A hidden world of light: Biofluorescence in fish
A new paper is out in PLOS ONE about biofluorescence in fish. This is the first jaw-dropper for me of 2014. The bottom line is this: an awful lot of first are actually fluorescent if you hit them with the correct spectrum of light (usually far blue to UV), we just can’t see it isolated from all the other colors and patterns without a little help from technology.
Here is the original paper: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0083259 (it is #openaccess like all things in PLOS).
Light filters out long wavelengths (like red) quite readily, so even rather shallow reef floors get mostly blue light and other energetic wavelengths. When these wavelengths hit fish, some of it is re-emitted as red, green, or yellow light. Properly photographed (as seen below – figure from the paper) we can see the amazing glow of rays, sharks, and ray-finned fish. Note that these animals are not closely related, so biofluorescence is widespread in an evolutionary sense.
But here is the part that really blows my mind. The authors have determined that one reason so many fish might glow is because the entire reef is actually glowing. Let that sink in for a moment. Coral reefs are actually an explosion of crazy fluorescent color, and fish are blending in by glowing along with it.
Excerpt from the paper:
“In addition, we present evidence that some fish lineages might be utilizing fluorescence as a means of camouflage in specific marine environments (Fig. 5; Videos S1, S2). Red and far-red biofluorescence is a ubiquitous feature of photosynthetic organisms due to the properties of chlorophyll and other photosynthetic pigment complexes. The photosynthetic apparatus associated with chlorophyll fluoresces red and provides a background of biofluorescence in areas of algal growth”
The authors note algal growth, but corals (which house photosynthetic organisms) are also highly fluorescent. If you want to know more about biofluorescence corals, check this out: https://plus.google.com/+DanielStoupin/posts/B4xY1sjp5Xv
Next time you are in ocean, just imagine the explosion of extra color that is present all around you.