Motility of Colonial Choanoflagellates and the Statistics of Aggregate Random Walkers

TL;DR

This paper investigates the three-dimensional random walk behavior of colonial choanoflagellates, revealing that their stochastic flagellar beating results in helical swimming patterns, with a quantitative theory explaining species variability.

Contribution

It provides the first detailed analysis of aggregate random walkers in microorganisms, linking stochastic flagellar motion to their swimming behavior and developing a quantitative model.

Findings

Flagellar beating is stochastic and uncorrelated among individuals.

The combined propulsion results in stochastic helical swimming.

A quantitative theory explains variability across species.

Abstract

We illuminate the nature of the three-dimensional random walks of microorganisms composed of individual organisms adhered together. Such $aggregate~random~walkers$ are typified by choanoflagellates, eukaryotes that are the closest living relatives of animals. In the colony-forming species $Salpingoeca~rosetta$ we show that the beating of each flagellum is stochastic and uncorrelated with others, and the vectorial sum of the flagellar propulsion manifests as stochastic helical swimming. A quantitative theory for these results is presented and species variability discussed.