Editor's note: These photographs originally appeared on WetPixel Full Frame and have been reposted with permission.

Underwater photographer Alex Tyrell started playing with fluorescent photography equipment back in 2010, and he's never looked back. Unlike bioluminescence (think those glowing blue algal blooms), which is the result of chemical reactions within an organism's body, fluorescence occurs because of the way organisms absorb and emit different wavelengths of light. "What this means is that some marine creatures will 'glow' when the right type of light is shined on them," Tyrell explains. "The right type of light in this instance, is a special blue-filtered light. This, when teamed up with a yellow filter, will make a reef look like downtown London in the middle of December, as corals and anemones shine like festive lights on a dark winter’s evening!"

The exact reason behind this evolutionary marvel remains largely unknown and is still being studied. The most common explanations focus on algae, which might use fluorescence to block out harmful rays on the surface, or to photosynthesise at low light levels in deep water. But with the growing number of known invertebrate (and now fish) families that 'glow', unravelling this mystery could take some time. 

For Tyrell, understanding why animals fluoresce isn't important. Returning to his favourite dive sites and giving them 'the fluoro treatment' renews his love for diving and underwater photography. And it's not hard to see why! 

Fimbriated moray (Gymnothorax fimbriatus). Image: Alex Tyrrell
Striped triplefin (Helcogramma striata). Image: Alex Tyrrell
Star flower coral polyps (Astreopora myriophthalma). Image: Alex Tyrrell
Indian phidiana nudibranchs (Phidiana indica). Image: Alex Tyrrell
Corallimorph (Corallimorphus sp.) Image: Alex Tyrrell
Lisas mantis shrimp (Lysiosquillina lisa). Image: Alex Tyrrell
Boomerang coral (Polyphyllia talpina). Image: Alex Tyrrell
Golden mantis shrimp (Lysiosquilloides mapia). Image: Alex Tyrrell
Green forest staghorn coral (Acropora longicyathus). Image: Alex Tyrrell
Spawning magnificent sea anemone (Heteractis magnifica). Image: Alex Tyrrell
Anemone hermit crab (Dardanus pedunculatus). Image: Alex Tyrrell

For more amazing photos, check out Tyrell's blog here!

Florescence Coral 2015 03 11

Top header image: Alex Tyrrell