Humans May Work in Cubes but Only Wombats Poop Them
The peculiar world of oddly-shaped animal droppings.
In a past uBiome newsletter, we reported on the ingenious Bristol Stool Scale, a system that categorizes human poop by its shape and consistency.
In a version designed for children, it helpfully compares different types of poop to sausages, chicken nuggets, porridge, and gravy.
uBiome often shares how poop shapes our work. This time, though, we’re focusing on the various shapes of poop.
If you’re currently eating, and depending on whether it’s breakfast or lunchtime, sorry to put you off your porridge or nuggets.
One thing’s certain, though. If you peek into the pan after moving your bowels, you’re unlikely to find cube-shaped poop floating around down there.
Unless, of course, you’re a wombat.
We have our wise Science Editor, Elisabeth Bik, to thank for pointing out that the wombat is the only creature in the world to produce cubic poop. Elisabeth’s years in academia weren’t wasted.
It got us all fired up to look into the world of non-human droppings, beginning with an exploration of what it is that causes wombats to poop this way.
Wombats, native to Australia, live mainly underground, sleeping for around 16 hours a day.
They’re nocturnal, so they only come out of their burrows at night, and when they do, they struggle with terrible eyesight, instead relying heavily on their sense of smell.
Their myopia, of course, doesn’t explain the wombat’s cube-shaped poop, nor does the lack of a square anus.
(Just as we can’t believe we just wrote that, you probably can’t believe you read it, either.)
Anyway, wombats have incredibly long digestive tracts, and an equivalently slow digestive process.
If you’re a wombat, we’re talking 14 to 18 days from food to fecal matter.
The first part of a wombat’s large intestine contains horizontal rings, a bit like a vacuum cleaner hose, and it’s thought that this configuration initially chops up compacted fecal matter into distinctive cube-like pellets.
The lengthy digestive time means wombat poop becomes extremely dry and compacted, so the animal’s rectum isn’t able to reshape poop into the tubular shape that’s much more common in the animal kingdom.
Robyn Lawrence, an Australian outback enthusiast, has helpfully produced a video of her home-made wombat gastrointestinal tract (every home should have one), which squeezes perfect cubes from its plastic bottom when she “feeds” it with Jell-O.
Wombats’ dismal eyesight, coupled with their territorial nature, means their sense of smell is vital in warning off enemies, so they deposit their poop as a kind of invisible, but smelly, barrier.
It’s where the shape of the 80 to 100 cubes they pop out every night comes in handy.
You see, it allows wombats to make deposits on logs and rocks that stay in place.
If they were rounded, they’d roll off.
Clever old nature, eh?
Two other animals with distinctive poop are rabbits and cows: rabbits producing pellets, and cows – well – splatting.
Actually, vets use the consistency of a cow’s manure to get a handle on its health and diet.
A healthy, lactating cow should produce feces with the consistency of porridge, forming a dome-shaped pile one or two inches high when freshly dropped.
A liquid, pea-soup-like consistency suggests a diet with too much protein, whereas bovine excrement resembling a horse’s dung indicates insufficient protein and starch in the animal’s feed.
Leave it to the Ministry of Agriculture, Food and Rural Affairs in Ontario, Canada, though, to supply helpful instructions to farmers wishing to perform their own cow manure analysis.
Forget the DNA sequencers we use at uBiome – the Ministry recommends using a simple kitchen sieve, appropriately reminding you to procure a dedicated utensil, rather than simply borrowing one from the farmhouse drawer.
The methodology involves loading your sieve with cow poop, then holding it under a running tap to see what’s left behind after the brown stuff (which can often actually be pretty green) has washed away.
As a Canadian cow farmer, you’d be interested in the fibers and undigested grains left in your sieve.
Alongside cows, we mentioned rabbits as having distinctive droppings. You’ll almost certainly have noticed them while walking in open spaces.
What’s pretty fascinating about rabbits, though, is that they actually produce two distinct types of droppings.
There are the fecal pellets – those round, dry ones you see everywhere and which, by the way, dogs love eating – but rabbits also produce what are called cecotropes.
Not only do they produce them, they also, uh, eat them – often the minute they pop out of their own rear ends.
But there’s method to this apparently yucky madness.
Cecotropes are formed in a part of the rabbit’s gastrointestinal tract called the cecum – a blind-ended pouch at the junction of the small and large intestines.
The cecum contains a natural community of bacteria and fungi that provides essential nutrients, and likely protects the rabbit from dangerous pathogens.
So eating them makes sense.
Domesticated rabbits tend to go through this process when nobody’s around (well, wouldn’t you?) so it’s unusual to see an uneaten cecotrope, but they look a little like an elongated brown raspberry, made up of a bunch of small, soft, shiny pellets, each coated in a layer of rubbery mucus.
Now, if we didn’t put you off your breakfast or lunch earlier, that’s probably done it for your dinner now.
By the way, although the idea of dogs tucking into rabbit droppings is pretty icky, there’s often good cause for their behavior, as the little pellets can be rich in digestive enzymes and vitamin B.
These enzymes can be important for dogs who mainly eat dry food, although because of the risk of picking up parasites, it’s not something to greatly encourage.
You won’t find cube-shaped poop on the Bristol Stool Scale.
Maybe on the Brisbane Stool Scale, though.