Senckenbergiana lethaea

, Volume 82, Issue 1, pp 315–324 | Cite as

The evolution of the placozoa: A new morphological model

  • Tareq Syed
  • Bernd Schierwater
Constructional Morphology and Evolution


The evolutionary history of the placozoanTrichoplax adhaerens is reconstructed from a hypothetical ‘gallertoid’ ancestor. According to this approach the Placozoa derived from an early benthic gallertoid stage, the ‘placuloid’. The sequence of morphological transformations leading to the placozoan bauplan can be deduced from biomechanical and functional constraints. From the viewpoint of constructional morphology the only known placozoan speciesTrichoplax adhaerens represents a member of a basal metazoan stem line which evolved distinctly from other phyla and earlier than sponges and coelenterates. Since theTrichoplax bauplan is still similar to the hypothetical placuloid and gallertoid stages, the given reconstruction provides some specifications for the gallertoid model.

Key words

Placozoa Trichoplax gallertoid hypothesis placuloid diploblast phylogeny 


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  1. Adoutte, A., Balavoine, G., Lartillot, N., et al. (2000): The new animal phylogeny. Reliability and implications. Proc. Nat. Am. Sc.97/9: 4453–4456.CrossRefGoogle Scholar
  2. Aleshin, V. V., Vladychenskaya, N. S., Kedrova, O. S., et al. (1995): Phylogeny of invertebrates deduced from 18S rRNA comparisons. Molecular Biology29/6: 843–855.Google Scholar
  3. Ax, P. (1995): Das System der Metazoa I. 226pp. Gustav Fischer Verlag Jena, New York.Google Scholar
  4. Behrendt, G. &Ruthmann, A. (1986): The cytoskeleton of the fiber cells ofTrichoplax adhaerens (Placozoa). Zoomorphology106: 123–130.CrossRefGoogle Scholar
  5. Birstein, V. J. (1989): On the Karyotype ofTrichoplax sp. (Placozoa). Biol. Zent. Bl.108: 63–67.Google Scholar
  6. Bonik, K., Grasshoff, M. &Gutmann, W. F. (1976): Die Evolution der Tierkonstruktionen I. Natur und Museum106: 129–143.Google Scholar
  7. Boute, N., Exposito, J. Y., Boury-Esnault, N., et al. (1996): Type IV collagen in sponges, the missing link in basement membrane ubiquity. Biol Cell88 (1–2): 37–44.CrossRefGoogle Scholar
  8. Bridge, D. M. (1994): Phylogeny and life cycle evolution in the phylum cnidaria. PHD-Thesis, Yale University.Google Scholar
  9. Brusca, R. C. &Brusca, G. J. (1990): Invertebrates. 922 pp. Sinauer associates, Massachuchetts.Google Scholar
  10. Buchholz, K. &Ruthmann, A. (1995): The Mesenchyme-Like Layer of the Fiber Cells ofTrichoplax adhaerens (Placozoa), a Syncytium. Z. Naturforsch.50c: 282–285.Google Scholar
  11. Bütschli, O. (1884): Bemerkungen zur Gastraeatheorie. Morph. Jahrb.9: 415–427.Google Scholar
  12. Cloud, P. &Glaessner, M. F. (1982): The Ediacaran period and system: Metazoa inherit the earth. Science217: 783–792.CrossRefGoogle Scholar
  13. Collins, A. G. (1998): Evaluating multiple alternative hypotheses for the origin of Bilateria: An analysis of 18S rRNA molecular evidence. Proc Natl Acad Sci USA vol95: 15458–15463.CrossRefGoogle Scholar
  14. Grassé, P. P. (1961): Traité de Zoologie IV: Plathelminthes, Mésozoaires, Acanthocéphales, Mémertiens. 944 pp. Masson, Paris.Google Scholar
  15. Grasshoff, M. (1987): Cnidarian phylogeny — a biomechanical approach. Palaeontographica Amer.117: 127–135.Google Scholar
  16. Grasshoff, M. (1992a): Die Evolution der Schwämme I. Natur und Museum122(7): 201–210.Google Scholar
  17. Grasshoff, M. (1992b): Die Evolution der Schwämme II. Natur und Museum122(8): 237–247.Google Scholar
