Meeting Abstract
In ray-finned fishes, the sternohyoid (SH) is amongst the largest of the cranial muscles and from its size should contribute to the overall power required for suction feeding. In largemouth bass (Micropterus salmoides) however, the SH makes little to no power contribution as it does not shorten during suction expansion, a requirement for power production. The SH muscle in largemouth bass is relatively small, representing less than 2% of the cranial and axial muscle mass responsible for producing necessary power. For comparison with largemouth bass, we studied a single species, the striped surfperch (Embiotoca lateralis), in which the SH is 8% of the active muscle mass, to determine the possibility SH contribution to suction power. We measured muscle strain in the SH, epaxial, and hypaxial muscles with external markers attached to the skin, as the skin is tightly connected to the underlying muscles. Suction feeding was recorded with two high speed video cameras (500-1000 frames/s) calibrated with a Lego calibration object. We tracked the markers and calculated 3D coordinates with XMALab software (n=18 strikes from 3 individuals). We found that the SH shortened by a mean of 9.5% during suction expansion in the striped surfperch. The mean peak velocity of shortening was 5.4 lengths/sec, which is near the optimal velocity for power production in fish white muscle. We conclude that the sternohyoid is not only capable, but also likely to contribute to overall expansion power in Embiotoca lateralis, though further study is necessary to determine to what extent.
