Travelling Wave

The fungus Rhizophagus irregularis grows as a network of thin tubes (hyphae) that self-organizes through a negative feedback loop. At low density, branching dominates and the network expands. At high density, tips fuse with existing hyphae (anastomosis), eliminating tips and creating transport loops. The result is a travelling wave: an advancing front of sparse explorer hyphae with a densifying rear of efficient loops.