While there is still no known animal with, as you say, a wheel and axle, there is at least one spider that has evolved a wheel-like form of locomotion. It is a desert spider that spreads its legs and rolls, wheel-like, down sand dunes. I can’t give you anymore info-saw it on a nature show a couple of years ago, and the image stuck with me, not the show’s info.
Why has no animal species ever evolved wheels?
This question always makes me think of these weird critters in an MC Escher print that had big beaks six human feet. They could coil up into a wheel and roll along. Their eyestalks formed a sort of axle, but it didn’t connect to anything. Funny stuff.
The spider trick is genuine; they tuck their legs in, and roll down the sand dune. Many dune-inhabiting beetles are rather round and prone to rolling when disturbed.
However, there are organisms that possess a genuine wheel - many bacteria, including one that’s rather abundant in our own bodies, Escherischia coli. The mechanism by which a bacterial flagellum turns is quite a bit like a wheel; more precisely, like a power screwdriver - a long corkscrew with a disc at its base, with ball-bearings, set in a socket so it can spin. This is one of those things the nanotechnology folks are really fond of, but I’m not sure that anyone really understands how the flagellum is powered.
Thanks, Doug. But many people discount microscopic life forms when they talk about “animals,” they’re thinking critters, not microbes (not me). Besides, you’d expect esoterica when thinking on the microscopic scale. With new generations every 20 minutes or so, and the ability of microbes to exchange DNA even across species lines, you get much more milage out of your mutations…
More to the point, bacteria do not have or need blood vessels or nerves.
or roads…
Or cup holders, etc.
It would be kind of cool, though-some kind of ATV (All Terrain Vermin).
“The new, 2003 Jeep Gerbil!”
Just thinking some more though, another reason you wouldn’t see an animal with wheels-too easy to kill. Even if one did evolve, once you flipped it over on its side or back, it would be a goner. It wouldn’t have a way to flip over-no limbs to flail about…
The problem with wheels is “how does one feed blood supply, nerves, muscles etc to the rotating appendage?”
Keep in mind that evolution works in response to the environment, not the other way round.
Did you read the article? There’s a link to it in the second post here. That may address your concern.
No, I didnt - I responded to the particular post first then I finished the thread to recognise the error I made.
Eh? No problem. Just letting you know there’s a pretty inventive solution to the problem you pose.
It’s hard to imagine a living wheel - there’s no way to get macroscopic structures from the main body to the wheel without twisting with each revolution. You could have blood vessels leading to the axle of the wheel, with thin tubes leading out to the outside of the wheel.
Then again, why not have the wheel made of inanimate material like bone? The only things which have to be fed are the mucles which turn the wheel.
Oh right I just read Cecil’s thing on merry-go-round umbilicals. Cool, that - I couldn’t do it in my head at first, then realized that the tape is firmly fixed to the table.
What about variations on the hoop snake, but active? I mean, there are several ideas I have which can accelerate at will and go uphill -
- a large hoop with small, simple appendages lining the outside in multiple rows. Each toe can pull in two directions. Pulling and letting go slack when the toe’s part of the hoop is about to lift will give some push to the whole contraption. Of course, the toes have to be tough and not missed - like shark’s teeth, constantly renewed.
- an active hoop - I suppose the snake is like this. Bending the part of the hoop just in front of the ground so that the whole thing falls in that direction, flattening that part and beding the next… again and again, and you’ve got motion in two directions.
Bone is not as dead as you might think-don’t forget the marrow. A modified hair (like a rhino’s horn) or hardened skin (like fingernails) would be better…
Though not used for locomotion, the colossal squid has hooks on its tentacles that can rotate 360 degrees, so the mechnism is not limited to one celled life forms:
Well look to the left and to the right-your arms can rotate through a 360deg. plane as well, but we don’t call them wheels.
For wheels to be really efficient first you have to evolve roads… a bicycle is the most efficient way of using human muscle power,
but becomes much less efficient when the surface it travels on becomes uneven and irregular.
Imagine a colonial organism that produces smooth pathways for the translocation of resources, and the situation cries out for wheels or ball bearings of some sort.
Humanity is the only colonial organism that I am aware of which has adopted this strategy.
Well, if form follows function, eubracum45 probably just nailed it. Wheels are made for rolling over smooth surfaces, and but for the sand dune spider, we don’t have animals living in smooth ecosystems.
Isn’t that what the man said?
The man being Cecil, obviously.