Confinement and hydraulic resistance appear to separately govern motility and path selection in Physarum polycephalum

Abstract In self-organizing biological systems, structure often emerges from the interplay between physical constraints and active behaviours. We explore this principle in the unicellular slime mould Physarum polycephalum, focusing on how it selects growth paths and modulates movement under geometric confinement. Using microfluidic devices with bifurcating channels of varying lengths and hydraulic resistances, we demonstrate that Physarum consistently favours the path of least hydraulic resistan