Biological systems are known to be self organizing. In this talk I will present two specific examples of self organization in biological systems. The first part of the talk will highlight the idea of criticality in neuronal systems. I will present a mean field methodology towards expanding neuronal data sets in order to understand the criticality of neural networks. In the second part of the talk I will present a reaction diffusion model to describe the phenomenon of actin waves in Dictyostelium.