The feeding on suspended food particles in ciliates is complex and relies typically on coordinated motion in bands of transversal rows of cilia known as membranelles. A new paper in Physical Review Fluids explores and models the fluid dynamics of feeding flow and particle retention in ciliates that use a single membranelle band to both generate feeding flow, retain food particles, and transport them to the cell mouth.
Ciliates are ubiquitous in the marine environment and important consumers of phytoplankton and flagellates. Many ciliates use a single membranelle band for feeding, and to mechanistically understand this feeding mode, we explore the ciliate Euplotes vannus. The cilia move parallel to the membranelle band towards the mouth region in the power strokes, and a metachronal wave propagates away from the mouth region parallel to the band and outwards along the membranelles. A gap therefore opens between neighboring membranelles from the inner side of the band where the mouth region is located, and while food particles are retained, water is drawn in and pushed outwards across the membranelle band as the gap closes from the inner side. We propose a model that rationalizes our observations and suggests a trade-off between the clearance rate and the membranelle gap that determines the lower cut-off in the prey size spectrum.
Read the paper here: https://doi.org/10.1103/PhysRevFluids.7.023102
Rode M, Kiørboe T, Andersen A (2022) Feeding flow and membranelle filtration in ciliates, Physical Review Fluids 7, 023102 (2022).
Header image: Micrograph of the ciliate Euplotes vannus with flow sketch (left) and particle tracks visualizing the feeding flow along and through the membranelle band (right).