Fluorescent Corals

Many species of coral produce fluorescent pigments that light up in a dazzling display of neon colours when exposed to UV light.

Fluorescence is the phenomenon whereby a substance absorbs electromagnetic radiation (such as light) and emits it at a lower energy level. In this case, the corals’ fluorescent proteins absorb invisible high energy UV light and emits visible light, which has longer wavelengths and lower energy.

Scientists have hypothesised several reasons for fluorescence in corals.

Corals form symbiotic relationships with algae called zooxanthellae, which they house in their polyps. The algae photosynthesise and provide nutrients for the coral. However, the algae are not able to process UV light. Through fluorescence, the corals may be able to turn the UV light into wavelengths that are useful to the algae for photosynthesis, especially in darker environments. 

It has also been suggested that the fluorescence provides protection against UV rays, notably in shallow water. UV rays are mutagenic and are capable of damaging cells in both the coral and symbiotic algae. Fluorescence may be a means to convert UV light into harmless lower energy wavelengths in order to protect both the coral and algal cells.

Studies have shown that corals with higher concentrations of fluorescent proteins are more resistant to bleaching.

Check out more photos of fluorescent corals on flickr

© via Flickr

Reefscape
Tony Shih on Flickr

Reefscape

Tony Shih on Flickr

Gorgonian Forest
Saspotato on Flickr

Gorgonian Forest

Saspotato on Flickr

Bubble Coral Shrimp
Some species of shrimp live exclusively in corals and anemones. As rent, they clean the host of food scraps.
Tony Shih on Flickr

Bubble Coral Shrimp

Some species of shrimp live exclusively in corals and anemones. As rent, they clean the host of food scraps.

Tony Shih on Flickr

A Goby on a Xeno Crab on a Whip Coral
Klaus Stiefel on Flickr

A Goby on a Xeno Crab on a Whip Coral

Klaus Stiefel on Flickr

Coral Bleaching
When under stress, corals cannot supply nutrients to zooxanthellae, the symbiotic algae which gives the coral its colour, and loses them as a result. Mild bleaching can be reversed as zooxanthellae recolonize the coral body.
Klaus Stiefel on Flickr

Coral Bleaching

When under stress, corals cannot supply nutrients to zooxanthellae, the symbiotic algae which gives the coral its colour, and loses them as a result. Mild bleaching can be reversed as zooxanthellae recolonize the coral body.

Klaus Stiefel on Flickr

Reefscape
Tony Shih on Flickr

Reefscape

Tony Shih on Flickr