How do we put it? In the world of animal dung, there's everyone else's ... and then there's wombat poop.
Because no matter the size, shape, colour, smell, or consistency of a creature's droppings, only wombats have the ability to poop in cubes. What's that? You haven't heard? Well, it's true.
Wombats poop cubes.
In addition to being frankly super cute, it is also completely remarkable. After all, square are a very rare shape in nature. Animals and plants do plenty of circles and curves—very few sharp edges and hard corners.
— Diana S. Fleischman (@sentientist) November 3, 2016
So how do wombats manage to poop this way?
Round tube, square poop?
All animal feces—our own included— follow the same basic route. After food is digested and all available nutrients have been extracted, it moves through the large intestine. There it is compressed and broken down further by bacteria until it is ready to be pooped out through the anus.
In all cases, the tubes and openings are circular. Which is why, whether you're talking tiny rabbit pellets or huge elephant droppings, the shape is spherical or cylindrical. Round tubes and openings produce round shapes.
By this logic, we'd expect wombats to have squares somewhere in their bodies. But their anus is a circular opening, just as in other animals. And at first glance, their intestine appears to be a cylindrical tube, too. What gives?
Fortunately for us (because not only do we want to know, we don't want to be the ones to figure it out) Patricia Yang from Georgia Tech put wombat guts to the test. She and her university colleagues compared wombat intestines to those of a pig. By inflating these organs like a balloon, she found her answer.
The pig intestine inflated uniformly, or evenly. It was all the same elasticity, so whatever waste passed through it was formed into a smooth cylinder. But the wombat intestine had stiff areas—or grooves—in between the more elastic areas. The result? When waste passed through it, it stretched into a square-shaped tube. The result? Poop with four corners that broke off in little cubes!
Of course, the next question is obvious. What are wombats adapted to do this?
One leading theory is that because wombats use their poop to mark their territory, having square poop means that it won't roll away. That's an amazing theory, though not every scientist is sold. Others just think that it has to do with the fact that in their dry habitat, wombat bodies are simply trying to extract every ounce of moisture from their food. Their intestines squeeze it extra hard before passing it on as waste.
Whatever the real 'why' is, it certainly won't make the 'how' any less fascinating!