, Volume 131, Issue 2, pp 127–148 | Cite as

Form and function of the feeding apparatus in Eutardigrada (Tardigrada)

  • Roberto Guidetti
  • Tiziana Altiero
  • Trevor Marchioro
  • Luca Sarzi Amadè
  • Alexandra M. Avdonina
  • Roberto BertolaniEmail author
  • Lorena Rebecchi
Original Paper


Tardigrade feeding apparatus is a complex structure with considerable taxonomic significance that can be schematically divided into four parts: buccal ring, buccal tube, stylet system, and pharynx. We analyzed the fine morphology and the tridimensional organization of the tardigrade buccal–pharyngeal apparatus in order to clarify the relationships between form and function and to identify new characters for systematic and phylogenetic studies. We conducted a comparative analysis of the cuticular structures of the buccal–pharyngeal apparatuses of twelve eutardigrade species, integrating data obtained by SEM and LM observations. Morphological diversity was observed and new cuticular structures such as the stylet coat of the stylet system were identified. The synthesis of the buccal–pharyngeal apparatus during molting was also analyzed obtaining a clear developmental sequence of its resynthesis. These findings lead us to redefine the previous interpretations of the functioning mechanisms of the buccal–pharyngeal apparatus and provide a more specific relationship between tardigrade diet and the anatomy of their feeding apparatuses. In addition, the detection by energy-dispersive X-ray spectroscopy of calcium in the stylets, buccal tube, and placoids of eutardigrade species (i.e., Milnesium tardigradum, Paramacrobiotus richtersi) indicates that CaCO3 incrustations are not an exclusive feature of heterotardigrades and lead to suppose that this trait was present in the ancestors of both classes.


Buccal–pharyngeal apparatus Calcium carbonate Evolution Foregut Molting X-ray spectroscopy 



The authors wish to thank Paul Bartels (Warren Wilson College, Asheville, North Carolina, U.S.A.) for the great courtesy of revising the English. The research is part of the project MoDNA granted by Fondazione Cassa di Risparmio di Modena (Italy) and the University of Modena and Reggio Emilia (Italy).


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Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  • Roberto Guidetti
    • 1
  • Tiziana Altiero
    • 2
  • Trevor Marchioro
    • 1
  • Luca Sarzi Amadè
    • 1
  • Alexandra M. Avdonina
    • 3
  • Roberto Bertolani
    • 1
    Email author
  • Lorena Rebecchi
    • 1
  1. 1.Department of BiologyUniversity of Modena and Reggio EmiliaModenaItaly
  2. 2.Department of Education and Human SciencesUniversity of Modena and Reggio EmiliaReggio EmiliaItaly
  3. 3.The Russian Presidential Academy of National Economy and Public AdministrationVladimir BranchVladimirRussia

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