In this paper, we describe an approach to artificial life, which uses Qualitative Reasoning for the simulation of life within a 3D virtual environment. This system uses qualitative formalisms to describe both the physiology of a virtual creature and its environment. This approach has two main advantages: the possibility of representing integrated physiological s at various levels of abstraction and the use of a common formalism for the simulation of internal (physiological) and external (environmental) processes. We illustrate this framework by revisiting early work in Artificial Life and providing these virtual life forms with a corresponding physiology, to obtain a complete living organism in virtual worlds.