Dentition and tooth replacement rate of the narrownose smooth hound shark Mustelus schmitti

BELLEGGIA MAURO; FIGUEROA DANIEL E.; MASSA ANA; BREMEC CLAUDIA

Albuquerque, Nuevo Mexico

Congreso; Joint Meeting of Ichthyologists and Herpetologists; 2013

American Society of Ichthyologist and Herpertologists (ASIH)

The genus Mustelus is the most specious genus of the Family Triakidae comprising at least 31 species. The narrownose smoothhound shark Mustelus schmitti inhabits coastal waters from southern Brazil (27º S) to Patagonia Argentina (47º45´S). A total of 47 males and 56 females of M. schmitti were collected on scientific trawl surveys conducted by the The National Institute of Fisheries Research and Development (INIDEP) in Argentina during November 2007, November and December 2008. To carry out quantitative and qualitative analyses, dental laminas were extracted from the jaw cartilage and attached to onionskin paper for the dehydration treatment, maintaining their original jaw position. Tooth replacement rate was estimated following established methods used for fossil sharks based on the premise that tooth length within each row decreases from the lingual to the labial side of the jaw as a consequence of wear. Thus, the length difference between consecutive teeth in four representative rows should be proportional to the tooth replacement rate. Mustelus schmitti exhibits homodentition, where teeth are similar is shape or design, arranged in a semi-pavement like dentition. The dental formula was 47-63 / 50-63 for juveniles, and 50-77 / 50-69 for adult specimens. Teeth from the symphysial and adsymphysial rows showed higher wear and faster replacement rates than adcommissural and commissural rows. The estimated mean replacement rate was four days/series. Considering the dental formulae and replacement rate, M. schmitti replaces approximately 5350 teeth each year throughout their life time.