Swimming Pattern of \textit{Vorticella convallaria} Trophont in the Hele-Shaw Confinements

In the trophont form \textit{Vorticella convallaria }is a sessile stalked ciliate, which consists of an inverted bell-shaped cell body (zooid) and a slender stalk attaching the zooid to a substrate. Under mechanical shearing, the zooid is separated from the stalk and can swim using circular cilia rows around the oral part. Here we present how the stalkless trophont zooid of \textit{V. convallaria }swims in Hele-Shaw geometries, as a model system for microorganism swimming. After having harvested stalkless zooids, we observed their swimming in water between two glass surfaces with narrow gaps using video microscopy. Based on their swimming trajectories measured with image analysis, we investigated how the swimming pattern of the trophont zooid of \textit{V. convallaria} was influenced by the constraints.