Meeting Abstract
Trabecular bone forms a porous architecture that changes in vivo to support mechanical demands on the body and can reflect the degree of an animal’s species-specific precociality; skeletons must be stronger and stiffer in animals that are mobile soon after birth. Previous studies have shown that secondarily adapted aquatic mammals have vertebral microarchitecture and loading regimes that differ from their terrestrial counterparts. The goals of this study were to investigate the following in a precocial obligate swimmer: (1) variation of mechanical properties among regions of the vertebral column and ontogenetic development and (2) relationships between vertebral process lengths and mechanical properties of bone tested in the orientation parallel to each process. We investigated bone behavior in the Florida manatee (Trichechus manatus latirostris) at various regions along the vertebral column. Vertebrae were dissected and machined into three orientations for compressive tests and stiffness, yield strength, and toughness were calculated from stress-strain curves. We found significant variation among column regions and age groups. Perinatal bone properties were statistically consistent among column regions. Adult bone was the most resilient and strong in posterior regions but stiffest in anterior regions. Calf bone properties were similar to perinatals in the anterior regions, but matched the older age groups in posterior regions, suggesting that caudal vertebral bone ossifies first in manatee development to support undulatory locomotion. Transverse process lengths had moderate positive correlations with mediolaterally tested bone for all properties, potentially providing greater bone surface area for muscle attachment and increasing force production on vertebrae.
