[TheLoneWolfling]

Note that there are organisms that include "wheels" (Or rather, rotary motion in general).

It's "just" that the only organisms on Earth that do so are microorganisms. Look at flagella.

But there's nothing inherent about rotary motion that is impossible for organics to do. It's "just" that there is no clear evolutionary path from something that relies on linear actuation to something that relies on rotary actuation.

(Also, note that there are pumps that are continuous that don't rely on rotary motion. Among other things, you can have two+ sacs, each with an inlet and outlet valve that can contract and expand. One expands while the other contracts, and vice versa. There's still some variation while the changeover happens - but this can be avoided if you have >2 sacs. Alternatively, there are peristaltic pumps that work continuously that can be implemented with only linear actuators. (As a bonus, this means that you don't need a centralized pump. You can integrate it into the blood vessels themselves.)

The bigger limitation tends to be respiratory, actually. Earth has only ~21% oxygen currently. You bump that up (causing all sorts of other problems), you can have faster and/or larger critters. Alternatively, you have more efficient lungs (Note that human-style lungs are relatively inefficient. Ideally you want air to flow in one direction through the lungs instead of alternating... Birds do that, IIRC.) and/or more efficient oxygen / CO2 transport in the blood. Red blood cells are not exactly efficient. (There was an Analog article at one point about diamond spheres for artificial red blood cells. A related article, https://www.foresight.org/Nanomedicine/Respirocytes3.html, says the following "In the absence of respiration or atmospheric oxygen, a fully-O2-charged augmentation dosage consisting of 9.54 x 10^14 respirocytes could provide tissue oxygen delivery and carbon dioxide removal for 12 minutes at peak exertion and 3.8 hours at rest even during cardiostasis" "A 1-liter augmentation dose increases blood O2 storage capacity 18,000%")

[rcthompson]

There's another example of biological rotary motion at the microscopic level that is used by pretty much every living organism: ATP synthase[1].

[1] https://en.wikipedia.org/wiki/ATP_synthase