Meeting Abstract

P2.73  Jan. 5  A Re-examination of the Decoupled Jaw Mechanism: Feeding Behavior in a Goby Cichlid, Eretmodus cyanostictus COLPITTS, Katie/M.*; O’NEILL, Matthew/W.; GIBB, Alice/C.; Mt. Holyoke College; Northern Arizona University; Northern Arizona University kmcolpit@mtholyoke.edu

Upper jaw (premaxilla) protrusion is thought to enhance feeding performance in teleosts (bony fishes) by enabling more effective prey capture. In most fishes, premaxillary protrusion is coupled to lower jaw depression. Liem (1979) proposed that the goby cichlid, Eretmodus cyanostictus, uses a mechanism in which the premaxilla moves independently from the lower jaw, and instead is correlated with neurocranial rotation. We tested this hypothesis by comparing the goby cichlid to Archocentrus nigrofasciatus (convict cichlid), using high speed digital imaging, and dissection and manipulation. For the goby cichlid, we found no correlation between premaxillary protrusion and neurocranial rotation. However, our results did support Liem�s suggestion that in the goby cichlid premaxillary protrusion is �decoupled� from lower jaw depression. While this decoupled mechanism may contribute to the diversity of the African cichlids, we note that South American cichlids with a �coupled� mechanism of premaxillary protrusion display a similar level of diversity in feeding behaviors.