This hopping mouse produces solid urine to cope in the harsh Aussie desert

By Angela Heathcote 18 January 2018
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Meet the spinifex hopping mouse— they may look small but they thrive in Australia’s harshest environments.

THE SPINIFEX hopping mouse (Notomys alexis), also known by its traditional Aboriginal name tarkawara, thrives in the red-hot arid zone of Australia, where they play an important role in maintaining the ecological balance. 

According to Dr Alex Kutt, a landscape ecologist at Bush Heritage, who’s interacted with this particular hopping mouse for around four years, the unique desert mammal is both a seed eater and a seed disperser.

“From and ecological perspective they effect all levels from the soil, through to the vegetation, while also being a food source for other native carnivorous mammals and birds of prey, like owls,” he tells Australian Geographic.

Solid urine

However, the mouse’s most unique feature is the way they’ve evolved to conserve water so that they can continue thriving in Australia’s harsh desert climate.

This particular species of hopping mouse is said to have the most efficient, albeit tiny kidneys, which allow them to produce the most concentrated urine of any mammal ever recorded.

“They get most of their water from the things they eat, so they’re really good at processing the water out of their food,” Alex says.

“The kidneys continue to recycle and re-absorb water from the food they eat. They end up with a urine that’s pretty much solid, consisting of only the waste material that they want to get rid of from their body.”

According to a 2008 study of the kidney functions of the spinifex hopping mouse, the efficieny of their kidneys is characteristic of a well-insulated renal medulla, which is the innermost part of the kidney.

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A spinifex hopping mouse in action. (Image Credit: Annette Ruzicka/Bush Heritage)

Adapting to the desert

According to Alex, not only do their complex kidney structures allow them to manage the effects of the desert heat, but also their big feet. 

“Hopping is a very efficient way of moving through the landscape as it helps them conserve their energy. Their big feet allow them to cover wider surface areas.”

And their adorably large ears have an important role to play.

“They have big ears, which help them not only listen for predators but also helps cool them down. 

Like many desert animals, Alex says they construct complex burrowing systems.

“They’re burrowing habitat is critical. They need to create a cool home.

“They have these complex burrow systems that have one primary burrow entrance that leads to a sleeping chamber.

“They burrow will also usually include ‘pop holes’, like vertical tunnels, that go up out of that system allowing them to escape quickly if a python comes down the burrow.”