The ability to take relevant kinematic and physiological measurements of animals is key for their understanding.

Without measurements, it is not possible to make inferences about their biomechanics and physiology.

Cetaceans — compromising dolphins, whales, and porpoises — are especially difficult to study due to their ecological niche.

Oceans are vast, the water limits visibility and attenuates radio transmissions, and accessing wild populations is logistically difficult.

Experimental measurements thus of their swimming behavior has proven difficult.

Recent advances in biologging tags have allowed for a greater variety of collected data:​ hydrophones for collecting acoustic data, GPS for estimated position, calibrated impellers for speed, and inertial measurement units (IMUs) for orientation, and electrodes for electrocardiograms (ECGs) to estimate heart rate. These new data streams have all contributed to expanding our understanding of dolphins and other cetaceans. However, typical deployments of such tags involve the placement of only one such device on an animal, providing measurements at only a single-point. In the context of swimming energetics, overall dynamic body acceleration (ODBA) as measured by an IMU or applying Newton's Second Law to the change in speed have served to estimate costs of transport or thrust production. Such models and measurements though do not provide any knowledge of the entire body, simplifying the motion of the body needed to drive the fluke (tail fin) through the water to the motion of the center of mass (COM). On the other end of complexity, computational fluid dynamics (CFD) simulations have been recently applied to the swimming of dolphins, utilizing kinematic data from cameras. Such methods require clear visibility of the swimming dolphins, a non-trivial feat due to the limited field of view of cameras, dolphin training that is required, and the computational complexity of such models. These types of simulations tend to be limited in the variation in parameters and speeds.

To address full-body kinematics, new smaller tags were designed that can be attached using suction cups down the length of the animal. These were deployed during swimming trials to investigate the swimming kinematics of multiple dolphins across a range of speeds. These served as inspiration for an aerospace-inspired sagittal-plane hydrodynamic model of dolphin swimming. The dolphin body is abstracted as four linked rigid bodies forming the head, torso, anterior peduncle, and posterior peduncle, to which a flexible fluke is attached via a torsional spring. This model is compared with existing literature and the kinematic measurements. This model then serves as the basis for an exploration of fluke shapes and their impact on the costs of transport (COT). To investigate the impact of body kinematics, the model is used to estimate internal torques, internal power, and energetic costs.

Finally, to extend physiological measurements, we perform a first-of-their-kind near-infrared spectroscopy (NIRS) measurements in free-swimming dolphins using a custom tag. This data is sampled concurrently with kinematic data for COM dynamics, allowing for new future experimental paradigms to study cetacean respiratory physiology.