Scientists explain how wombats drop a shit into cubes

The wombats, short-legged marsupials, beloved and beloved, native to Australia, are at the heart of a biological mystery in the animal kingdom: how do they produce a cub-shaped dung? Patricia Yang, a postdoctoral fellow in mechanical engineering at the Georgia Institute of Technology, has launched an investigation.

Yang studies the hydrodynamics of fluids, including blood, processed foods and urine, in the body of animals. She was curious to know how differences in the digestive processes and soft tissue structures of wombats could explain their strangely shaped dispersion.

During the 71st annual meeting of the Fluid Dynamics Division of the American Physical Society, to be held from 18 to 20 November at the Georgia World Congress Center in Atlanta, Georgia, Yang and his co-authors, Scott Carver, David Hu and his undergraduate student, Miles Chan, will explain their discoveries during the dissection of food systems, or digestive tract, wombats.

"The first thing that led me to that is that I've never seen anything so strange in biology – it was a mystery," Yang said. "I did not even believe it was true at first, I googled it and I saw a lot on the cube-shaped wombat poop, but I was skeptical."

Yang and his co-authors studied the digestive tract of wombats that had been euthanized as a result of motor vehicle collisions in Tasmania, Australia. Carver, a biologist and Australian counterpart of the group of American mechanical engineers, provided the intestinal specimens of the wombat.

Near the end of the intestine, they discovered that fecal matter was passing from a liquid state to a solid state consisting of small, separate cubes. The group concluded that the variable elastic properties of the intestinal walls of wombats allowed the formation of cubes.

In the built world, cubic structures – sugar cubes, sculptures and architectural features – are common and are produced by injection molding or extrusion. Cubes, however, are rare in the natural world. Currently, wombats are the only known species capable of producing cubes biologically.

"We currently have only two methods to make cubes: we mold them or we cut them in. We now have this third method," Yang said. "It would be an interesting method to apply to the manufacturing process: how to create a cube with soft tissue instead of molding it."

So, why are wombats pooping? The wombats stack their feces to mark their home range and communicate with each other through the scent. They pile up their excrement in conspicuous places (for example, next to burrows, or on logs, rocks or small elevations) because they have poor eyesight. The higher the pile of excrement is and prominently displayed, the more visually distinctive it is to attract other wombats to feel and communicate. Therefore, it is important that their droppings do not roll and the cube-shaped shit solves this problem.

Yang hopes that the group's research on wombats will contribute to the current understanding of soft tissue transport or how the gut is moving. She also pointed out that the group's research focused on mechanical engineering and biology and that their results were valuable for both areas. "We can learn from wombats and hopefully apply this new method to our manufacturing process," Yang said. "We can understand how to move this material very efficiently."

Carver added, "The public, in Australia and around the world, are very interested in how the wombats create cube-shaped droppings, many ideas, some more entertaining than others. , have been put forward to explain that no one had ever investigated the cause, it is a fantastic collaboration that shows the value of interdisciplinary research to make new scientific discoveries. "

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More information:
Presentation E19.1, "How do wombats poop in cubes?" Patricia J. Yang, Miles Chan, Scott Carver and David L. Hu, will be present on Sunday, November 18th at 5:10 pm in Room B306 of the Georgia World Congress Center in Atlanta. Summary: meetings.aps.org/Meeting/DFD18/Session/E19.1