Extraordinary claims. Ordinary investigations.

Pedalternorotandomovens Centroculatus Articulosus


"The Pedalternorotandomovens centroculatus articulosus came into being (generatio spontanea!) as a result of dissatisfaction concerning nature’s lack of any wheelshaped living creatures endowed with the power of propulsion by means of rolling themselves up. So the little animal shown here, known in popular parlance as the ‘curl-up’ or ‘sausage roll’, is an attempt to fill a long-felt want.

Biological details are still scarce; is it a mammal, a reptile or an insect? It has a protracted body made up of horny articulated sections, and three pairs of legs the extremities of which resemble the human foot. Placed centrally in the thick, round head (shaped like an acutely curved parrot’s beak), are the bulging eyes, on the ends of stalks and sticking far out on either side.

In its fully stretched position this creature can move slowly and gingerly forward, by using its six legs, over almost any type of terrain (it can, if occasion arises, climb up or down steeps, stairways, penetrate undergrowth or clamber over chunks of rock). But as soon as it needs to undertake a long journey and has the advantage of a suitable level path for the purpose, it presses its head on the ground and rolls itself up with lightning speed, pushing itself with its legs, in so far as they touch the ground. In its rolled-up position, it has the shape of a discus, the central axis formed by the eyes on stalks. By pushing out each of its pairs of legs in turn it can get up a high speed. Furthermore, it is thought ot be capable of retracting its legs and freewheeling onwards (for instance when coming down a slope or going full tilt).

Whenever it has reason to do so, it is able to return to its walking position by one of two methods:

(i) an abrupt stop brought about by suddenly stretching its body, in which case it ends up on its back with its legs in the air;

(ii) a gradual reduction of speed, using the legs as brakes and coming to a halt by slowly unrolling backwards."
[By M.C. Escher, November 1951 litograph]

Little did Escher know that nature had already created his Pedalternorotandomovens Centroculatus Articulosus. Without "generatiospontanea", as a result of the always surprising natural evolution. And not only once, but many times over, in several different variations.

Pill bugs and other armored things

Bear with me, it’s not my intention to present pill bugs (Armadillidium) as amazing wonders of nature. Even if they really are, capable of transforming into near perfect little balls able to roll around. Several other very well-known creatures such as the Armadillo, or the Hedgehog and many other animals like the less well-known Pangolin are all capable of curling up like spheres to protect themselves. To protect themselves.

[ It’s no Firefox, it’s a
Pangolin, which would also make a cool browser name ]

And here lies Escher’s genius. I guess he probably knew Armadillos and Hedgehogs, probably even Pangolins and certainly pill bugs. But those are all creatures who become sphere-shaped for protection, while Escher’s imaginary ‘thing’ becomes a wheel with the specific aim of locomotion. The wheel shape is adopted as it reduces drag over level areas allowing high speeds with little effort. As a bonus, his imaginary creatures are also able to self-propel themselves while still being a wheel.

Do you know any creature that does these things?

Escher didn’t, and “to fill a long-felt want” he invented it. But as we already revealed, nature had already come to these ways, even if science would still take some years after 1951 to discover them. So, finally…

Carparachne aureoflava

Golden wheel spiders (Carparachne aureoflava) of the Namibian desert have a somewhat harsh life. They don’t produce webs, and their defense consists in burying themselves under almost half-meter of sand. For a spider less than an inch in size, it’s quite hard work. And if their lives are difficult, their deaths may be horrible, as preying wasps are also very good sand diggers who can penetrate the spider sand fortress with a terrifying aim: to paralyze the arachnid and inject eggs inside them. The spider, still alive but paralyzed, is then buried by the wasp to become food for the growing offspring inside it. Eaten alive, from inside.

To escape from this most inconvenient end, the golden-wheel spider has one more defense mechanism. If its sand fortress is uphill, when it’s exposed by the wasp it can simply curl its legs and become a wheel, able to roll down the sand dunes. It can spin several dozen times a second, reaching a speed of up to 1m/s. For a spider less than an inch in size, it’s quite a formidable speed.

