Sessile suspension feeders live attached to surfaces and rely on self-generated feeding currents to bring in suspended prey. A new study published in Journal of the Royal Society Interface combines experiments on the sessile ciliate Vorticella convallaria and fluid dynamical calculations to quantify the influence of ambient flows on the clearance rates of such microorganisms.
We find that feeding flows and clearance rates are profoundly different for organisms in ambient flow, their natural state, compared to previous results, nearly all of which were obtained in still water. We observe that even very slow ambient flow disrupts the eddies around perpendicular suspension feeders, providing them with a constant supply of food-rich water. However, we show that ambient flow in general may either help or counter the feeding current and prevent or intensify recirculation depending on the ability of the organism to adjust its orientation, and on whether it drives the water away from or towards the surface. The feeding flows also bring nutrients and particles to the attachment surfaces. Thus, our results have implications for larger-scale system processes, whether it is productivity of seagrasses or the formation of rapidly sinking marine snow aggregates that help sequester carbon in the ocean.
Read the paper here: https://royalsocietypublishing.org/doi/10.1098/rsif.2020.0953
Pepper RE, Riley EE, Baron M, Hurot T, Nielsen LT, Koehl MAR, Kiørboe T, Andersen A (2021) The effect of external flow on the feeding currents of sessile microorganisms, Journal of the Royal Society Interface 18, 20200953.
Header image: The sessile ciliate Vorticella convallaria and observed flow around an individual of V. convallaria on a flat surface in an ambient flow from left to right.