Meeting Abstract
The aquatic specializations of phocid seals has restricted their ability to locomote on land by primarily using spinal flexion. This terrestrial gait has limited the performance (i.e., speed, endurance) of phocids. The northern elephant seal, Mirounga angustirostris, is the second largest phocid seal with males and females reaching 2,000 kg and 600 kg, respectively. While elephant seals are proficient swimmers, diving deeper and longer than any other pinniped, their extreme size can be especially restrictive to terrestrial movement when using spinal flexion. The kinematics of terrestrial locomotion in northern elephant seals was analyzed from video recordings of animals observed on the beach of Año Nuevo State Reserve, CA. Terrestrial motions were quantified using ProAnalyst software. The seals exhibited dorsoventral spinal flexions, where the chest, pelvic region, and fore flippers served as the main points of contact with the ground. The spine was flexed by a wave that traveled anteriorly along the body. The spinal wave and fore flippers were used to lift the chest off the ground, and subsequently the fore flippers were retracted to pull the body forward. Simultaneously, the pelvic region served as a friction point from which the body extended forward. Frequency of locomotor spinal flexions (1.6±0.3 Hz) was found to be at its highest when velocity was between 0.3–0.5 BL/s. Contact with the ground differed between the fore flippers and pelvic region as the duty cycle ranged from 0.59–0.97 and 0.08–0.48, respectively. Despite their massive size, these animals can reach speeds up to 4.8 m/s (0.7 BL/s).
