The defender was a type of bioship in use by Species 8472 in the 24th century. These vessels are not combatants, but rather created strategic defenses through a spawning process. The defenders could create the Species 8472 sentinel, which was a type of biological space station that functioned as a defense weapon turret. These vessels could also lay Species 8472 mines, which were living explosives that acted much like conventional technological mine weapons.