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

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Abstract

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.

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Acknowledgments

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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Authors and Affiliations

  1. Department of Biology, University of Modena and Reggio Emilia, Via Campi 213/D, 41125, Modena, Italy

    Roberto Guidetti, Trevor Marchioro, Luca Sarzi Amadè, Roberto Bertolani & Lorena Rebecchi

  2. Department of Education and Human Sciences, University of Modena and Reggio Emilia, Via Allegri 9, 42121, Reggio Emilia, Italy

    Tiziana Altiero

  3. The Russian Presidential Academy of National Economy and Public Administration, Vladimir Branch, Gorkogo St. 59A, 600017, Vladimir, Russia

    Alexandra M. Avdonina

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  1. Roberto Guidetti
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  2. Tiziana Altiero
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  3. Trevor Marchioro
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  4. Luca Sarzi Amadè
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  5. Alexandra M. Avdonina
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  6. Roberto Bertolani
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Correspondence to Roberto Bertolani.

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Communicated by A. Schmidt-Rhaesa.

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Guidetti, R., Altiero, T., Marchioro, T. et al. Form and function of the feeding apparatus in Eutardigrada (Tardigrada). Zoomorphology 131, 127–148 (2012). https://doi.org/10.1007/s00435-012-0149-0

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  • DOI: https://doi.org/10.1007/s00435-012-0149-0

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