Motility of Colonial Choanoflagellates and the Statistics of Aggregate Random Walkers

Abstract

We illuminate the nature of the three-dimensional random walks of microorganisms composed of individual organisms adhered together. Such $aggregaterandomwalkers$ are typified by choanoflagellates, eukaryotes that are the closest living relatives of animals. In the colony-forming species $Salpingoecarosetta$ 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.

5 pages, 4 figures, supplementary information included (2 videos available at website of R.E.G.); in press at Physical Review Letters