Meeting Abstract
Dusky smoothhound sharks inhabit shallow inshore waters where they forage for crustaceans, with crabs comprising the largest dietary item by percentage and volume. They mature relatively rapidly, within 2-4 years of age, and having molariform teeth are well adapted for feeding on durophagous prey. Whether a dietary change occurs over this relatively short period is unknown. Shape change over ontogeny was analyzed using geometric morphometric analyses of the mandibular and hyoid arch cartilages in twenty-four individuals spanning most of the size range (32-116 cm TL). Mechanical stiffness, Poisson’s ratio, and percent mineralization were quantified in the same individuals. Geometric morphometric analyses show that while some shape changes occurred, the jaw and hyoid elements remain largely isometric over ontogeny. In most elements, cross-sectional area and percent mineralization increases with size as expected, leading to consistent strain, and thus stress over ontogeny. Poisson’s Ratio decreases with % mineralization over ontogeny in the mandibular elements, but not the hyoid arch elements. Young’s Modulus increases in some elements over ontogeny with increasing mineralization, but remains consistent in others. An inflection point exists in the stress-strain curve that may indicate mechanical property changes of tesserae-ligament interactions during compression.
