Annual Review of Condensed Matter Physics Physarum polycephalum: Smart Network Adaptation

Life evolved organisms to adapt dynamically to their environment and autonomously exhibit behaviors. Although complex behaviors in organisms are typically associated with the capability of neurons to process information, the unicellular organism Physarum polycephalum disabuses us by solving complex tasks despite being just a single although gigantic cell shaped into a mesmerizing tubular network. In Physarum, smart behaviors arise as network tubes grow or shrink due to the mechanochemical coupling of contractile tubes, fluid flows, and transport across the network. Here, from a physicist’s perspective, we introduce the biology and active chemomechanics of this living matter network. We review Physarum’s global response in migration and dynamic state to its environment before revisiting its network architecture and flow and transport patterns. Finally, we summarize recent studies on storing and processing information to mount well-informed behaviors.