Ontogenetic changes in the tooth morphology of bull sharks (Carcharhinus leucas)

Teeth are an integral component of feeding ecology with a clear link between tooth morphology and diet, as without suitable dentition prey cannot be captured nor broken down for consumption. Bull sharks Carcharhinus leucas undergo an ontogenetic niche shift, which raises the question: does tooth morphology change with ontogeny? Teeth were measured using traditional morphometrics and an Elliptic Fourier Analysis to determine if morphology varied with position in the jaw and if there was an ontogenetic morphological change concordant with this niche shift. Tooth shape, surface area and thickness were measured. Significant ontogenetic differences in tooth morphology as a function of position in the jaw and shark total length were found, with upper and lower jaws of bull sharks presenting two different tooth morphologies. Tooth shape and thickness fell into two groupings, anterior and posterior in both the upper and lower jaws. Tooth surface area, however, indicated three groupings, mesial, intermediate and distal, in both the upper and lower jaws. While tooth morphology changed significantly with size with an inflexion at sharks of 135 cm total length, each morphological aspect retained the same tooth groupings throughout. These ontogenetic differences in tooth morphologies reflect tooth strength, prey handling and heterodonty.