Impact of Allometry and Feeding Biomechanics on Ontogenetic Dietary Shifts in Three Coastal Sharks


Meeting Abstract

20-3  Monday, Jan. 4 10:45  Impact of Allometry and Feeding Biomechanics on Ontogenetic Dietary Shifts in Three Coastal Sharks CULLEN, J.A.*; PLUMLEE, J.D.; TINHAN, T.; WELLS, R.J.D.; MARSHALL, C.D.; Texas A&M University, College Station; Texas A&M University, Galveston; Texas A&M University, Galveston; Texas A&M University, Galveston; Texas A&M University, College Station; Texas A&M University, Galveston; Texas A&M University, College Station jcullen@tamu.edu

Allometric growth and feeding biomechanics are important factors for studying changes in bite force production and how this influences prey selection over ontogeny. Sharks are an interesting model system to test these parameters since they often undergo one or more ontogenetic dietary shifts towards functionally challenging prey. These dietary shifts are likely influenced by increasing bite force production and gape. In some shark species, bite force has been observed to increase significantly from parturition through juvenile stages due to positive allometry of the jaw adducting mechanism. However, our knowledge regarding these patterns is restricted to a limited number of species and size classes. Bull (Carcharhinus leucas), blacktip (Carcharhinus limbatus), and bonnethead (Sphyrna tiburo) sharks are common along the Texas coast, and coastal habitats in Texas function as nurseries for these species. Mechanical advantage, muscle mass, and anatomical cross-sectional area were compared to determine which contributed most to the scaling of bite force. Stomach contents of size classes for all three species were compared to determine if and when dietary shifts occur with respect to changes in bite force. Comparisons among all three species will begin to characterize their relative feeding performance from morphological, biomechanical, and ecological perspectives.

the Society for
Integrative &
Comparative
Biology