Meeting Abstract
60.2 Saturday, Jan. 5 Scaling properties of sunfish feeding muscles COUGHLIN, D.J.*; CARROLL, A. M.; AMBROSE, A. M.; ANDERSON, T. A .; Widener University, Chester, PA; Harvard University, Cambridge, MA; Widener University, Chester, PA; Widener University, Chester, PA djcoughlin@widener.edu
The physiological properties of vertebrate skeletal muscle typically show a scaling pattern of slower contractile properties with growth. In fishes, the myotomal or swimming muscle reportedly follows this pattern with slower muscle activation, relaxation and maximum shortening velocity (Vmax) with an increase in body size. We asked if the muscles involved in suction feeding by fishes would follow the same pattern. Specifically we focused on the cranial epaxial muscle, a muscle that elevates the cranium during fish feeding strikes and has been shown to power suction generation in sunfish. We hypothesized that feeding muscles in piscivorous fishes that feed on evasive prey are under selection to maintain high power output and therefore would not show slower contractile properties with growth. To test this, we compared contractile properties in feeding muscle (epaxial) and swimming muscle (red and white myotomal) for two members of the family Centrarchidae (sunfish): the planktivorous bluegill and the piscivorous largemouth bass. In particular, Vmax was determined for each muscle type, as well as activation and relaxation times in isometric contraction. Epaxial and white myotomal muscle in bluegill showed similar scaling properties- both muscles slowed with growth. However in bass, the epaxial muscle of larger fish had a significantly faster Vmax than white myotomal muscle of the same individuals. The results indicate that the piscivorous largemouth bass display different scaling patterns for their feeding vs. swimming musculature.
