Biofluorescence in Larval Salamanders

Abstract:

Biofluorescence has been widely documented in marine life, but only a few studies have looked for this trait in terrestrial vertebrates. Indeed, biofluorescence was found to be a widespread trait among many adult amphibians in 2020. In particular, many adult salamanders have been documented to biofluoresce green in response to blue light. How this biofluorescence in response to blue light changes throughout development in salamander species, however, is unknown. For our study, we observed how patterns of biofluorescence in response to blue light changed through larval and metamorph development in spotted salamanders (Ambystoma maculatum) and red-spotted newts (Notophthalmus viridescens viridescens). To do this, we captured different larval stages and recently metamorphosed spotted salamanders and red-spotted newts around Behrend’s campus. The side and ventral surface of larvae and metamorphs were photographed under normal lighting and in the presence of blue excitation light with a longpass filter (500 nm) to document which tissues biofluoresced in response to blue light at each stage. We found that larval salamanders of both species exhibited decreased levels of biofluorescence throughout development. In red-spotted newt metamorphs, three different patterns of biofluorescence were observed which varied in brightness. We also documented, for the first time, that newt metamorphs biofluoresced orange in response to blue light. Research on biofluorescence in terrestrial vertebrates is limited, so our study is a novel contribution that uses ontogeny to provide insight into the function of amphibian biofluorescence. Given that most amphibian species are threatened with extinction, we must improve our understanding of amphibians to understand better what steps we can take to protect them in the future.