Collaborative Research: Scaling of Unsteady Locomotor Performance and Maneuverability

Saint Louis University, Saint Louis MO

Investigators

Abstract

Whales, the largest animals, must be able to maneuver in their aquatic environment to capture prey, avoid predators, navigate complex environments, and compete for mates. The ability to maneuver (e.g., accelerate, turn quickly and tightly) generally decreases as mass increases, suggesting there is an upper size limit for maneuvering aquatic animals. This study will evaluate the size dependence of maneuverability of the largest animals in the ocean, rorqual whales, performing natural behaviors in the wild. Custom-designed removable sensors placed on the bodies of free-ranging whales will record their movement while aerial drones with specialized cameras will measure the size and shape of the whales and their appendages (i.e., flippers, flukes) at the surface of the water. By combining these data with mathematical modeling of hydrodynamic forces, different sized whale species can be compared to determine mechanical constraints imposed by size as a driving force in the ecology and evolution of the world?s largest predators. This project will include the training of graduate students and postdoctoral scholars in interdisciplinary research that integrates engineering and physics with biology. Further, the results may provide insights into the biomimetic design of autonomous underwater vehicles with enhanced maneuvering performance. Movement is a fundamental aspect of animal life. Quantifying the fine-scale movement of individuals has important consequences for understanding physiological, ecological, and evolutionary processes. Maneuvering capacity is also critically important as it governs an animal's ability to capture prey, avoid predators and obstacles, inhabit complex environments, and compete for mates. Investigations into how animals maneuver in aquatic environments remains poorly understood, particularly for large animals at the extreme of animal body mass. This proposal develops a bio-logging and remote sensing approach, with computational modeling, to analyze the kinematics and maneuverability of free-ranging rorqual whales (Balaenopteridae) ranging in body mass by an order of magnitude. Swimming performance (i.e., acceleration: change in swimming velocity; agility: rate of turning; maneuverability: turning radius) will decrease as body size increases across rorqual species and that these mechanical constraints imposed by morphology size will be evident as a driving force in the ecology and evolution of the world's largest predators. Custom engineered multi-sensor animal-borne tags and Fluid Lensing cameras attached to aerial drones will be used to analyze the kinematics and morphology of rorquals in the open ocean. This approach enables us to quantify the high-resolution kinematics of rorquals engaged in natural maneuvers while simultaneously quantifying the morphological dimensions of tagged animal, including control and propulsion surfaces. By combining these data with modeling where hydrodynamic forces can be calculated via Computational Fluid Dynamics (CFD) and trajectories