MORE ON THIS: It is easy to see the beauty of coral reefs when snorkeling or diving during the day, but have you ever seen the colors of coral at night?
Coral reefs are known to put on a light show known as bio-fluorescence.  A family of proteins provides this fluorescence by absorbing one color and emitting another.  Each protein provides a different color; the most common is the green fluorescent protein known as GFP.  When the wavelengths of color are absorbed then re-emitted, some of the energy is lost.  This changes the wavelength, which determines the color.

Species of coral known to give off this fluorescence are found in Hawai‘i and can be seen on night dives with special dive lights.  If you’re interested in seeing this phenomenon, you can contact your local dive shop to ask about night diving to see fluorescent coral or, if you’d like to stay dry, you can visit the Maui Ocean Center which has some of this coral on exhibit.


It is unknown why fluorescence occurs, but there are speculations from scientists.  Some believe that it acts as a sunscreen for the coral.  Researchers also have proposed that the fluorescence creates light to allow algae to grow in deeper water; algae is the major food source of most corals.
Research is focusing on coral fluorescence for several reasons.  The first reason is due to the fragile state of coral reefs in our climate-changing world.  Some studies suggest that the intensity of the fluorescence can be a sign that the coral is under stress and may indicate that the coral is about to bleach.
Medical research is also greatly benefiting from coral fluorescence research.  The same proteins the corals use to fluoresce are being used to help monitor biological processes within diseases to further understand how they work. This is done by using the fluorescence as a marker so scientists can watch cells divide or viruses spread.
FURTHER READING:

  1. Roach, John. 2005. “Glowing Coral Proteins Aid Medical Research.” National Geographic. http://news.nationalgeographic.com/news/2005/01/0112_050112_coralproteins.html
  2. Roth,  Melissa S., Fran, Tung-Yung, Deheyen, Dimitri D. 2013. “Life History Changes in Coral Fluorescence and the Effects of Light Intensity on Larval Physiology and Settelement in Seriatopora hystrix.” Plos One. http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0059476
  3. University of California – San Diego. 2013. “Fluorescent light revealed as gauge of coral health: Mysterious glow of light found to correlate with coral stress prior to bleaching.” Science Daily. www.sciencedaily.com/releases/2013/03/130312092918.htm.

Written by Sarah Mousel