Escher, in his own words, invented the creature "as a result of dissatisfaction concerning nature's lack of any wheel-shaped living creatures endowed with the power of propulsion by means of rolling themselves up."
"In its fully stretched position this creature can move slowly and gingerly forward, by using its six legs, over almost any type of terrain... 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 its rolled-up position, it has the shape of a discus, the central axis formed by the eyes on stalks.... Furthermore, it is thought to be capable of retracting its legs and freewheeling onwards (for instance when coming down a slope or going full tilt)."
In 1951, Escher invented the 'Curl-up', as its come to be called, "to fill a long-felt want". Almost 30 years later, he might not have had the need.
In 1979, Roy Caldwell observed the small stomatopod Nannosquilla decemspinosa (Rathbun, 1910) performing a feat Escher only dreamed off.
N. decemspinosa is found amongst the intertidal sands along the Pacific coast of Central and South America. Reaching a length of 23mm, the predatory marine crustacean is a 'spearer', lying in wait at the entrance to its shallow water burrow, ready to ambush any soft-bodied fish or crustacean.
As may be deduced, these incredibly small crustaceans with their thin, elongated bodies can't walk on dry land which poses a problem when the ocean waves toss them up on the beach - a problem solved thanks to evolution. Much like Escher's Pedalternorotandomovens, N. decemspinosa has the ability, when thrown up the beach, to curl-up around itself repeatedly, 'somersaulting' back to the shallows. And by curling backwards, it becomes the only known animal capable of wheeling itself uphill (hmm... walk-cycle, anyone?).
And while there are many organisms that capable of rolling themselves in to near-perfect little balls - the pill bug, armadillo and pangolin* - very few actually use it for locomotion. In the Namibian desert, the Golden wheel spider uses it to evade predatory wasps, curling its legs in towards it's body and rolling downhill. Rolling uphill, however, is another matter.
In the end, Nannosquilla decemspinosa stands alone as an evolutionary marvel only an artist could dream up† - life evolving in to art.
†Unless, of course, you believe all that nonsense about the 'Fifth Day'.
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