Critters Don't Have Wheels

Several organisms are capable of rolling locomotion; however, true wheels and propellers—despite their utility in human vehicles—do not appear to play a significant role in the movement of living things (with the notable exception of certain flagella, which function like corkscrews). Biologists have expounded on the reasons for this apparent absence of biological wheels, and wheeled creatures have appeared often in speculative fiction.

Given the ubiquity of the wheel in human technology, and the existence of biological analogues of many other technologies (such as wings and lenses), the lack of wheels in the natural world would seem to demand explanation—and the phenomenon is broadly explained by two main factors. First, there are several developmental and evolutionary obstacles to the advent of a wheel by natural selection, addressing the question "Why can't life evolve wheels?" Secondly, wheels are often at a competitive disadvantage when compared with other means of propulsion (such as walking, running, or slithering) in natural environments, addressing the question "If wheels could evolve, why might they be rare nonetheless?" This environment-specific disadvantage also explains why some historical civilizations have abandoned wheels.

Biological Barriers to Wheeled Organisms

The absence of wheels in nature is frequently attributed to constraints imposed by biology: natural selection constrains the evolutionary paths available to species, and the processes by which multicellular organisms grow and develop may not permit the construction of a functioning wheel.

Disadvantages of Wheels

Wheels incur mechanical and other disadvantages in certain environments and situations that would represent a decreased fitness when compared with limbed locomotion. These disadvantages suggest that, even barring the biological constraints discussed above, the absence of wheels in multicellular life may not be the "missed opportunity" of biology that it first seems. In fact, given the mechanical disadvantages and restricted usefulness of wheels when compared with limbs, the central question can be reversed: not "Why does nature not produce wheels?", but rather, "Why do human vehicles not make more use of limbs?" The use of wheels rather than limbs in many engineered vehicles can likely be attributed to the complexity of design required to construct and control limbs, rather than to a consistent functional advantage of wheels over limbs.

Wheeled Creatures in Fiction

Toy animals with wheels dating from the Pre-Columbian era were uncovered by archaeologists in Veracruz, Mexico, in the 1940s. The indigenous peoples of this region did not use wheels for transportation prior to the arrival of Europeans.

                                      Toy animal with wheels from pre-Columbian Mexico

Several twentieth century writers explored possibilities of wheeled creatures. L. Frank Baum's 1907 children's novel Ozma of Oz features humanoid creatures with wheels instead of hands and feet, called Wheelers. Their wheels are composed of keratin, which has been suggested by biologists as a means of avoiding nutrient and waste transfer problems with living wheels. Despite moving quickly on open terrain, the Wheelers are stymied by obstacles in their path that do not hinder creatures with limbs.

In the latter half of the twentieth century, wheeled creatures were featured in works by fantasy and science fiction writers including Clifford D. Simak, Piers Anthony, David Brin, K. A. Applegate, Philip Pullman, and Ian Stewart and Jack Cohen. Some of these works address the developmental and biomechanical constraints on wheeled creatures: Brin's creatures suffer from arthritic axles, and Pullman's are not born with wheels, but use seed pods found in their environment.

                 https://en.wikipedia.org/wiki/Rotating_locomotion_in_living_systems