In this thesis, we present our work aiming at tracking and studying the swimming behavior of Paramecium, a unicellular eukaryotic microorganism, in a free environment over long time scales, reminiscent of the run-and-tumble motion of some flagellated bacteria, as it consists of long runs interrupted by shorter reorientation events. To achieve this, we started to develop an automatic tracking system using a translational stage mounted on a microscope. We recorded and analyzed the trajectories of four Paramecia tracked for different time durations and extrapolated mean velocity, mean square displacement and avoiding reactions frequency from the data. Lastly, we briefly discuss how - by analysing more trajectories and changing the physical and natural conditions of the observations - a better understanding of Paramecium dynamics can be achieved..