Journal of Biosciences

, Volume 36, Issue 1, pp 117–121 | Cite as

Efficiency of wear and decalcification technique for estimating the age of estuarine dolphin Sotalia guianensis

  • Nicolle V SydneyEmail author
  • Emygdio LA Monteiro-Filho


Most techniques used for estimating the age of Sotalia guianensis (van Bénéden, 1864) (Cetacea; Delphinidae) are very expensive, and require sophisticated equipment for preparing histological sections of teeth. The objective of this study was to test a more affordable and much simpler method, involving of the manual wear of teeth followed by decalcification and observation under a stereomicroscope. This technique has been employed successfully with larger species of Odontoceti. Twenty-six specimens were selected, and one tooth of each specimen was worn and demineralized for growth layers reading. Growth layers were evidenced in all specimens; however, in 4 of the 26 teeth, not all the layers could be clearly observed. In these teeth, there was a significant decrease of growth layer group thickness, thus hindering the layers count. The juxtaposition of layers hindered the reading of larger numbers of layers by the wear and decalcification technique. Analysis of more than 17 layers in a single tooth proved inconclusive. The method applied here proved to be efficient in estimating the age of Sotalia guianensis individuals younger than 18 years. This method could simplify the study of the age structure of the overall population, and allows the use of the more expensive methodologies to be confined to more specific studies of older specimens. It also enables the classification of the calf, young and adult classes, which is important for general population studies.


Age estimation GLG Sotalia guianensis 



We thank Regina C Zanelatto (Nina) for the donation of the teeth collection used in this study; Fernando A Sedor for his support during the development of this study; Museu de Ciências Naturais and Departamento de Zoologia, Universidade Federal do Paraná, for the use of their facilities; Rodrigo Gonçalves, Eduardo Almeida, José Carlos Motta, Roberto Shimizu, Eleonora Trajano, André Barreto, Rogério Langue and the anonymous referees for their constructive criticism and suggestions on the study and this manuscript.


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Copyright information

© Indian Academy of Sciences 2011

Authors and Affiliations

  • Nicolle V Sydney
    • 1
    Email author
  • Emygdio LA Monteiro-Filho
    • 2
    • 3
  1. 1.Instituto de BiociênciasUniversidade de São PauloSão PauloBrasil
  2. 2.Departamento de ZoologiaSetor de Ciências BiológicasCuritibaBrasil
  3. 3.Instituto de Pesquisa em CananéiaCananéiaBrasil

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