Except 9of course) the tumbleweeds. Rolling would seem to be a good way to get around-fast and low energy consumption. Any takers?
Rolling can require an axle. There is no example of such a wheel in nature*. As for rolling your ownself cross-country, I suppose it is just too dizzying.
*OK some joints, but that is about it.
There’s the infamous cartwheeling spider.
The hoop snake;
My cat does front somersaults.
Yeah, if you only had to go downhill or downwind. But at some point one must be able to travel uphill, so there needs to be a mechanism for that - and having something to facilitate rolling in addition to whatever gets one uphill would use up some resources and add complexity. More to be lost than gained, I’d say.
That’s real, right? I was sure it was gonna be a spoof, but it looks real. Remarkable!
And rolling doesn’t require an axle (I’m not sure how “can” can modify “require”). Otherwise, nobody can ever roll a ball.
I’m certain I saw a documentary featuring a small lizard that did something similar.
I also found sketchy descriptions of the Venezuelan Pebble Toad which rolls downhill to escape from predators - might be apocryphal though.
I believe there are some, but they are only in microscopic-sized organisms.
The Master speaks:
Those Irish-sounding pacifist quasi-lemurs in the most recent Clone Wars episode.
This was the first thing that popped into my head, especially since I just read about that recently, right here on the SDMB!
EDIT: actually, I’m not sure, but that Youtube video may be talking about a different kind of spider. That one only seems to roll downhill as a means of escape, while the spider recently discovered by Professor Rechenberg uses it as a form of locomotion even across flat ground.
The Escherian Treppenhaus?
You are probably thinking of rotifers, or “wheel animalcules.” They don’t actually have wheel-like structures; the appearance of spinning is due to the motion of cilia.
How about Mic, Keith and the boys?
The Dung Beetle. It shapes the dung into a ball and rolls it where it’s going. The rolling dung sometimes carries some of the beetle’s own weight. When it doesn’t the beetle is nonetheless benefiting from rolling motion.