How otariids walk: a comparative axial analysis of the hind limb movements of California and South American sea lions

Abstract

AbstractSeals exist at the intersection of land and water. This is especially true of eared seals (otariids), which are both highly adapted to forelimb swimming and retain the ability to walk on land. The precise nature and evolutionary history of their walking ability remains obscure, however. Here, we use axial analysis to compare the hind limb movements of California and South American sea lions with those of terrestrial plantigrades mammals. We show that, despite notable differences in foot orientation and joint position, all of our study species employ similar movements around the same centers of rotation. Our results suggest that otariid hind limbs and, in particular, the hallux play a substantial role in supporting and propelling the body during walking.