce visibility near the seafloor, could affect deep-sea ecosystems in ways we might not expect. The research could also have commercial applications. It sets the stage for genomic and biochemical studies that could reveal the details how the different coral bioluminescent systems work. This, in turn, could help scientists isolate new glowing compounds—like GFP—for use in the life sciences.

But we described other types of luciferase from a variety of species, some of which showed unique behaviors. For example, the luciferase of one sea pen we studied is sensitive to calcium ions, which are involved in nearly every aspect of cellular biology. We also find more evidence that bioluminescence is truly a key means of communication for many marine animals. Bessho-Uehara, M. Francis, and S.