We knew the platypus were amazing. Now we know they shine too

The platypus is one of the strangest creatures on the planet in many ways. Although mammals, these native Australians lay eggs and sport poisonous spines on their hind legs. They also have beaver-like tails and duck-like beaks, the latter of which they use to detect prey while hunting at night with their eyes closed.

Now scientists have found another odd trait to add to the list: fluorescent fur.

In a recent study published in the journal Mammalia, scientists have discovered that when illuminated by ultraviolet (UV) light – a spectrum of light not visible to human eyes – platypus skins give off a blue-green glow.

“I was a little flabbergasted to [see] the platypus is biofluorescent ”, explains lead author of the study, Paula Anich, especially since it is already“ such a unique animal ”.

The discovery expands scientific knowledge about biofluorescence, which researchers find more prevalent throughout the animal kingdom than previously thought.

“This adds another observation that many animals are biofluorescent, and it raises questions about what, if any, this might mean for the species,” says David Gruber, a National Geographic explorer and researcher who studies the fluorescence in sea creatures and who was not. t involved in the paper.

Biofluorescence is the phenomenon whereby a substance, like fur, absorbs light at one wavelength and emits it at a different wavelength. Common biofluorescent hues include green, red, orange, and blue.

In recent years, scientists have discovered that several types of sea turtle, mushroom, and flying squirrel shells are biofluorescent. Although the reasons are unknown, the hypotheses include camouflage or communication between individuals of the same species.

In 2019, Anich – a mammalogist at Northland College in Ashland, Wisconsin – and her colleagues discovered that flying squirrels fluoresce under UV light, emitting a pink glow from the fur on their bellies. (Learn more about fluorescent flying squirrels.)

These studies led the team to the Field Museum in Chicago, where researchers illuminated preserved squirrel skins with UV lamps. Out of curiosity, they did the same with a platypus specimen stored there – and saw the glow.

Shortly before Anich’s study was published, another research article reported the discovery that a platypus freshly killed on an Australian road glowed under a black light, a lamp that radiates UV rays.

This validates Anich’s discovery and shows that living platypuses, not just long-dead ones, are almost certainly fluorescent, says Gilad Bino, a platypus expert at the University of New South Wales in Sydney, Australia.

“The platypus never ceases to amaze me,” Bino said of the new journal, with which he was not involved.

It’s still not clear why platypuses glow.

Since the animals are nocturnal and keep their eyes closed when swimming, it seems unlikely that they play a significant role in communicating with other platypus, Anich says.

This can help them avoid certain predators that can see UV light; absorbing UV and emitting blue-green light could serve as a form of camouflage, Anich says.

Bino agrees that this is plausible. Many animals, including most birds, can see UV. Native platypus predators include large fish such as Murray cod, birds of prey, and dingoes.

It’s also possible that the trait has no real function – that it is just an ancestral trait that the platypus has retained in addition to its other primitive characteristics, such as spawning.

Anich and Bino say they hope to study a live platypus to confirm the discovery of biofluorescence and possibly learn more about the function of the trait.

“Based on these results,” Bino says, “you can be sure that I will receive a UV projector when I am next in the field.”