A linear actuator includes a substantially cylindrical magnetostrictive element disposed in a housing. A retainer is cooperatively engaged with the housing and an exterior of the magnetostrictive element such that relaxed portions of the magnetostrictive element are frictionally retained in the retainer. An actuator rod is functionally coupled to one longitudinal end of the magnetostrictive element. A biasing device is disposed between the housing and the retainer to maintain the retainer in lateral compression. The actuator includes magnets arranged to induce peristaltic motion in the magnetostrictive element.