Flagellates live in a small-scale environment where viscosity impedes contact with their bacterial prey. Most flagellates use the active waving motion of a flexible flagellum with hairs to generate a feeding current. The presence of hairs significantly increases the force generated by the flagellum and also reverses its direction, hence producing an efficient feeding current coming towards the flagellate. A recent paper from the Centre describes the underlying mechanism of the force production in hairy flagellates.
Predatory flagellates are important in aquatic food webs and the marine carbon cycle, and their survival relies on the feeding flow generated by their hairy flagellum. We have revealed a mechanism for thrust generation in flagellates with hairy flagella, which is fundamentally different from the slender body theory governing smooth flagella. We show that the thrust is generated at the crests of the flagellar wave, thanks to the key role of hydrodynamic interactions among hairs that therefore effectively function like a flexible sheet. The mechanism suggests that the optimal hairy flagellum should have short wavelength and be strongly curved. This and other predictions are consistent with the diverse designs of hairy flagella observed in nature.
Read the paper here:
https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.7.073101
Asadzadeh SS, Walther JH, Andersen A, Kiørboe T. Hydrodynamic interactions are key in thrust-generation of hairy flagella, Physical Review Fluids, 7, 073101 (2022)
DOI: 10.1103/PhysRevFluids.7.073101