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There have been several discussions both on this website and others about the viability of wheeled animals and why there are no current biological examples of it. A big issue with an animal evolving wheels instead of legs is that an intermediate step between wheels and legs would be useless and the animal would be immobile. Another issue with wheels is that the wheels have to be somewhat separate from the organism or otherwise the blood vessels would get knotted up or torn up. If the wheels are attached however, the organism would have to entirely flip over to move.

Let's say however that some aliens genetically engineer a wheeled animal and release it on Earth. This animal would be similar to a lizard and lives in large, open areas like salt flats. Since the animal is genetically engineered, the useless evolution reason no longer applies. The other big issue is how to separate the wheels from the rest of the animal. Some animals have inorganic hair and exoskeleton that they use. Other animals like lizards can lose and regrow body parts. Therefore, the genetic engineered species can grow wheel and axles and detach them. Then it can hook onto the detached wheels and axles and use them.

Could this wheeled lizard be a viable species or are there other issues that stop a wheeled animal from thriving in a niche?

ITM_Coder
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    Seems unlikely, think in terms of repair. Say part of the wheel rim gets damaged, flesh and blood can regrow to a certain extent but a detached wheel is just going to be chipped or flatted or whatever. – SoronelHaetir Sep 01 '22 at 19:55
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    Another problem is friction - in live organs it is addressed very well, but live organs are enclosed. Wheels, on the other hand, would have to be dead organs, and their axles would need to be continually lubricated from live organs. – Alexander Sep 01 '22 at 20:26
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    What exactly do you mean by a viable? Seems like anything engineered to fill a niche will by definition be suitable for that niche. – sphennings Sep 01 '22 at 22:12
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    @sphennings "What exactly do you mean by a viable? " It seems pretty obvious to me .. Coder is asking if their are any major reasons a wheeled animal can't work or exist other than the "intermediate step between wheels and legs would be useless" issue that makes the possibility of natural evolution (and thus in the normal course of things the existence of such an animal) so doubtful .. To the close voter, I don't believe this question needs clarity, it is perfectly clear to me what is being asked, perhaps you have some other issue with it and simply clicked the wrong close reason? – Pelinore Sep 02 '22 at 01:47
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    To the closers, the question doesn't have answers on the question you have linked, having reviewed them they all rely on the specific condition that this question has specifically removed (the difficulty of such a thing evolving naturally) to say 'no', or else talk about an alternative to actual wheels where the whole creature rolls, the question you have linked is not a duplicate either because it asks if it is evolutionarily plausible which this one specifically does not, could you elaborate on your reasons for closing? because they don't seem to be accurately summarised by the close notice. – Pelinore Sep 02 '22 at 08:22
  • @SoronelHaetir This isn't a strong criticism. We have examples of organisms that deposit layers of hard materials onto surfaces all over the place. Do oysters not deposit nacre onto grains of sand/grit such that these become pearls? – John O Sep 02 '22 at 14:24

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What you're really looking for is a creature that grows a chitinous wheel instead of a shell. They would need to have a "wheel well" organ that added material to the wheel in layers, and muscles that gripped the wheel and used it to push the creature along.

Let's presume that the wheel is semi-toroidal; a disk that is thinner near the center. The creature would spend its immobile periods slowly depositing new material on the outside of that wheel so it grew as the creature did, or so that it could replace parts that got damaged. This organ would be a cross between an eye socket, a nail bed, and the foot of a snail. You probably wouldn't get much speed out of that configuration, but this creature is genetically engineered, so it could have multiple motion options, the same way we have walking and running.

For faster motion, bony axles would extend and connect to the inside of the wheel, while the foot-socket pulled back to act more like a fender. This wouldn't be sustainable indefinitely, but neither is running.

The "lizard" part is completely immaterial. This is genetic engineering, so the base genome is kind of meaningless.

Thriving is another issue entirely. Wheels just don't work well in lumpy environments, and any natural environment would be lumpy. If you had an environment that was particularly flat, then they might be able to survive as long as the variations in surface didn't exceed half of the wheel's height. This might mean a prolonged period for offspring to be dependent upon their parents.

Overall, though, you'd always have to do a bunch of scientific justification for how all of this could work.

Robert Rapplean
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  • How are the wheels turned in these two movement modes? In the first mode, there seems to be a need to release the wheel rather frequently to let the muscles unwind. In the second, there's no obvious motive force at all. – John Dallman Sep 01 '22 at 21:12
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    Instead of being turned by a biological motor, perhaps they could be propelled along by an alternate "tacking" movement, like rollerblades? – Escaped dental patient. Sep 01 '22 at 21:18
  • @JohnDallman, In the initial movement mode, the motion is caused by pulling and stretching, identical to that of a gastropod's foot. You aren't going to get fast movement from that. In the second, I was expecting that the gastropod feet would be partially disengaged, essentially pushing it with the same kind of motion as a human pushing a wheelchair, but with a lot more pads. Braking would be hard. – Robert Rapplean Sep 01 '22 at 21:44