Denticle morphology in the Pacific Spiny Dogfish, Squalus suckleyi

Abstract

To learn more about the denticle morphology and potential for replacement in the denticles of Squalus suckleyi, the Pacific spiny dogfish, a survey of denticle shapes using scanning electron microscopy (SEM) was conducted. This provides the knowledge of what is expected in denticle shape and serves as a baseline for future comparisons. Denticle shapes were seen to change over the regions of the body as well as over ontogeny. Denticle shapes were also linked to the function at the different regions of the body. Since there is no dental lamina in denticles, denticles were not seen to replace like oral teeth which went against the predicted expectations. The emergence pattern of the denticles in embryos also went against the predictions as it was different from the previously recorded two dorsolateral rows. These two unexpected findings raise questions and provide a basis for future research. In addition, histology and micro-CT scan data provided information on how the denticles emerge in the embryos and provide a comparison of how similar replacement in adults and this first emergence in embryos look.