Meeting Abstract

75.1  Saturday, Jan. 5  Functional morphology of ventilation in four species of sculpins (Scorpaeniformes) FARINA, SC*; FERRY, LA; Cornell University; Arizona State University

Fish move water over the gill tissue using pumps in both the buccal and opercular chambers. The pump in the opercular chamber consists of the opercular bones, or the gill cover, and a branchiostegal membrane supported by branchiostegal rays, which are long, slender bones articulating with the hyoid arch. Pelagic fishes tend to have relatively larger opercular bones and benthic fishes tend to have relatively larger branchiostegal membranes. This variation implies that there are important ecological and functional consequences of different opercular pump morphologies. Among four closely related scorpaeniform fishes (Myoxocephalus polyacanthocephalus, Hemilepidotus hemilepidotus, Leptocottus armatus, and Dasycottus setiger), we observed a continuum ranging from a large operculum (e.g., M. polyacanthus) to a large branchiostegal membrane (e.g., D. setiger). We obtained bi-planar video and simultaneous pressure transducer recordings in the buccal and opercular chambers, as well as maximum volumes of the chambers and the surface areas of the opercular bones and the branchiostegal membrane. Our goal was to determine which was most predictive of functional variation: differences in relative surface areas of operculum and branchiostegal membrane or differences in relative volumes of the buccal and opercular chambers. We found that the relative surface area of the operculum and branchiostegal membrane explained more of the variation in ventilation mechanics than did the relative volumes of the buccal and opercular chambers. These data suggest that ventilation biomechanics depend more on the morphology of the pumps driving the ventilatory current rather than the volume to which the chambers can expand.