A recent study published in Royal Society Open Science has revealed that fluorescence, or the ability to “glow” under ultraviolet (UV) light, is extremely common among mammals. The researchers examined various mammal species to determine the prevalence of fluorescence and to confirm that it was indeed fluorescence and not another phenomenon. They also investigated whether the fluorescence observed in museum specimens was natural and not caused by preservation methods.
Fluorescence occurs when certain chemicals in an organism’s scales, skin, or fur absorb UV light and emit visible light. While fluorescence has been reported in birds, reptiles, amphibians, fish, corals, molluscs, and arthropods, it has been less frequently described in mammals. However, recent studies have provided examples of fluorescence in mammals such as rodents and platypuses.
To investigate the prevalence of fluorescence in mammals, the researchers obtained preserved and frozen specimens from museums and wildlife parks. They started with the platypus and found a faint fluorescent glow when photographing preserved and frozen specimens under UV light. To confirm that this was indeed fluorescence, they used a technique called fluorescence spectroscopy to analyze the emission spectrum of the glow.
The researchers repeated this process for other mammals and found clear evidence of fluorescence in species such as koalas, Tasmanian devils, echidnas, wombats, bandicoots, bilbies, and cats. Both fresh-frozen and chemically treated museum specimens exhibited fluorescence, indicating that it was a real biological phenomenon and not caused by preservation chemicals.
Using specimens from the Western Australian Museum’s collection, the researchers identified 125 fluorescent species of mammals, representing all known orders. They also found that white and light-colored fur tended to be fluorescent, while dark pigmentation prevented fluorescence. Additionally, they discovered that nocturnal mammals were more likely to exhibit fluorescence compared to aquatic species.
Based on their findings, the researchers suggest that fluorescence is very common in mammals and may be the default status of hair unless heavily pigmented. While fluorescence may not have a biological function, it could enhance the visibility of pale-colored parts of animals that serve as visual signals, especially in low light conditions.
