A team of scientists claims to have unraveled one of the most peculiar mysteries of the animal kingdom: why the wombat poo is cube-shaped.
The wombat, native to Australia, produces between 80 and 100 cubes of poop per night. It is known that it uses manure to mark its territory, depositing piles of things outside burrows and on rocks and logs, according to Australian Geographic.
But how the wombat produces the shapes in cubes is a phenomenon that has baffled many observers of the furry marsupial.
The researchers, led by Patricia Yang of the Georgia Institute of Technology, said they discovered the digestive processes behind the mystery and presented their findings at the 71st Annual Meeting of the Fluid Dynamics Division of the American Physical Society in Atlanta on Sunday.
Stool cubes of the wombat is a trait that is unique in the animal world, researchers said, since cubes are usually created by cutting or molding.
"In the built world, cubic structures are created by extrusion or injection molding, but there are few examples of this feat in nature," the project authors said in the study summary.
To solve the puzzle, the team examined the digestive tracts of wombats that had to be sacrificed after vehicle collisions in Tasmania, Australia.
The wombat takes about two weeks to digest its food and the researchers found that as the stool moves toward the final 8% of the intestine, it changes from a liquid state to solid matter. At that stage, the manure takes the form of separate cubes that measure approximately two centimeters in length.
By inflating the intestine with a long balloon, the researchers found that the bowel walls of the wombats are stretched unevenly, allowing the formation of the cube shapes.
"The local tension varies from 20% at the corners of the cube to 75% at its edges," the team said. "Therefore, the intestine is preferably stretched on the walls to facilitate the formation of the cube."
The study authors said the findings could have implications beyond the natural world, by helping to provide information about new manufacturing techniques.