Researchers at James Cook University (JCU) have been investigating why some Australian mammals glow under ultraviolet (UV) light.
Led by researcher Linda Reinhold, the team aimed to understand the chemistry behind this strange phenomenon, which is known as photoluminescence.
Their study, recently published in PLOS One, sheds light on the mysterious glow seen in many mammals, including rats, bandicoots, possums, bats, and tree-kangaroos.
Photoluminescence occurs when certain molecules in animal fur absorb UV light and re-emit it as visible light, creating a glowing effect.
Reinhold explained that the team wanted to identify the specific molecules—called luminophores—responsible for this glow, particularly the striking pink color seen in some species.
To investigate, the researchers collected fur samples from roadkill and examined them using a technique called high-performance liquid chromatography.
This allowed them to analyze the chemical composition of the fur and identify the specific molecules involved in photoluminescence.
The study focused on two species of bandicoots—the Australian northern long-nosed bandicoot and the northern brown bandicoot—both of which glow vividly under UV light. The researchers also compared these bandicoots to other photoluminescent mammals, including the northern quoll, the coppery brushtail possum, Lumholtz’s tree-kangaroo, the pale field rat, and even the platypus.
The team discovered that the bright pink glow seen in the fur of bandicoots, quolls, and possums is due to derivatives of the chemical compound porphyrin. Porphyrins are naturally occurring molecules that are also found in human blood and can fluoresce under UV light. Additionally, the researchers identified metabolites of tryptophan—an amino acid known for its role in mood regulation in humans—as contributors to the glow.
Interestingly, while analyzing the coppery brushtail possum, the team found something unexpected. Although the possum’s fur does not glow under UV light, it displays a strong purple color in normal white light. This unusual coloration was traced back to the molecule Indigo, which is famously used as a dye for fabrics. This surprising discovery has raised new questions about the unusual fur colors of other Australian mammals, such as the purple-necked rock-wallaby.
Reinhold noted that this study is the first of its kind to explore the photoluminescent chemistry of Australian mammal fur since 1971. The findings not only solve a long-standing mystery but also open doors for further research into the chemical make-up of fur and its evolutionary purpose.
The study has sparked excitement among scientists, as it could lead to new insights into how and why these animals evolved to glow under UV light—a trait that remains largely unexplained.
