Does the stalk contractility of \textit{Vorticella} \textit{convallaria} depend on the stalk length?*

\textit{Vorticella convallaria} is a sessile stalked ciliate living in water, and its stalk coils to move the cell body (zooid) towards its residence substrate at a maximum speed of $\sim$ 50 mm/s. Our previous microfluidics study shows that the isometric tension of the \textit{V. convallaria} stalk is linearly proportional to the stalk length. Based on this observation, we hypothesize that the contractility of \textit{V. convallaria} during normal contraction is also dependent on the stalk length. To investigate our hypothesis, we measured the contraction speed of \textit{V. convallaria} using high-speed videography and evaluated the contractile force and energetics of \textit{V. convallaria} using fluid dynamics modeling.