Stochastic Analysis of Taxis and Kinesis Properties of Colonial Protozoa

by Yonatan L. Ashenafi & Peter R. Kramer

This study asks whether cells that navigate well alone can still find oxygen or food after joining a colony. Using a choanoflagellate-inspired mathematical model, it shows that colony life can completely change the rules: a steering-based strategy (taxis) that works for single cells can break down collectively, with competing forces even pushing the colony the wrong way. By contrast, a noise-tuning strategy (kinesis) stays remarkably effective, allowing colonies to keep climbing gradients even under adversarial flagellar arrangements. The work shows how reliable collective motion can emerge from noisy, imperfect parts and offers design ideas for simple adaptive microrobotic swarms.

Schematic of the taxis and kinesis flagellar-response models for cells within a colony in the presence of an environmental gradient (blue arrows). Left: Colony of taxis-enabled cells. The red arrow indicates the biased flagellar force direction that would generate a torque tending to rotate the cell so that it swims up the environmental gradient. Right: Colony of kinesis-enabled cells. The red wedge indicates the estimated range of motion of the beating flagellum.