Scientists have stumbled across the reason wombats do unique cube-shaped poo.
The marsupials* produce between 80 and 100 cubes of poo each night. They can drop between four to eight pieces of poo, measuring about 2cm across, at a time.
In general, wombats use their poo to mark their territory like many other animals. They also use it to attract potential mates.
But until recently, no one has been able to work out why it is shaped like a cube.
One theory was the native marsupial had a square sphincter, the muscle that surrounds the passage to a wombat’s bottom.
But University of Tasmania wildlife ecologist Dr Scott Carver said the cubes were formed much higher in the wombat’s intestine*, rather than at the point of exit from its body.
He made the accidental discovery during a wombat dissection* several years ago and further studies led to the research being published in scientific journal Soft Matter on January 28.
“This is a puzzle with wombats that’s been around for such a long time,” Dr Carver told AAP.
“We discovered cubes inside the soft intestines. It was such an unusual thing, because how do you make cubes in a soft tube?
“It was quite contrary* to the hypotheses* out there.”
With the help of US scientists, laboratory tests and complex mathematical modelling were used to further study how common bare-nosed wombats made cube-shaped poo.
The studies found varying muscle thickness around the species’ intestines, including two stiff and two more flexible regions.
The combination of faeces* drying out in the last part of the large intestine (also known as the colon) and muscle contractions forms the poo’s regular size and corners.
“It’s really quite unusual,” Dr Carver said. “Kangaroos will often have one or two flat-ish sides but they don’t have the corners.”
Wombat intestines are about 10m long, which is about 10 times the length of a typical wombat’s body.
When humans eat, food items travel through the gut in a day or two. But a wombat’s digestive process takes up to four times longer so it can extract* all the nutrients possible from its grassy diet.
Wombats are also better at extracting water from the intestine, with their faeces a third drier than that of humans.
Dr Carver said poo was likely to play a key role in how wombats communicated with each other.
“Wombats have a really strong sense of smell. They will leave (faeces) on a prominent* rock, or a log or small rise in their home range,” he said.
“We think that it is a form of communicating who’s present and possibly other things like reproductive status*.
“We think that the cubed shape helps them aggregate*. So when they get deposited on an uneven surface they don’t roll away as much.”
4-month-old bare-nosed wombat joey cuteness
- marsupials: a group of mammals that is carried in its mother’s pouch
- intestine: the long tube that runs from the stomach to the bottom
- dissection: cutting open of a dead body to study it
- hypotheses: theory
- faeces: poo
- contrary: opposite
- extract: take out
- prominent: something that stands out
- reproductive status: whether they are ready to mate
- aggregate: collect, stay together
- How many poos does a wombat produce each night?
- Which university is Dr Scott Carver from?
- What type of wombat was studied?
- How long are wombat intestines?
- How much longer does it take wombats to digest their food compared to humans?
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1. Adapt to your audience
This incredibly interesting article about wombat poo has been written so that it can be easily understood by a wide audience of readers. However, it could be difficult for a kindergarten aged child to understand if you were to read it to them. Don’t you think this is something they’d love to know about though!? Write your own version of the article that you think would suit an audience of 4-year-olds. You could also include some simple illustrations to aid their understanding.
Time: allow 25 minutes to complete this activity
Curriculum Links: English; Science
Now imagine that instead of communicating with kindergarten children, you needed to adapt the story for a more sophisticated audience reading a scientific publication. Make a list of technical words from the original article that you would try to use. Can you identify any words from the original article that you might not use for this audience?
Time: allow 10 minutes to complete this activity
Curriculum Links: English; Science
I Spy Nouns
Nouns are places, names (of people and objects), and time (months or days of the week).
How many nouns can you find in the article? Can you sort them into places, names and time?
Pick three nouns and add an adjective (describing word) to the nouns.
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