TitleFunctional implications of ontogenetically and sexually dimorphic dentition in the eastern shovelnose ray, Aptychotrema rostrata
Publication TypeJournal Article
Year of Publication2014
AuthorsGutteridge AN, Bennett MB
Date PublishedJan
Type of ArticleArticle
ISBN Number0022-0949
Accession NumberZOOREC:ZOOR15005025083
KeywordsAnimalia, Chordata, Vertebrata, Pisces, Chondrichthyes, Elasmobranchii,, Aptychotrema rostrata (Rhinobatidae)., Aptychotrema rostrata [Biomechanics / / ] [Dentition / / ] [Jaws / Jaw, Biophysics, Chordates, Fish, Life cycle and development, morphology / ] [Sex differences / Sexual dimorphism / ] [Development /, Ontogeny / ]., Rajiformes, Rhinobatidae, Reproduction, Skeletal and supporting structures, Skeleton, Skull, Vertebrates
AbstractUnlike other elasmobranchs, batoids exhibit sexually dimorphic dentition. The functional implications of such dentition, however, remain understudied. For the present study, ontogenetic and sexual dimorphism in tooth and jaw structure, together with the functional implications of this dimorphism, were determined in the eastern shovelnose ray, Aptychotrema rostrata. Sexually dimorphic dentition and jaw structure was first observed in sub-adult age classes, with males developing a pronounced lower jaw at the symphysis. Monognathic heterodonty was prominent in mature males, with teeth in the symphyseal region developing significantly greater heights and sharpness ratios in comparison to females. Ex vivo mechanical grip strength tests were used to determine simulated bite-grip tenacity. The mean peak pull-out forces required to withdraw a section of a dissected pectoral fin from between jaws closed with a constant occlusal force was highest for mature males, intermediate for mature females and lowest for immature females and males. Although the species exhibits ontogenetic variations in diet, these were unrelated to sex. Rather, the larger and highly cuspidate teeth of mature males increased the bite-grip tenacity, which likely aids in copulation.