Maneuverability in the marine environment requires a degree of controlled instability. Cetaceans move by dorso-ventral oscillation of their trunk and caudal flukes and have body designs that allow for efficient, stable, and steady swimming. To maneuver during behaviors like prey capture, their control surfaces (i.e. fluke, flipper, dorsal fin) are used to create controlled instabilities. The morphology of cetacean control surfaces is ecologically important as they constrain hydrodynamic performance, and subsequently influence the ability of cetaceans to execute different feeding strategies. To gain insight into evolutionary patterns of morphological variability in whales that use different feeding strategies, and to help understand the hydrodynamics of foraging, we are analyzing control surface morphology across the cetacean phylogeny. Our initial investigations have focused on the relationships amongst control surface size, shape, and body size of three mysticete species: humpback, blue, and minke whales. Using high resolution photographs of planiform control surfaces of multiple individuals, we measured characteristics of the fluke, flipper, and caudal peduncle using the MorphoMetriX software package. We regressed these metrics on body length to understand scaling differences amongst species. Preliminary results indicate that the slope and intercept of control surface metrics vary amongst mysticete species, with some control surface metrics showing isometry. Differences in size and shape of control surfaces among these species may suggest they are using these surfaces differently to harness controlled instability and facilitate maneuvers.