Trophic morphology, feeding performance and prey use in the polymorphic fish Herichthys minckleyi

Question: How does pharyngeal jaw morphology influence feeding performance and prey use in the trophically polymorphic cichlid fish Herichthys minckleyi ? Organism: Herichthys minckleyi exhibits two discrete pharyngeal jaw morphologies. Molariforms possess flattened teeth and enlarged pharyngeal muscles, whereas papilliforms exhibit more gracile jaws, pointed teeth and smaller muscles. Data: We combined anatomy, experiments, diet analyses and a review of molluscivory to examine the relationships between morphology, feeding performance and prey use. Conclusions: Handling time differed only slightly between morphotypes. Papilliforms shredded plants more finely than molariforms, and only molariforms readily crushed snails. Molariforms employed their maximum force-producing capabilities to crush snails in the wild. Comparisons with other molluscivorous fish suggested that the amount of hard-shelled prey molariform H. minckleyi ingest is not unusual, but its pharyngeal muscle mass and the force used to crush snails are extreme.