Complex life above a certain size would not be possible without a circulatory system. Both plants and animals have developed vascular systems of striking complexity to solve the problem of nutrient delivery, waste removal, and information exchange. Vascular networks are intimately linked to the fitness of organisms. Despite their importance, the principles that govern the structure, topology, function, development and evolution of biological flow networks are not well understood.

In this talk we present how a biological transport network can utilise principles of self organization to develop and function. We first discuss how a hierarchically organized vascular system can develop  under constant or variable flow and show how time-dependent flow can stabilize anastomoses and lead to a topology dominated by cycles. Next, inspired by haemodynamic fluctuations in the brain, we examine how networks can produce self-sustained oscillations in the flow even in the absence of varying external input. We discuss how these spontaneously emerging, self-organized fluctuations depend on the network topology, and how they can be modified by a controlled external input.