[cjhveal]

I'm probably just misunderstanding the physics involved, but wouldn't moving the container only impart movement on the fluid inside in proportion to the viscosity of the liquid? And once the fluid is moving wouldn't stopping it require movement in the opposite direction or waiting for friction to reduce the inertia of the fluid?

I'm thinking of the behavior of the semicircular canals of the ear, and how the inertia of the endolymph can cause dizziness after spinning for a while.

Maybe the critical part I'm missing is that the organism is actually sinking in the fluid around it and the effect of fluid current if present is minimal compared to the effect of gravity.

As an aside, the homepage for this project is quite nicely illustrated.

[devindotcom]

I had this exact question, and the researchers said it was a serious consideration. Turns out the critters at this scale move quite slowly and so does the wheel. There's some effect certainly but it's small enough that they can track a single organism for quite a long time. It wouldn't work in other circumstances or scales for sure.

I wrote it up here, in case anyone would like to read about it in article form: https://techcrunch.com/2020/08/19/this-looping-aquatic-tread...