Sci&Tech’s Imogen Claire reports on how scientists squared up to the mystery of the Wombat’s poo

A girl has no name. Because it keeps being written down differently.
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Wombats, the grumpy and tubby Australian marsupial, poop in cubes. It is the only known species on the planet to poop in cubes. That fact on its own is fantastically weird and you’re already committing this to memory to impress at the next house party or night at the pub – you must be so worldly and travelled to know wombat digestive tract trivia. All levity aside, it is the mystery that plagued zoologists, surfaced in their nightmares, threatened to topple the animal kingdom itself. Why? Why do wombats poop in cubes?

These dark days are over. A group of researchers at the Georgia Institute of Technology presented their work on the wombat’s cubic conundrum at the American Physical Society Division of Fluid Dynamics’ annual meeting in Georgia. The team used the bodies of Tasmanian wombats euthanised after traffic collisions to investigate their research questions. Comparing these intestines with those of pigs, a balloon was pushed through the digestive tract to see how the tissue accommodated the balloon.

What the researchers found was that the wombat intestine wall is variably flexible in the final 8% of the organ, which alternates to create the cube shape. Pig intestines do not possess such irregularity in elasticity, and so the mystery is solved. But, the motivation for this phenomena is still unknown and so the evolutionary advantage of a six-sided poop will be revealed.

Wombats are intensely territorial animals, greeting any intruder to their home base – which could range up to 23 hectares, centred around their burrow – with unmetered aggression. Producing 80-100 cube poops each night, wombats use the poops to mark territory very effectively. The shape stops droppings from rolling away from the site, and the animals will even stack their poops to communicate and attract other members of the species.

The practical implications of these findings are slightly intriguing. At present, artificial cubes of soft materials are produced by cutting or moulding. Researchers suggest that this could be a new approach to effectively building cubic shapes with appreciable structural integrity.

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