Fire salamander (Salamandra salamandra) exhibiting a biofluorescent glow on its ventral side.
Photo Credit: © Bernat Burriel-Carranza, Museu de Ciències Naturals de Barcelona, Spain
Scientific Frontline: Extended "At a Glance" Summary: Biofluorescence in the Fire Salamander
The Core Concept: The fire salamander (Salamandra salamandra) exhibits a previously undetected trait, emitting a bright turquoise-blue biofluorescent glow when exposed to ultraviolet light.
Key Distinction/Mechanism: Unlike bioluminescence (where organisms generate their own light through internal chemical reactions like fireflies), biofluorescence depends entirely on an external light source. Chemical substances in the salamander's skin absorb invisible ultraviolet light and re-emit it into the visible spectrum as vivid green and cyan tones.
Origin/History: Published in May 2026 in Royal Society Open Science by an international team including researchers from the Max Planck Institute and the Museum of Natural Sciences in Barcelona, this discovery revealed a glowing trait that had gone completely unnoticed despite decades of rigorous study on the species.
Major Frameworks/Components:
- Glandular Origin: The fluorescence is highly concentrated on the underside and sides of the body, originating specifically from the skin glands and their secretions, which can maintain a glow for over 24 hours after release.
- Systemic Distribution: The fluorescent compounds are found in the salamander's blood and granular glands, suggesting a complex systemic distribution that is exceptionally rare in amphibians.
- Aposematic Signaling: The fluorescent cyan-green speckles perfectly align with the yellow warning spots and toxic secretions (samandarines), suggesting the glow functions as an advanced nocturnal warning system against predators or a means of intraspecies communication under moonlight.
Branch of Science: Evolutionary Biology, Chemical Ecology, Herpetology, and Zoology.
Future Application: The ongoing chemical characterization of the unknown fluorescent molecule could yield novel biochemical compounds. Furthermore, understanding this optical trait offers new, non-invasive methods for researchers to monitor salamander populations and map nocturnal interactions in dense forest environments.
Why It Matters: This breakthrough dramatically expands our understanding of amphibian biology and visually oriented nocturnal communication. Because the fire salamander is listed as a vulnerable species, deciphering these hidden ecological functions is vital for developing better-informed conservation and habitat-protection strategies.
Ultraviolet-Induced Blue-Green Biofluorescence Reveals a Previously Undetected Trait in a Well-Studied Amphibian
An international research team led by scientists from the Museum of Natural Sciences in Barcelona, the Institute of Evolutionary Biology (IBE), a joint center of the Spanish National Research Council (CSIC) and Pompeu Fabra University (UPF), and the Max Planck Institute for Chemical Ecology in Jena, Germany, has discovered that the fire salamander (Salamandra salamandra) is biofluorescent. Their work, published in Royal Society Open Science, reveals that this iconic species emits turquoise light when exposed to ultraviolet radiation. This phenomenon had gone unnoticed despite decades of study.
The salamander is a widely known animal in Europe, easily identifiable by its unmistakable black and yellow pattern and by the toxic secretions it uses as a defense mechanism. The International Union for Conservation of Nature (IUCN) lists the salamander as “vulnerable” on its Red List of Threatened Species. It is affected by the degradation and fragmentation of its habitats and can be found mainly in humid forests, streams, and mountain areas.
An Amphibian That Glows at Night in the Forest
The study reveals that this biofluorescence is mainly concentrated in the ventral yellow area and on the sides of the body. Specifically, it originates primarily from the skin glands and the secretions they produce, which can maintain their fluorescent capacity for more than 24 hours after being released.
“It is fascinating that such a well-studied species still harbors unknown phenomena like this. It reminds us that even the most familiar organisms can hide secrets that are only revealed when they are observed with new tools,” says Bernat Burriel, a researcher at the Museum of Natural Sciences in Barcelona and first author of the work.
When it receives ultraviolet light—imperceptible to the human eye—chemical substances present in the salamander’s skin transform it and emit it back into the visible spectrum, manifesting a striking coloration in green and cyan tones. This phenomenon, called biofluorescence, differs from bioluminescence because it depends on an external light source. By contrast, bioluminescent organisms, such as fireflies, generate their own light through chemical reactions.
For many years, biofluorescence was considered to be limited to marine environments, with scorpions being a rare exception. However, a series of recent discoveries has revealed that it is also common in terrestrial environments, with reports in several groups of animals, including reptiles, birds, and amphibians.
What Is the Purpose of Biofluorescence, and What Substance Causes It?
The results suggest that biofluorescence may have significant ecological functions. For instance, it may facilitate communication among individuals, influence the selection of a mating partner, or reinforce warning signals against predators.
“Fluorescence meets several criteria that suggest a communicative function. It could help salamanders detect each other in nocturnal or particularly dense environments, or act as an additional defense signal,” says Martin Kaltenpoth, director of the Department of Insect Symbiosis at the Max Planck Institute for Chemical Ecology and a coauthor of the study. In addition, the fact that it is found in toxic secretions also opens up new hypotheses about its role in interactions with other species.
The specific role of fluorescence in fire salamanders is still speculative. However, visually oriented animals with high sensitivity could perceive this cyan-green fluorescence at very low intensities. Humans, on the other hand, can only see this fluorescence with the aid of a UV lamp. In a forest at night, the only light that reaches the ground where salamanders live comes from the stars and the moon. Interestingly, full moonlight contains more UV and violet wavelengths than daylight, which has a relatively homogeneous distribution of wavelengths. Therefore, salamanders may increase their visibility to each other by adding cyan-green speckles to their yellow skin.
The salamander’s natural fluorescence may also be part of an aposematic signaling strategy. This occurs when animals exhibit visible warning colors to alert predators that they are toxic. The link between warning coloration and toxic compounds was first established in salamanders more than a century ago with the discovery of samandarines, a group of highly toxic steroidal alkaloids originating from cholesterol precursors.
“The presence of this fluorescent compound was surprising because salamander skin secretions have been studied chemically for decades, and we were unaware of any published reports on fluorescence,” says Andrés Brunetti, a researcher at the Max Planck Institute for Chemical Ecology and co-first author of the study.
“We still don’t know what the compound responsible for this fluorescence is, but everything indicates that it is a molecule unknown until now in this species. Identifying it will be key to understanding its origin and function,” adds Salvador Carranza, a researcher at the IBE (CSIC-UPF) and a coauthor of the study. The researchers are currently in the process of chemically characterizing candidate compounds.
Implications for Research and Conservation
The discovery expands knowledge about amphibian biology and highlights the importance of studying organisms from new perspectives. It can also have implications for conservation, as a better understanding of the mechanisms of communication and behavior can help protect vulnerable species.
This study, which also included researchers from the Institute of Subtropical Biology and the Catalan Society of Herpetology, is part of a pioneering amphibian conservation project in Catalonia funded by the Barcelona Zoo Foundation.
Published in journal: Royal Society Open Science
Authors: Bernat Burriel-Carranza, Andrés E. Brunetti, Margarita Skamnelou, Jorge Escudero, Maria Estarellas, Sergi Tulloch, Gabriel Riaño, Xavier Rivera, Maria-Dolors Piulachs, Tobias Engl, Benjamin Weiss, Martin Kaltenpoth, and Salvador Carranza
Source/Credit: Max-Planck-Gesellschaft
Edited by: Scientific Frontline
Reference Number: ebio052726_01