And it’s much like the imaginary animal capable of moving carefully with its legs or, when necessary, becoming wheel-shaped and rolling around to travel with speed and little effort. There’s another good video of this fascinating creature in "Buggin’ with Ruud: Golden Wheel Spider".

If the golden wheel spider fulfills Escher’s basic idea, amazingly, there’s another real creature that’s does it almost exactly the way he imagined.

Nannosquilla decemspinosa


The behavior of this little sea crustacean, Nannosquilla decemspinosa, was first described by Roy Caldwell in 1979, almost 30 years after the Pedalternorotandomovens.

It’s a creature so small and thin that it can’t walk in dry land, which is a problem when the ocean throws them in the beaches. A problem solved with some of Escher’s genius, developed through millions of years of evolution. As can be seen in the above illustration (from left to right), the little N. decemspinosa can curl-up around itself, and by doing this repeatedly, performing several dozen ‘somersaults’ as Caldwell called it – notice that it’s curling backwards – it’s the only known animal capable of wheeling itself even uphill.

Sadly, I couldn’t find any video of this fantastic little thing. But from it’s general appearance to its “wheeling” behavior, it’s almost exactly Escher’s creature living around. Escher would make a good watchmaker, as there can’t be a better proof than reinventing the wheel-shaped animals that nature’s blind watchmaker took millions of years to develop.

Keep reading for some bonus nature-wheeling.



Perhaps you are not easily impressed with animals capable of becoming somewhat imperfect wheels. Where are the axles, the free spinning wheels? Though there are no large organisms with such kind of wheels – or at least, no known organisms – at a microscopic level you will find trillions and trillions of them, as half of all the known bacteria have at least one flagellum, a tail-like structure that spins to propel them.

And it spins attached to a rotary engine made of proteins, at the molecular scale. As Andrew Goldsworthy notes, “far from nature not having invented the wheel, given the very large number of bacteria in existence, there are probably more wheels in the world than any other form of locomotion.”

But why is the freewheel not seen in large animals? The simplest answer is that the wheel is not so useful without another great, an yet much underappreciated invention. The road. There’s a nice online essay by Richard Dawkins: Why don’t animals have wheels?


The scarab or dung beetle is well-known for not only feeding on dung, but rolling them around in nice (or not so much) balls. As Gerald Scholtz argues, “the combination of rotation and the use of the low friction resistance of circular and smooth surfaces to transport a heavy load, as is seen in scarab beetles rolling dung pills, is the closest degree of similarity to a wheel found in nature.” I see his point.

Scholtz goes even further, suggesting that “populations of dung rolling scarabs may have benefited from the early domestication of large mammals in the Middle East. (…) An increased opportunity to observe pill rolling scarab beetles has inspired humans to invent the wheel.”

It certainly inspired a videogame, that’s for sure: Katamari Damacy:


There are many other examples of fictional creatures capable of rolling around as a means of locomotion, one of the most recent are the Destroyer Droids, Droidekas, from Star Wars.

And there are many other real animals capable of becoming wheel or sphere-like that we didn’t mention here. There are also recent reports that the Pangolin, rather than becoming a ball solely for protection, is also able to stretch little by little to slowly roll and flee from danger, which would make it even cooler than a Firefox. Sadly, no video either.

– – –

Keep reading:

Scarab beetles at the interface of wheel invention in nature and culture?
Real Wheel Animal – Part One
Real Wheel Animals – Part Two
Rotation in living systems
The Stomatopod and the Wheel

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Posted in Fortean,Science | 3 comments

3 Comments so far

  1. Craig York May 11th, 2009 3:44 pm

    Wonderful post! I’d never heard of either animal, though I
    had read of biological wheels showing up at the microscopic
    level. Many thanks for lightening up an otherwise dull and
    gloomy Monday.

  2. RainyRat May 25th, 2009 9:41 am

    Nice; I actually have the Escher design tattooed on my arm (see here), but hadn’t heard of “Nannosquilla decemspinosa” before.

  3. sjors dekkers March 29th, 2010 2:43 pm

    really cool. also cool you found many real animals which role up.

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