Fig. 1. (A,B) Bluegill sunfish Lepomis macrochirus, hovering in still water, and (C) snowy grouper Epinephelus niveatus skeleton, showing the positions of the major fins and their internal skeletal supports. The pectoral and pelvic fins are paired, while the dorsal, anal and caudal fins are median (midline) fins. The dorsal and anal fins of ray-finned fishes have internal skeletal supports (pterygiophores), which support musculature that moves the fin rays. Fin rays are labeled in yellow for the dorsal and anal fins. The caudal fin also has a complex series of intrinsic musculature that allows fishes to actively control tail conformation (Drucker and Lauder, 2001; Lauder, 1982; Lauder, 1989). Metal supporting elements for the grouper skeleton have been digitally removed for clarity.