Dynamic behavior is inherent in virtual organizations. Semantics has to be processed to manage dynamism and other properties like state, life cycle, faults, and others. In our paper we identify a gap between service interfaces and semantic for dynamic services to establish virtual organizations. We propose a novel approach called "Dynamic Service Evolution" (DSE) to overcome this gap. A common language is needed to allow dynamic semantic information processing. The evolution of a language enables bilateral agreements between services and clients in an open process. We have applied our approach in N2Grid and present a prototype in this paper. N2Grid deploys artificial neural networks as virtual resources in a Grid. By the DSE we solve the problem, that no general standards (languages) for neural network representations exist.