Paramecia swimming in viscous flow

Abstract

Waves propagating in confi ned geometries usually evolve into spatially stationary patterns, built from the interference between the waves that have been refl ected upon hitting the boundaries. However, a recent study on bio-locomotion [1] has reported that traveling wave kinematics can naturally emerge in a forced elastic rod, even with boundary conditions involving signifi cant refl ections. It has been shown that this particular behavior is observed only in the presence of strong damping. Based on those observations, we aim at giving a quantitative description of the mechanism involved to prevent the built-up of standing waves and establish traveling fi sh-like kinematics (that optimizes the global swimming effi ciency). The question is discussed here in the framework of hand-made artifi cial swimmers as an example of practical application.

Axisymmetric spheroidal squirmers and self-diffusiophoretic particles

“…Volvox [12], observed in experiments, its restriction to spherical swimmers limits a wider application. For example, Paramecia, one of the most studied ciliates, has an elongated body [13][14][15], which prevents a straightforward application of the traditional squirmer model. However, the aforementioned questions are also of interest for these and other elongated micro-organisms.…”

Universal entrainment mechanism controls contact times with motile cells

“…These include fundamental processes like nutrient uptake [24][25][26][27][28][29][30][31]; viral and fungal infection of microorganisms of ecological and commercial importance [32][33][34], eukaryotic fertilisation [35]; and grazing, which happens on natural preys [30,[36][37][38] as well as marine microplastics [39,40], and is recently being discovered as a fundamental behaviour in many strains of motile green algae until recently regarded as exclusive phototrophs [34,41,42]. With the exception of complex feeding currents in ciliates like Vorticella [43,44] or Paramecium [45,46], the window of opportunity for these microbial interactions to take place will depend on a finite contact time T . For a constant success rate per unit time Ω, the probability that the interaction is successful is given by p(T ) = 1 − e −ΩT [38].…”

Dynamics of animal systems

“…Bookending the section with the locomotion in micro-organisms, Zhang et al [30] investigate the energetic benefit on the Paramecium locomotion from its body asymmetry. The authors combine particle image velocimetry and the boundary element method to develop a model of the fluid motion around a swimming Paramecium.…”