John Gould was in the Watagan Mountains when he made a remarkable and accidental discovery - he spotted a beetle walking upside down on water.
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The University of Newcastle behavioural ecologist pulled out his smartphone and caught the moment on video.
It's thought to be the only known visual evidence of the unique ability of aquatic beetles to walk on the underside of the water's surface.
"I came across the beetle purely by chance while doing fieldwork for my PhD," Mr Gould said.
"As part of my research, I was searching small, ephemeral pools for tadpoles of an Australian frog.
"In one of the first few pools I went to, I didn't find any tadpoles but saw this small black object moving across the surface of the water."
At first, he assumed it was a bug that had fallen in the water and was swimming across the surface.
"A part of me wanted to help it out, but as a biologist you avoid interfering with nature if possible," he said.
"It was only after observing the beetle for a little while that I realised it wasn't swimming, but actually walking upside down and below the water's surface."
It was late at night when he spotted the 6mm to 8mm beetle, but any sense of tiredness was replaced by excitement.
"I always make it a habit to have my phone in my back pocket whenever I'm out in the field doing research," he said.
"When I realised the beetle was doing this incredible thing, I quickly grabbed it and started recording.
"Luckily, I was wearing a head torch and there wasn't any wind, so I could get a really good recording close up."
Mr Gould said the beetle's behaviour was "so peculiar and almost gravity defying".
He took the video a few years ago while doing his PhD and didn't show it around until a few months ago.
"I thought it was pretty cool but was busy trying to complete my studies, so it was almost like this secret footage I had locked away and forgotten about."
The find has now been published in the Ethology journal.
"I showed the observation initially to Jose Valdez, a wildlife ecologist at the German Centre for Integrative Biodiversity Research.
"He became a co-author of the paper and really helped in developing some of the hypotheses we pose.
"We propose that the beetle may use this unusual location for walking to avoid predation."
Many predators wait patiently for prey at the bottom of the water or along submerged vegetation.
"By walking along the underside of the surface, the beetle may avoid these predators," he said.
"It does, however, expose them to other kinds of predators that move through the water.
"We suspect that the small size of the beetle and the lack of rippling it produces at the surface while in motion may let it get by undetected."
The paper said the beetle "possessed a layer of trapped air along its abdomen".
"We propose that the air bubbles located on the abdomen and/or legs may be providing the upward force necessary for the beetle to be pushed against the underside of the water's surface," he said.
"It is likely that the water's surface is acting purely as a support for the beetle, with its gait generating the force that drives it forward."
The paper said the discovery "adds to the small number of observations of animals using the underside of the water's surface to move".
The beetle was unidentified, but thought to be from the Hydrophilidae family.
Mr Gould has recorded other strange behaviours in the field over the years.
This included a slug that superglued a frog to a branch, and a slug that used a mucus bridge to get to the ground.
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