Abstract

Microscale propulsion requires adaptation of swimming strategies to the limitations of Stokes flow. Within the host of unicellular microorganisms, myriads of different forms and functions are exploited to achieve swimming. This richness of behaviour has inspired three research stories. In the first tale, we have collected data from the available literature on swimming eukaryotes and explore the statistical variability of their swimming speed. A careful examination of the statistical properties of the speed distribution for both flagellates and ciliates shows that they are not only both captured by lognormal distributions but that, upon rescaling the data by the average swimming speed for each data set, the speed distributions in both types of organisms are almost identical. In the second tale, our data for ciliates are useful to deduce whether their cilia beat at a constant force, or rather operate at a constant stress. In the last story of tails, we look at a biomimetic system of thin elastic filaments extruded into the fluid and observe their dynamic buckling and folding, which gives an insight into their elastic properties.