Salamanders and Other Amphibians are Aglow with Biofluorescence
Authors: Jennifer Y. Lamb and Matthew P. Davis
Journal: Scientific Reports
Published: February 27, 2020
We are all aware of biofluorescence in the animal kingdom - mostly in invertebrates and aquatic fish. This is done when high energy wavelength of light, such as blue or ultra-violet, is absorbed by the body and is remitted as lower energy wavelengths of red, green, or lighter blues. Keep in mind that this is different from bioluminescence where light is emitted via a biological chemical reaction. But did you know that amphibians are perfectly capable of emitting light as well? This natural phenomenon is observed in the orders of Apoda, Anura, and Caudata. In the Caudata family, it is unknown if fluorescence occurs in the families Hypnobiidae and Rhyacotritonidae. The researchers of this article sought to confirm this and to speculate on the functional benefits biofluorecence provides for amphibians.
To test this, 8 families of salamanders, 5 families of frogs, and 1 family of caecilians were obtained or observed from the field, pet stores, and aquariums. The specimens were then examined for the response they gave when exposed to blue (440-460 nm) and ultra-violet (360-380 nm) light. It was found that all species that were observed are biofluorescent. This includes all life stages, such as aquatic larvae. When exposed to the wavelengths described above, amphibians emitted back green to yellow light. Patterns of this is highly variable depending on pigmented stripes, spots, or mottling. However, pigmentation does not correlate to biofluorescence as amphibians lacking markings also fluoresce. Compare the patterns shown in the image below. Fortunately, it includes species we have already studied!
Anatomy also played a large part on which areas which were fluorescent or relatively brighter. It was observed that in some species, the ventral was brighter than the dorsal or there was specific prominence on bony digits, cloaca, or cutaneous mucus secretions.
The evidence from this study reveals that biofluorecence is not restricted within salamanders, frogs, and caecilians. This sheds some light on the evolutionary history of amphibians, as this trait is likely to be a synapomorphy of a recent common ancestor related to all individuals of this class.
In addition, it adds to the visual communication aspect of amphibians. Amphibian retinas have red rods that is highly sensitive to green light, and with the addition of green rods (which are sensitive to blue light), contribute to color discrimination and biofluorescent identification of the same species. It may also have a role in sexual selection and mate choice. As mentioned before, the highlighted cloacae may have an additive function in visual communication and behavior for the courtship of salamanders.
With this study, the researchers recommend further investigation of biofluorecence in amphibians, especially frogs and caecilians. There also needs to be additional research of the structural mechanisms involved in amphibian biofluorecence and should go further into what specific compound, protein, and/or metabolite is responsible for this trait.
Source:
https://www.nature.com/articles/s41598-020-59528-9#Sec3
2 comments:
I never knew that these species could be bioluminescent! When I think of bioluminescence I tend to think of deep-sea creatures so this was something new for me.
Very cool! Thanks for sharing!
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