After checking with the museum’s staff, the team went down to the basement, found the platypus cabinet, and flipped on their special lights. “And sure enough,” Dr. Olson said. They were eventually able to examine three platypuses: a male and a female at the Field Museum, and another male from the University of Nebraska State Museum. All gave off the same cool glow.
So did a road-killed platypus, discovered by a blacklight-wielding mycologist in northeast Australia this summer. Despite the sad circumstances of the finding, “we were elated to know that it was verified in a wild specimen,” Dr. Olson said.
So why would a platypus fluoresce?
“We really don’t know,” Dr. Olson said.
Other instances of life-form Lite Brite serve a clear purpose. Bioluminescence, for example, helps ocean creatures lure prey and find each other in the depths. And hummingbirds get information from the ultraviolet hues that some flowers reflect.
Fluorescence, though, is a bit more opaque. Because it’s a natural property of certain materials, “just finding fluorescence doesn’t mean it has any particular purpose,” said Sönke Johnsen, a sensory biologist at Duke University who was not involved with the study. Instead, he said, that glow could be incidental — “just something that’s there because it’s there.”
It’s unknown whether platypuses can perceive either UV rays or fluorescence, especially in natural light. One theory is that by absorbing and transforming UV light rather than reflecting it, platypuses can better hide from UV-sensitive predators.
But this is just a hypothesis, Dr. Olson said: “Our main goal is to document this trait,” in hopes that future research might shed more light. For now, his group plans to strategically investigate other nocturnal mammals, to see if they can add to their list.
They may have opened a few more museum cabinets already. “Stay tuned,” he said.