Researcher(s)
- Ava Barrera, Biological Sciences, University of Delaware
Faculty Mentor(s)
- Jennifer Wyffels, Bioinformatics, University of Delaware
Abstract
Many shark species exhibit shifts in tooth morphology that correspond with changes in diet throughout ontogeny. Sand tiger sharks are aplacental viviparous sharks that reproduce through adelphophagy, a process in which developing embryos use precociously formed teeth to escape their egg capsules and eliminate sibling embryos within the uterus. Following this stage, embryos continue to feed on unfertilized eggs supplied by the mother until birth. After a gestation period of approximately ten months, pups are born at nearly one meter in length and must immediately begin foraging independently. Despite the unique reproductive biology of the sand tiger shark (Carcharias taurus), ontological changes in tooth morphology have not been thoroughly investigated.
To examine how tooth morphology changes throughout development and may relate to shifting feeding strategies, teeth from neonatal, juvenile, and adult sand tiger sharks were imaged using micro-computed tomography (micro-CT) and reconstructed in three dimensions using NRecon, DataViewer, and Amira software. A suite of morphological measurements was collected from each reconstructed tooth and compared among life stages.
Distinct differences in tooth morphology were observed. Neonatal teeth lacked lateral cusplets, which first appeared in juvenile specimens and were retained in adults. Additional morphological variation among life stages suggests developmental changes in tooth form that may reflect transitions in feeding ecology as individuals mature. These findings provide new insight into the relationship between tooth development, feeding function, and the reproductive strategy of the sand tiger shark.