Why do coral glow?

[One Reefing Boi]

I understand why they glow in the sense of the Zooxanthellae algae, but why are the colors so bright and vivid. Is there a defense reason like poison dart frogs with bright colors to stave off predators? Is it to attract prey like bioluminescent fish in the deep?
Just curious

 

[xxkenny90xx]

Following

 

[CircleCityBill]

The glow is due to phenomenon called fluorescence. Shorter wavelength radiation (violet, blue, UV light) is absorbed and longer wavelength radiation (eg, orange light) is emitted. Short wavelength radiation (eg, UV) is more likely to cause biochemical damage. The fluorescent proteins in shallow water coral are essentially acting as a sunscreen. Deep water coral are likely using fluorescent proteins as part of the photosynthetic apparatus. Article

 

[justmee]

They're alien creatures...

 

[mattdg]

So you'll want to keep taking care of them. LOL!

 

[Timfish]

The answers to your question ate very complex and scientists are far from understanding the complete picture. They have identified four main purposes for the flourescing protiens corals make though. As mentioned above, two are photo protection and photo enhancement. Another is neutralizing the free radicals caused by photosynthesis. A fourth is a function of the corals immune system to neutralize pathogens or parasites.

 

[Backreefing]

Basically low mn light ( deep blue ) is
Reflected back at higher nm wavelengths .we can’t see deep blue so we’ll but the light coral reflects we can see well . So they glow ( to us ) .

 

[Timfish]

Yes, some of the flourescing proteins made by corals use ultraviolet light but many have excitation wavelengths in the green, yellow and red bands. For more info read Dana Riddle's articles or do a web search using the phrase "Dana Riddle Stokes Shift".

 

[vetteguy53081]

Pigments and response to light and uv

 

[GMM08]

I understand why they glow in the sense of the Zooxanthellae algae, but why are the colors so bright and vivid. Is there a defense reason like poison dart frogs with bright colors to stave off predators? Is it to attract prey like bioluminescent fish in the deep?
Just curious

It's to make them more attractive to reef enthusiasts so that we'll buy them and display them. LOL...just kidding of course, but a great question. I've often wonder this myself. Maybe it's a combination of everything you stated, plus dumb luck, like eye color in humans. ;-)