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Fire salamanders (Salamandra salamandra) are amphibians commonly found in the forests of Europe. They are easily recognized by their black bodies with bright yellow markings, which serve as warning colors to predators. These salamanders also produce poisonous substances through special glands in their skin to protect themselves from danger. However, researchers have discovered another surprising feature: fire salamanders can produce a blue-green glow when exposed to ultraviolet (UV) light. This phenomenon is called biofluorescence, which occurs when certain molecules absorb light and release it at a different, usually longer, wavelength. Unlike bioluminescent animals, such as fireflies, fluorescent animals do not produce this light through their own chemical reactions. Instead, they need an outside light source to make the glow visible. A study published in Royal Society Open Science revealed that this hidden fluorescence is closely associated with the salamanders’ skin glands and secretions (Burriel-Carranza et al., 2026).

To understand this unusual feature, researchers examined fire salamanders using ultraviolet lights, specialized cameras, and microscopes. They discovered that the glow appeared mainly along the animals’ sides and undersides, particularly in areas associated with skin glands. Further examination revealed strong fluorescence in the outer skin and glands that produce chemical secretions. Interestingly, the salamanders’ secretions could continue glowing for more than 24 hours after leaving their bodies. Scientists also observed fluorescent signals in blood vessels near some glands, suggesting that the substances involved might be transported through the bloodstream. Fire salamanders use toxic skin secretions as a defense against predators, but researchers have not established whether fluorescence contributes to this protection. The discovery raises an interesting biological question: Could the glowing chemicals serve another purpose, or is fluorescence simply an unexpected property of substances already present in the salamanders’ bodies? (Burriel-Carranza et al., 2026).

Fire salamanders are not the only amphibians capable of fluorescence. Earlier research by Lamb and Davis (2020) found that biofluorescence occurs across many amphibian groups, including salamanders, frogs, and caecilians. The researchers observed that different amphibian species produce different glowing patterns, often associated with their skin colors and body structures. Fluorescence has also been documented in other animals, including certain fish and scorpions. However, the biological purpose of this phenomenon is still not fully understood. In fire salamanders, scientists suggest that fluorescence might help individuals recognize one another, locate potential mates, or strengthen their warning colors against predators. However, detecting fluorescence under laboratory lighting does not necessarily mean that animals can see it in nature. To determine whether the glow is useful for communication or defense, scientists would need to study the salamanders’ vision, natural lighting conditions, and behavioral responses to fluorescent signals (Burriel-Carranza et al., 2026; Lamb & Davis, 2020).

The discovery highlights an important difference between finding a biological feature and understanding why it exists. Although fire salamanders clearly display fluorescence under certain lighting conditions, scientists still do not know the exact chemical compounds responsible for the glow or whether this feature provides an evolutionary advantage. It is possible that fluorescence plays a role in survival or communication, but it could also be a byproduct of the salamanders’ skin chemistry without a specific biological function. Further studies could compare fluorescent compounds among amphibian species, examine how predators respond to glowing patterns, and investigate whether fluorescence influences animal behavior in natural environments. Such research could improve our understanding of amphibian physiology, chemical defenses, and evolution. Fire salamanders also face conservation threats, including habitat loss and disease, making continued research into their biology particularly valuable. Ultimately, this discovery reminds us that even familiar animals may possess hidden characteristics that science has yet to explain (Burriel-Carranza et al., 2026; Lamb & Davis, 2020).

References

Burriel-Carranza, B., Brunetti, A. E., Skamnelou, M., Escudero, J., Estarellas, M., Tulloch, S., Riaño, G., Rivera, X., Piulachs, M.-D., Engl, T., Weiss, B., Kaltenpoth, M., & Carranza, S. (2026). Glandular biofluorescence in fire salamanders (Salamandra salamandra): First evidence and ecological implications. Royal Society Open Science, 13(5), 251991. https://doi.org/10.1098/rsos.251991

Lamb, J. Y., & Davis, M. P. (2020). Salamanders and other amphibians are aglow with biofluorescence. Scientific Reports, 10, Article 2821. https://doi.org/10.1038/s41598-020-59528-9

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