Following the accidental discovery by scientists in the United States that platypuses glow under UV light, further tests by Australian scientists show other mammals and marsupials also glow.
Biofluorescence has long been known to occur in some insects and sea creatures, but it was unknown that it occurred in other Australian mammals until earlier this month, when scientists at the Western Australian Museum rushed to check their specimen drawers to factcheck the US report.
The findings have Australian scientists working together to confirm the findings of biofluorescence in these animals, and to start looking for a reason that it may occur.
Paula Anich is a North America squirrel researcher from the Center for Science and the Environment, Northland College in the USA, and co-author of the paper about biofluorescent platypuses that was published in the journal Mammalia.
“It’s hard to resist a platypus,” Dr Anich said.
She was alerted to a pink glow that squirrels exude under UV light by a colleague.
Dr Anich then decided to check some of the other specimens she had to hand.
“We pulled the monotreme [egg-laying mammals like platypuses] drawer and the platypuses fluoresced, and it was amazing,” she told ABC Radio Hobart.
It was also reported by Linda Reinhold, a zoologist and amateur mycologist, in the Autumn/Winter 2020 edition of the Queensland Mycologist that a roadkill specimen of platypus in Queensland was seen to glow under UV light.
More glow in the dark surprises
Palaeontologist and curator of Mammalogy at the Western Australian Museum, Kenny Travouillon, heard about the article and borrowed a UV light from that the arachnology department of the museum.
“We borrowed it and turned off the lights in the collection and looked around for what was glowing and not glowing,” Dr Travouillon said.
“The first one we checked was the platypus obviously.
“We shone the light, and they were also glowing, it confirmed the research.”
Then they turned their light on other specimens in their collection.
“We tried on marsupial moles and wombats,” Dr Travouillon said.
“We did on the carnivorous marsupials and they did not glow at all.
“It probably makes sense, because if their prey can see UV light, they would not be able to hide from them.”
Why do they glow?
Sarah Munks is an adjunct senior researcher with the School of Natural Sciences at the University of Tasmania and an expert in platypuses.
Given that the sample size of three platypus that had been preserved in a drawer in the Northern Hemisphere for decades is not enough for scientists to confirm that glowing fur is endemic to platypuses, she was initially sceptical.
“You mean all these years we have been farting around with ordinary spotlights and we should have been using UV?” Dr Munks said.
“When I first read it, I thought ‘mmm, they were just sad-looking museum specimens’.
“A colleague suggested that they could be covered in urine.”
Benefits to glowing in the dark
Dr Anich hoped the release of the paper would get on the radar of Australian platypus experts.
“I think they are the scientists and wildlife biologists best placed to figure it out,” she said.
“It is possible that it is actually taking the ultraviolet light that is more prevalent at dusk and dawn, making it kind of disappear so that any predators that are keying in on ultraviolet light can’t see the platypus because it is kind of cloaking itself.”
Dr Munks was cautious.
“Their sample size was tiny – and I always like to put in a plug for more research,” she said.
“Is this just a way they can find each other? I don’t think so, platypuses have so many other ways of finding their way around.
“All the work done on other species suggests that it is an ancient form of camouflage.
“It could just be one of these ancestral traits, like humans have remnant tails.
Dr Travouillon suggests that “the benefit is probably so they can see their species from a distance, and they can approach them because they know that it is safe to go towards that animal.”
New collaborations and concern for funding
“It’s incredible seeing it zipping around the researchers,” said Dr Munks, referring to the journal article.
Dr Travouillon posted photos on Twitter of the other animals they tested under UV light, including an echidna, wombats, and bilbies.
“As soon as we posted the pictures, I got contacted from a researcher at Curtin University who works on forensic light and they are interested to do more research,” he said.
“He came with some of his equipment last week and we tested it on some of the specimens and it shows that it is not just UV light but some other lights too.
“We will look at various marsupials to see if there is a pattern with nocturnal mammals, a lot more research coming in the future,” Dr Travouillon said.
“If it’s quirky and interesting like that it will always get people’s attention.”