How does the science work ?

If you've ever wanted to use the term 'Quantum Leap' at a party and actually know what you're talking about here's your chance...


Fluorescence is caused by electrons jumping between orbitas in an atom. Or more accurately, when the electron snaps back to its orignal comfortable orbit.  


When exposed to UV light, fluorescent proteins have electrons that respond to UV exposure by sending the electron further out into a higher energy orbital shell. They cannot exist in this state for long and almost immediately release the extra energy in the form of a photon and a little heat.  

That's it -- a quantum of energy gets released after exposure to a High Energy UV strike.  And we see it one photon at a time !


To make this transformation happen we fluorodivers use intense lights emitting in UV or Blue range (often called 'near-uv"). This torch light is the Excitation Source and it's a very bright blue !  This power overcomes the scene so to bring out the subtler fluorescent emissions we use a yellow Barrier Lens to remove the extra blue.


These are important concepts in fluorodiving:  An Excitation Source creates the fluorescence, then a Barrier Filter removes the extra energy from the scene. If one was doing photography one would put the Exciter on the Strobe and the Barrier over the camera lens.


These excitation sources can be created two ways:  LED's can be chosen in the specific wavelength you wish to explore or you can choose a high-intensity light source and filter out all the extra light you don't need.


I prefer the second way.  LED lights nowadays are particularly bright with a good portion of their light emissions in the Blue/UV end of the spectrum.  As well LED's are so energy efficient it's not difficult to drop up to 95% of the original white through a filtering process. There will be plenty of Blue UV left.  


Most of all -- filtered light sets allow choosing of wavelengths for your torch to aallow exploration into new return colors or increasing the desired effects.


Consider the following two spectral analyses :







This chart shows very strong emission in the UV spectrum. This light would be suitable for initiating strong fluorescence in the proteins but mostly green due to the narrow spectrum.  As well there seems quite a bit of leakage from the Red spectrum that might effect photography.  


This filter shows strong response throughout the target spectrum with little waste.  A filter like this might show more colors besides green.











Choosing the right filter type is important for your area and preferences. Fortunately companies offering filtered torch-kits have done the work for you and will include at least two filters for you to experience the full breadth of the Fluorodiving experience.  Soon more filter choices / matched barrier lenses will become available.  


So the excitement and discoveries will continue. Fluorodiving has a very bright future !

Why do things fluoresce ?

This is a topic of active scientific debate. Nobody really knows for sure. Researchers believe the reason corals fluorescence falls under two categories:  


Protection:  Coral pigments may change damaging UV light into a frequency that's less damaging to their algae, a color-changing sunscreen that turns UV into green. This idea is interesting since fluorescent corals are in more common in shallows, and less so under dark overhangs even at a shallow depth.


Photosynthesis:  There is evidence some corals survive at far greater depths than physics would allow useful light to penetrate. The entire phenomenon of coral fluorescence was only seriously investigated after deep divers witnessed red corals at a depth far beyond red penetration. Only shorter UV wavelengths can penetrate to this depth and there is a possibility the fluorescent proteins change UV light into a more desirable light for algae growth.  

Many other animals besides coral polyps fluoresce for some reason. Some researchers believe this is used for mate attracting or threat displays. I'm not convinced. I believe they are using it to hunt.


My thoughts about why marine animals fluoresce...


Bio Attractant:  Here in Thailand moray eels glow bright lemon yellow illuminating their nook brightly; crabs fluoresce such bright orange they are visible through sand as they wait for prey; sole sport pink spots with glowing rings around their eyes to attract fish, scorpionfish also have glowing eye rings.


The list goes on and the evidence is clear these fish are using fluorescence to hunt. Why not the corals as well ?  Coral polyps are mellow farmers in the day but turn into very effective predators of plankton at night.


Mushroom coral with tentacles extended at night.  I have a video link on this page that shows this mushroom nearly catching a copepod, escaping only because it had a shell.

Large numerous polyps extending from corals normally smooth in the daytime.
































Anemone glowing brightly.  I have a video link on this page showing this anemone catching a juvenile squid.  At first attracted to my bright light, it turned away from the intensity to swim directly into this anemone, perhaps a hundred body lengths away.


Very interesting as well is the Anemone Fishes tendency to try and eat the polyp once it's caught ! I've seen this behavior many times and the anemone fights back by clasping the catch very aggressively.  This is quite clear in the video at low center. Clearly successful hunting using fluorescence also helps feed host fishes.

I firmly believe these corals and other creatures are using this fluorescence as a feed attractant like bioluminescent organisms do in the dark ocean depths. But where would they get the UV light at night ?


Every evening if you watch closely there is a magical time at both sunset and sunrise when there is very little light in the sky, but there is enough light to see.  Blue light. Fluorescence Inducing Light twice a day (to witness this yourself visit the science section). As well many days per year the moon shines very brightly from directly overhead in the tropics, adding considerable bluish light to the shallow corals.


I propose animals use fluorescence to take advantage of short but regular fluorescent periods to augment their total feeding budget, if not largely fill it.  What do you think ?  The research is so new you as a fluorodiver can actually discover your own clues to this scientific mystery !  

What is Fluorodiving ?

Fluorodiving is the use underwater lights of a special wavelength that excite fluorescent proteins in coral and other sea creatures to emit light.


This is not to be confused with Bioluminescence, a chemical reaction independent of any outside light source which happens inside the organs of a creature.  Most popular among divers are the Copepods that erupt like stars at any disturbance, also interesting are the bioluminescent signals and lures of deep ocean creatures.


Luminescence is also a chemical effect, however it relies on an external light source that is stored and released slowly over time.  A classic example is the glowing dial on your pressure gauge.


Fluorescence itself is not limited to animal pigments. Items like fluorescent lights in your home emit light when the phosphor coating inside is stimulated, although in this case not by a light source.


Many things fluoresce from peanut butter to flowers -- to scorpions.  Even humans have fluoro-reactive proteins and the lighting equipment we use is very much like what you see used in Crime Scene Investigation adapted for underwater use.