How can an organism grow to form a desired structure and pattern? Understanding the morphogenesis of an organism, the collective self-organization of cells that gives rise to a functional structure is at the heart of decoding life. We aim to identify the rules of development by studying the physical principles underlying the formation and adaptation of biological organisms. Currently we investigate the mechanics of plant growth and the fluid dynamics enabling the slime mold Physarum polycephalum to adapt its network-like body to its environment. Our approach is combining both theoretical physics and experiments. On the theoretical side, we use analytical and numerical methods from mechanics, fluid dynamics, statistical physics and non-linear dynamics. On the experimental side, we investigate the adaptation dynamics of Physarum polycephalum with bright-field microscopy, transformations, micro-injection and tailored quantitative analysis.