  18. Grasshoff, M. (1993): Die Evolution der Tiere in neuer Darstellung. Natur und Museum123(7): 204–215.Google Scholar
  19. Grasshoff, M. (1995): Die Evolution der Tiere. Loseblattmappe Nr. 6, Naturmuseum Senckenberg.Google Scholar
  20. Grasshoff, M. &Gudo, M. (1998a): Die Evolution der Coelenteraten I. Natur und Museum128: 129–138.Google Scholar
  21. Grasshoff, M. &Gudo, M. (1998b): Die Evolution der Coelenteraten II. Natur und Museum128: 329–341.Google Scholar
  22. Grell, K. G. (1971a): Über den Ursprung der Metazoen. Mikrokosmos60: 97–102.Google Scholar
  23. Grell, K. G. (1971b):Trichoplax adhaerens F. E. Schulze und die Entstehung der Metazoen. Naturw. Rundsch.24/4: 160–161.Google Scholar
  24. Grell, K. G. (1971c): Embryonalentwicklung beiTrichoplax adhaerens F. E. Schulze. Naturwiss:58: 507.CrossRefGoogle Scholar
  25. Grell, K. G. (1972): Eibildung und Furchung vonTrichoplax adhaerens F. E. Schulze (Placozoa). Z. Morph. Tiere73: 297–314.CrossRefGoogle Scholar
  26. Grell, K. G. &Benwitz, G. (1971): Die Ultrastruktur vonTrichoplax adhaerens F. E. Schulze. Cytobiologie4: 216–240.Google Scholar
  27. Grell K.G. (1974): Vom Einzeller zum Vielzeller. Hundert Jahre Gastraea-Theorie. Biol. i. u. Zeit4: 65–71CrossRefGoogle Scholar
  28. Grell, K. G. &Benwitz, G. (1981): Ergänzende Untersuchungen zur Ultrastruktur vonTrichoplax adhaerens F. E. Schulze (Placozoa). Zoomorphology98: 47–67.CrossRefGoogle Scholar
  29. Grell, K. G. &Ruthmann, A. (1991): Placozoa. In: Microscopic anatomy of invertebrates, vol. 2 (ed. FW Harrison & JA Westfall): 13–27. Wiley-Liss New York.Google Scholar
  30. Gruner, H. E. (1993): Einführung. In:Kaestner, A. (ed.): Lehrbuch der Speizellen Zoologie Band I/1: Protozoa, Placozoa, Porifera.Google Scholar
  31. Gutmann, W. F. (1989): Die Evolution hydraulischer Konstruktionen. 201 pp. Verlag Waldemar Kramer, Frankfurt a. M.Google Scholar
  32. Haeckel, E. (1874): Die Gastraea-Theorie, die phylogenetische Classification des Thierreiches und die Homologie der Keimblätter. Jenaische Z. f. Naturwiss.8: 1–55.Google Scholar
  33. Hyman, L. H. (1940): The invertebrates: Protozoa through Ctenophora. 726 pp. McGraw Hill, New York.Google Scholar
  34. Krumbach, T. (1907):Trichoplax, die umgewandelte Planula einer Hydromeduse. Zool. Anz.31: 450–454.Google Scholar
  35. Kuhl, W. &Kuhl, G. (1966): Untersuchungen über das Bewegungsverhalten vonTrichoplax adhaerens F. E. Schulze. Z. Morph. Ökol. Tiere56: 417–435.CrossRefGoogle Scholar
  36. Lafay, B., Boury-Esnault N., Vacelet J. et al. (1992): An analysis of partial 28S ribosomal RNA sequences suggests early radiations of sponges. BioSystems28: 139–151.CrossRefGoogle Scholar
  37. Lankester, E. Ray (1877): Notes on the embryology and classification of the animal kingdom. Quart. Journ. micr. Sci.17: 399–454.Google Scholar
  38. Metschnikoff, E. (1882): Vergleichende embryologische Studien. Z. f. wiss. Zool.36: 433–444.Google Scholar
  39. Odorico, D. M. &Miller, D. J. (1997): Internal and external relationships of the Cnidaria: implications of primary and predicted secondary structure of the 5′-end of the 23S-like rDNA. Proc. R. Soc. Lond. B264: 77–82.CrossRefGoogle Scholar
  40. Raff, R. A. (1996): The Shape of Life. 520 pp. University of Chicago Press.Google Scholar
  41. Rai, V. &Gautam, R. (1999): Evaluating evidence of ancient animals. Science284: 1235–1235.CrossRefGoogle Scholar
  42. Ruthmann, A. (1977): Cell differentiation, DNA content and chromosomes ofTrichoplax adhaerens F. E. Schulze. Cytobiologie15: 58–64.Google Scholar
