DURIE, Christopher J.; University of Rhode Island: Opercular-linkage disruption: a test of the four-bar linkage model

The kinematics of prey-capture in blackchin tilapia (Sarotherodon melanotheron) subjected to three experimental treatments (control, anesthetization, and linkage-disruption) were analyzed using high-speed video to explore the role of the opercular four-bar linkage in opening the mouth in teleost fishes. A series of two-way mixed model analysis of variance (random effects = fish; fixed effects = treatment) revealed that maximum gape, lower jaw angle, gape cycle, and time to lower jaw depression differed among treatments. Gape and lower jaw angle appeared to be greater in the control and anesthetized treatments than in the linkage-disruption treatment. While gape cycle and time to lower jaw depression took longer to occur in the linkage-disruption treatment than in the other two treatments. Tukey post-hoc comparisons revealed that the linkage-disruption treatment differed from the control and anesthetization treatments suggesting that severing the opercular linkage affected the ability of fish to depress the lower jaw. Severance of the opercular linkage did not affect the ability of fish to detect, approach and capture prey. We hypothesize that although the opercular four-bar linkage system may not be the only linkage mechanism involved in depressing the lower jaw, it still plays a very important role in opening the mouth during feeding in teleost fishes by allowing a more rapid and controlled feeding event.