Thanks to recent advances in robotics, sensors and wireless communications, it is feasible to develop a variety of new architectures for Mobile Wireless Sensor Networks (MWSNs) that play an important role in various applications such as battlefield surveillance, harbor monitoring, etc. However, due to the dynamic of mobile network topology in MWSNs, many new security challenges have emerged. In this article, we give a survey on the state of the art technologies in security aspects of MWSNs. We review existing work that provides security in MWSNs, with an emphasis on data survival, forward secrecy, backward secrecy, authentication, and methods for sensor capture detection. Furthermore, in order to stimulate the exploration of new research areas, we point out a few open research topics that can be further pursued, and also shed light on these topics.