Illuminating the Early Life of Salamanders: Exploring Biofluorescence During Development

Biofluorescence in tetrapods has rapidly become a captivating area of study. This phenomenon was previously identified to be widespread across amphibian diversity, but few studies have investigated biofluorescence in early life history stages. The aquatic environments inhabited by the early developmental stages of biphasic amphibians are different from those of terrestrial, post-metamorphic individuals. This could translate to differences in the presence and function of biofluorescence. In our study, we explored the biofluorescence of developing embryos and larvae of three species of mole salamander (Ambystoma) and one species of newt (Notophthalmus) in response to different excitation wavelengths. We discovered that the colors, intensity, and locations of maximal fluorescence varied ontogenically and by species. Although fluorescence occurred in response to both blue and green light, it was more prevalent and intense under blue excitation. Under blue excitation, we observed predominantly green fluorescence, but orange-red wavelengths were emitted in some taxa and developmental stages. We discuss intrinsic and external mechanisms that may be contributing to fluorescence in the eggs, embryos, and larvae of salamanders. We also use previously published criteria to generate hypotheses about the potential ecological significance of fluorescence in the aquatic life history stages of salamanders.