Figure 1.

Ultrafast time series of contracting Vorticella convallaria. (A) Sequential images (millisecond timescale) of contraction in water. Contraction begins at the base of the zooid (0 ms) and propagates along the stalk toward the substratum. Scale bar = 50 μm (see Movie S1). (B) A simplified model of contracting V. convallaria. The sphere of radius R representing the shrunken zooid moves at the contraction velocity U_c perpendicularly toward the rigid plane representing the substrate. L_s is the stalk end-to-end length.