Fig. 8.

In the rare Arctic species P. cyrtoptera, flagella can remain at rest for seconds in a stand gait (A and B). One such cell, where all 16 flagella are visible, is shown in B. Cells appear yellow-green and lobed (C). (D) Pronking involving all 16 flagella (Movie S8) is a common swimming gait. The cell body is tracked along a typical trajectory and colored by normalized phase ${\varphi }_{16}$ (colorbar), computed from the area $\mathcal{A}\left(t\right)$ bounding the flagella that expands and contracts according to the periodicity of flagellar beating (shown here at four representative phases). (Inset) Time series of $\mathcal{A}$ over six successive cycles. (Scale bar: 20 μm.)