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Morphology and Functional Anatomy

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Water Bears: The Biology of Tardigrades

Part of the book series: Zoological Monographs ((ZM,volume 2))

Abstract

Tardigrades are microscopic aquatic bilaterians that despite their size have a complex morphology and anatomy. These minute animals need a surrounding film of water to be active, and tardigrades residing in terrestrial environments live in moist microhabitats. The latter species are referred to as semiterrestrial, and they endure rapid dehydration by losing water over highly permeable integuments while forming a quiescent tun. Species of the class Eutardigrada are predominantly semiterrestrial and limnic with a relatively uniform morphology and anatomy. Heterotardigrades (class Heterotardigrada) comprising echiniscoideans and arthrotardigrades are much more diverse with highly variable external morphologies, ranging from clearly segmented species, over species with extremely large external sense organs and cuticular wings to species with a more “bear”-like eutardigrade body outline. In this chapter, we review the current understanding of tardigrade morphology and functional anatomy and put focus on tardigrade diversity emphasizing the often neglected marine arthrotardigrades. We give an introduction to the structure and function of major tardigrade organ systems, including the integument, body cavity, and digestive, muscular, nervous, and reproductive systems, and we highlight the diversity of tardigrade sensory appendages and overall external morphology.

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Acknowledgments

Funding came from the Carlsberg Foundation and the Danish Council for Independent Research (grant no. DFF – 4090-00145).

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Authors and Affiliations

  1. Department of Biology, University of Copenhagen, Copenhagen, Denmark

    Nadja Møbjerg, Aslak Jørgensen & Ricardo C. Neves

  2. Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark

    Reinhardt Møbjerg Kristensen

Authors
  1. Nadja Møbjerg
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  2. Aslak Jørgensen
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  3. Reinhardt Møbjerg Kristensen
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  4. Ricardo C. Neves
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Correspondence to Nadja Møbjerg .

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Editors and Affiliations

  1. Institute of Biological Materials and Biomolecular Systems, University of Stuttgart, Stuttgart, Germany

    Ralph O. Schill

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Møbjerg, N., Jørgensen, A., Kristensen, R.M., Neves, R.C. (2018). Morphology and Functional Anatomy. In: Schill, R. (eds) Water Bears: The Biology of Tardigrades. Zoological Monographs, vol 2. Springer, Cham. https://doi.org/10.1007/978-3-319-95702-9_2

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