Many efforts have been done towards secure MANETs, but the conventional lines of defense are still inefficient to put all attacks off. This article examines survivable approaches whose goal is to enable networks to fulfill correctly their critical functions even in the presence of attacks or intrusions. We introduce the most relevant survivable MANET initiatives where either preventive or reactive defenses are combined with tolerant ones. We classify the defense lines taking into account intrusion tolerance mechanisms and also identify properties and requirements of survivability. The initiatives are categorized in three groups: routing discovery, data transmission and key management. For each one, they are correlated in terms of requirements and properties. The survey shows that security solutions do not yet explore relevant survivability properties and have only focused on one network layer or one type of attack.