Cheston Peterson

Honors in Marine Biology

Major: Marine Biology

Supervisor: Thomas Lankford, Biology and Marine Biology

Implications of Seasonally Sexually Dimorphic Dentition in Regard to Feeding Ability and Effects of Tooth Damage in the Bluntnose Stingray, Dasyatis say

Sexually dimorphic dentition has evolved in several species of Dasyatid stingrays wherein males replace their molariform teeth with cuspidate teeth during the mating season. Previous research has revealed that cuspidate dentition may increase male reproductive success through enhanced grip strength and improved ability to grasp and hold females during copulation. The replacement of cuspidate teeth with molariform teeth following each mating season is intriguing as it suggests that cuspidate teeth may be inferior as feeding structures and may compromise a male’s ability to crush hard-shelled prey during non-mating periods. We explored trade-offs in the evolution of dental sexual dimorphism in the bluntnose stingray (Dasyatis say) by testing for potential feeding-related costs of cuspidate dentition, including 1) investigating whether the diets of wild individuals vary with dentition type 2) comparing bite forces required by mating and non-mating teeth to crush shelled prey, 3) examining the susceptibility of mating teeth to damage during feeding, and 4) testing whether tooth damage compromises male grip strength. We did not find a significant difference in the presence of hard-shelled prey in the stomach contents of rays with molariform and cuspidate dentitions. Forces required to break shelled prey were not significantly different between female, immature male, and mature male rays; however, cuspidate teeth were significantly more prone to damage. Our analysis found no significant difference between grip strengths of jaws with molariform and cuspidate teeth, and found that serious tooth damage did not affect grip in jaws exhibiting cuspidate dentition.