In late September, marine biologist David Gruber revealed the world’s first recording of a reptile displaying bioflourescent behavior. The hawksbill sea turtle that Gruber observed in the waters around the Solomon Islands (off the coast of Australia) displayed green and red colors.
Some reports have confused Gruber’s discovery, referring to the hawksbill’s glow as being bioluminescent, rather than bioflourescent. What’s the difference?
Bioflourescence requires an external light source that is absorbed by the animal before re-emitting the light. Bioluminescence requires no external light source, the entire process happens within the animals.
Gruber summed up the difference simply by defining bioflourescence this way: “Turn off the light source, and there’s no fluorescence.” If an animal can display colored light without living near sunlight, it is bioluminescent, not biofluorescent.
Most bioluminescent animals live at depths that visible sunlight never reaches and only the blue spectrum of light exists while bioflourescent animals live in regions where they can absorb sunlight, which they later use.
Many animals in both the water (corals, jellyfish, sharks to name a few) and on the land or in the air (butterflies, parrots) have been known to possess bioflourescence, but this is the first time that any reptile has displayed the ability even though some experts have studied the hawksbill sea turtle for years.
Animals display bioflourescent and/or bioluminescent behaviors for a variety of reasons including communication, defense and predation.