Ethology and rheology of an amoeboid cell

We will show that ability of information processing in an amoeboid organism is higher than we had thought. The model organism is the plasmodium of Physarum polycephalum (true slime mold), which is a large aggregate of protoplasm with many nuclei. The organism found the optimal path when it obtained the multiple locations of food. A simple mathematical model for the path finding was proposed in terms of differential equations. As well as the path-finding ability, the organism was able to anticipate the next timing of periodic climate change after experienced some periodic changes of climate, and to show a kind of behaviors that seemed to be ‘ indicisive ’when it encountered the presence of a chemical repellent, quinine. We indicated that simple dynamics was enough to reproduce these observed behaviors. Mathematical modeling is helpful to understand the mechanism of behavioral smartness in slime mold. The behavioral smartness can be based on motion of viscoelastic body, so we discuss rheological description of smart behavior.