Colonies typically have three different termite castes: reproductives (including kings, queens, and primary and secondary reproductives), soldiers and workers.
Within these termite castes, the soldier is responsible for defending the nest. A termite’s main enemy is an ant. In most species, termite soldiers have strong jaws used to defend the colony against invaders. In some species, termite soldiers have a tube-like projection (called a fontanelle) that contains a sticky substance that entraps their enemies.
Soldier Termite: Notice the large dark mandibles
Sometimes, soldiers can use their large heads to block holes in tunnel walls until worker termites can repair the holes.
Scientists have filmed termites that communicate by banging their heads against tunnel walls. Termites use these vibrations to alert termite soldiers about invaders or tunnels that need to be repaired.
Soldier termites rely on worker termites to feed them. Soldiers cannot feed themselves because their large mandibles (jaws) prevent them from biting wood or other cellulose materials.
Soldier Termite on Piece of Wood