Meeting Abstract
Bauplans typical of aquatic vertebrates create intrinsic hydrostatic and hydrodynamic destabilizing forces and torques. Reliance on oscillatory propulsors creates additional intrinsic instabilities. These instabilities are continuously corrected by trimming and powered control forces and torques, which can be energetically costly. Intrinsic instabilities have arisen over evolutionary time and various associated adaptations have been postulated to reduce the magnitude and impact of perturbations. The largest perturbing forces and torques arise from body/caudal fin propulsion, for which anatomy and morphology of propulsors and other body parts damp, correct or cancel disturbances. Future challenges to understanding the challenges and solutions for stability in aquatic vertebrates include methods for repeatable experiments, probably at stability limits. Traditional comparative approaches will be insufficient. Biomimetic robotic models with fish-like motions will be essential, especially to explore stability through control of trailing edge shape and motions. An emergent feature of oscillatory propulsors is whole-body accelerations that can be recorded in free-living animals. While such accelerometry cannot determine power consumption for locomotion by free-living aquatic animals, patterns correlating with various behaviors may provide a basis for constructing ethograms. In terms of extrinsic perturbations, fishes are readily able to detect, respond and use local flow unsteadiness. It remains unknown if or how well fishes can anticipate and negotiate flow fields to minimize transport costs as postulated for some migrants.
