The Biomechanical Energetics of Terrestrial Locomotion in California Sea Lions (Zalophus californianus): Efficiency of Quadrupedal Galloping

• Main Author: Kerr, Sarah
• Format: Text
• Language: unknown
• Published: Digital Commons @ West Chester University 2021
• Subjects: Biomechanics; galloping; energetics; California sea lion; pinniped; locomotion; Marine Biology; Elephant Seal; harbor seal
• Online Access: https://digitalcommons.wcupa.edu/all_theses/208; https://digitalcommons.wcupa.edu/cgi/viewcontent.cgi?article=1294&context=all_theses

Pinnipedia, an order of semi-aquatic marine mammals, adapted a body design that allows for efficient aquatic locomotion but limited terrestrial locomotion. Phocids (true seals) have reduced forelimbs and are unable to bring their hindlimbs beneath them during terrestrial locomotion. Otariids, like the California sea lion (Zalophus californianus), have enlarged forelimbs and can bring their hindlimbs under the body to locomote quadrupedally on land. Due to these differences, phocids are expected to move on land with greater energetic costs compared to otariids. The mechanical costs of transport and power outputs of terrestrial locomotion were compared between the California sea lion and three phocid species (harbor seal, gray seal, and Northern elephant seal). One male and two female adult California sea lions were video recorded galloping across a level runway. The center of mass, along with six other anatomical points, were digitized to obtain variables such as velocity ( , amplitude of heave , and the frequency of oscillations during the gallop cycle. These variables represent the principal parameters of a biomechanical model that computes the power output of individuals. Power output and mechanical Cost of transport were calculated and compared between the four pinniped species following the animals’ center of mass. The quadrupedal gait of otariids proved to have significantly lower costs of transport, power outputs, and vertical displacements compared to the terrestrial gait of the phocids. Therefore, California sea lions locomote more efficiently on land when compared to phocids; the gait of otariids being more similar to that of terrestrial mammals.