Cineradiographic analysis of the pharyngeal jaw movements during feeding in Haplochromis burtoni (Pisces; Cichlidae).

Analysis of lateral radiographic films reveals that the upper and lower pharyngeal jaws in Haplochromis burtoni (GUNTHER, 1893) show opposite anteroposterior displacments during food reduction. Force is generated during upper jaw retraction by elevation and slight protraction of the lower pharyngeal jaw (compression phase) and subsequently by depression and strong protraction of the lower jaw (shearing phase). These results contradict previous findings in which the upper and lower pharyngeal jaws show synchronous protraction and retraction.