Trumble, Stephen John.Moore, Colby D.2014-09-052014-09-052014-082014-09-05Moore, C. D., Crocker, D. E., Fahlman, A., Moore, M. J., Willoughby, D. S., Robbins, K. A., Kanatous, S. B., Trumble, S. J. "Ontogenetic changes in skeletal muscle fiber type, fiber diameter and myoglobin concentration in the Northern elephant seal (Mirounga angustirostris)." Frontiers in Physiology 5 (2014): 217.http://hdl.handle.net/2104/9178The muscular biochemistry and respiratory morphology of diving mammals are closely intertwined through the utilization and allocation of inspired oxygen for metabolism. Marine mammal physiological mechanisms and adaptations are of great intrigue due to the heightened environmental pressures that these animals are routinely subjected. These species also experience varying degrees of ischemia, hypoxemia and gas tissue saturation, which are pathological in terrestrial mammals. Data included in this dissertation suggest a unique skeletal muscle fiber type profile for the deep-diving Northern elephant seal; a profile predominately comprised of enlarged aerobic type I myofibers. In addition, enzymatic data suggest that diving mammals maintain higher levels of aerobic enzymes in primary locomotory muscle and that muscle-based enzymes degrade rapidly and variably with temperature and time. Histological analysis of harbor seal tracheal rings microscopically describes a unique continuity of cartilage that correlates with lung compression, depth at which lungs collapse, as well as maximum dive depth. Cumulatively, biochemical and structural adaptations allow diving mammals to reach extensive depth, while maintaining homeostatic levels of on-board gasses and avoiding dive-related injury. Ultimately, this research highlights the relationship between morphology, physiology and life history of these animals.en-USBaylor University theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. Contact librarywebmaster@baylor.edu for inquiries about permission.Marine mammals.Diving physiology.ThesisWorldwide access.Access changed 1/27/17.