  In this fluid dynamics video we investigate the flow field around
straight-line swimming and right and left turning Paramecia using micro-
particle image velocimetry ({\mu}PIV). A Paramecium controls its ciliary
beating to produce different fluid velocities on either side of its body. This
phenomenon is visualized by applying {\mu}PIV to images in which Paramecia swim
in a dilute suspension of 1 {\mu}m polystyrene spheres. Paramecia that swim
straight exhibit similar magnitudes of velocity on either side of their bodies.
In contrast, right-turning Paramecia exhibit greater magnitudes of velocity on
their right sides, while left-turning organisms show the opposite.
