Emergent Run-and-Tumble Behavior in a Simple Model of Chlamydomonas with Intrinsic Noise

TL;DR

This paper demonstrates that a simple hydrodynamic model with noise can produce run-and-tumble behavior in Chlamydomonas, suggesting a mechanical basis for this movement pattern without complex biochemical control.

Contribution

It introduces a minimal hydrodynamic model with intrinsic noise that reproduces run-and-tumble behavior, highlighting nonlinear mechanics as a potential control mechanism.

Findings

Run-and-tumble behavior emerges from the model due to nonlinearity.

Intrinsic Gaussian white noise induces stochastic switching.

The model suggests mechanical control of movement in algae.

Abstract

Recent experiments on the green alga Chlamydomonas that swims using synchronized beating of a pair of flagella have revealed that it exhibits a run-and-tumble behavior similar to that of bacteria such as E. Coli. Using a simple purely hydrodynamic model that incorporates a stroke cycle and an intrinsic Gaussian white noise, we show that a stochastic run-and-tumble behavior could emerge, due to the nonlinearity of the combined synchronization-rotation-translation dynamics. This suggests the intriguing possibility that the alga might exploit nonlinear mechanics---as opposed to sophisticated biochemical circuitry as used by bacteria---to control its behavior.