Meeting Abstract

79.2  Sunday, Jan. 6  Using sonomicrometry to compare pharyngeal jaw kinematics in cypriniform fishes RADE, CM*; SANFORD, CP; HERNANDEZ, LP; George Washington Univ; Hofstra Univ; George Washington Univ cristinarade@gmail.com

While much of the documented functional diversity in fish feeding systems involves the mechanics of suction feeding and prey capture, the pharyngeal jaw apparatus (PJA) is an understudied element of fish trophic diversity. The PJA is a second set of jaws behind the gill arches that serves to separate organic and inorganic matter, manipulate prey, and process food items. These jaws promote trophic diversity by decoupling feeding and processing events, thus providing an opportunity for different prey types. Cypriniformes is a diverse clade of teleosts characterized by a novel PJA that has significantly hypertrophied ceratobranchials 5 and a loss of the upper pharyngeal jaws, a feature seen only at the base of this group. Here we examine the use of the cypriniform PJA during prey handling in two species by employing sonomicrometry to interpret the kinematics of this novel biomechanical system. Using the positional relationships of five piezoelectric crystals we monitored the movements of the lower pharyngeal jaw in transverse and sagittal planes for goldfish (Carassius auratus) and sailfin suckers (Myxocyprinus asiaticus) to account for phylogenetic and behavioral differences, with goldfish being a member of Cyprinoidea and sailfins representing the other major clade, Cobitoidea. Goldfish predominantly use the pharyngeal jaws for crushing and grinding, while catostomids presumably use these jaws for sifting purposes. M. asiaticus is especially important for understanding functional difference within this group as there is no published functional work on catostomid fishes to date. Statistical analyses reveal that the catostomid generates more chewing cycles per event and less lateral movement in the transverse plane than the cyprinid species.