Members of termite families may follow different developmental pathways to become part of various castes. Each caste has its own role within the family. Workers comprise the bulk of the population and are responsible for activities such as feeding all dependent castes, digging tunnels, and building and repairing the nest. Soldiers provide colony defense against predators. Queens, or primary reproductives, are relatively immobile and greatly depend upon the workers. The queen's mate, the king, also loyally attends her. Secondary reproductives will take over if a primary reproductive of the same sex dies. They sometimes have to wait a very long time, however, since termite queens have been known to live for over ten years and some mounds indicate longevity of forty years.