Flow Characteristics of Chlamydomonas result in Purely Hydrodynamic Scattering

TL;DR

This study demonstrates that the scattering behavior of Chlamydomonas near surfaces can be explained solely by hydrodynamic interactions, challenging the previous belief that mechanical contact is necessary for boundary sensing.

Contribution

The paper introduces a model swimmer with a flow field similar to Chlamydomonas, showing boundary scattering is purely hydrodynamic without flagellar contact.

Findings

Scattering from walls can be explained by hydrodynamics alone.

Flagellar contact is not necessary for boundary sensing.

Hydrodynamic interactions govern boundary escape behavior.

Abstract

It has long been believed that swimming eukaryotes feel solid boundaries through direct ciliary contact. Specifically, based on observations of behavior of green alga Chlamydomonas reinhardtii it has been reported that it is their "flagella [that] prevent the cell body from touching the surface" [Kantsler et al. PNAS, 2013]. Here, via investigation of a model swimmer whose flow field closely resembles that of C. reinhardtii, we show that the scattering from a wall can be purely hydrodynamic and that no mechanical/flagellar force is needed for sensing and escaping the boundary.