  43. Ruthmann, A. (1997): Placozoa. In: Westheide W. & Rieger R.: Spezielle Zoologie Teill: Einzeller und Wirbellose Tiere. 909 pp. Gustav Fischer Verlag Stuttgart, Jena, New York.Google Scholar
  44. Ruthmann, A. (2000): Evolution und die Vielfalt des Lebens. 466 pp. Shaker Verlag Aachen.Google Scholar
  45. Ruthmann, A., Behrendt, G. &Wahl, R. (1986): The ventral epithelium ofTrichoplax adhaerens (Placozoa): Cytoskeletal structures, cell contacts and endocytosis. Zoomorphology106: 115–122.CrossRefGoogle Scholar
  46. Ruthmann A., Grell K.G. &Benwitz G. (1981): DNA-Content and fragmentation of the egg nucleus ofTrichoplax adhaerens. Z. Naturforsch.60: 564–567.Google Scholar
  47. Ruthmann, A. &Wenderoth, H. (1975): Der DNA-Gehalt des primitiven MetazoonsTrichoplax adhaerens F. E. Schulze. Cytobiologie10: 421–431.Google Scholar
  48. Salvini-Plawen, L. V. (1978): On the origin and evolution of the lower Metazoa. Z. zool. Syst. Evolut.-forsch.16: 40–88.Google Scholar
  49. Schierwater, B. &Kuhn, K. (1998): Homology of Hox genes and the zootype concept in early metazoan evolution. Mol. Phyl. Evol.9/3: 375–381.CrossRefGoogle Scholar
  50. Schierwater, B. &de Salle, R. (2001): Current problems with the zootype and the early evolution of Hox genes. Mol. Dev. Evol.201: 169–174.CrossRefGoogle Scholar
  51. Schubotz, H. (1912): IstTrichoplax die umgewandelte Planula einer Hydromeduse? Zool. Anz.39: 582–585.Google Scholar
  52. Schuchert, P. (1993):Trichoplax adhaerens (Phylum Placozoa) has Cells that react with antibodies against the neuropeptide RF amide. Acta Zoologica (Stockholm), Vol.74 (2): 115–117.CrossRefGoogle Scholar
  53. Schulze, F. E. (1883):Trichoplax adhaerens nov. gen. nov. spec. Zool. Anz.6: 92–97.Google Scholar
  54. Schulze, F. E. (1891): ÜberTrichoplax adhaerens. Physik. Abh. Kgl. Akad. Wiss. Berlin: 1–23.Google Scholar
  55. Schwartz, V. (1984): Das radialpolare Differenzierungsmuster beiTrichoplax adhaerens F. E. Schulze (Placozoa). Z. Naturforsch.39c: 818–832.Google Scholar
  56. Seidel, F. (1978): Morphogenese der Tiere. Lieferung 1: A I. Einleitung. Cnidaria. 415 pp.; Jena (VEB Gustav Fischer).Google Scholar
  57. Seilacher, A., Bose, P. K. &Pflüger, F. (1998): Triploblastic animals more than one billion years ago: trace fossil evidence from India. Science282: 80–83.CrossRefGoogle Scholar
  58. Storch, V. &Welsch, U. (1989): Evolution. 295pp. dtv MünchenGoogle Scholar
  59. Storch, V. &Welsch, U. (1997): Systematische Zoologie. 804 pp. Gustav Fischer Verlag Stuttgart Jena Lübeck Ulm.Google Scholar
  60. Thiemann, M. (1990): Alternativen der Morphogenese und der ungeschlechtlichen Vermehrung des primitiven VielzellersTrichoplax adhaerens F. E. Schulze 1883 (Placozoa). Dissertation Ruhr-Universität Bochum.Google Scholar
  61. Thiemann, M. &Ruthmann, A. (1989): Microfilaments and microtubules in isolated fibre cells ofTrichoplax adhaerens (Placozoa). Zoomorphology109: 89–96.CrossRefGoogle Scholar
  62. Thiemann, M. &Ruthmann, A. (1990): Spherical forms ofTrichoplax adhaerens. Zoomorphology110: 37–45.CrossRefGoogle Scholar
  63. Vermeij, G. J. (1996): Animal origins. Science274: 525–526.CrossRefGoogle Scholar
  64. Wenderoth, H. (1986): Transepithelial cytophagy byTrichoplax adhaerens F. E. Schulze (Placozoa) feeding on yeast. Z. Naturforsch.41c: 343–347.Google Scholar

Copyright information

© E. Schweizerbart’sche Verlagsbuchhandlung 2002

Authors and Affiliations

  • Tareq Syed
    • 1
  • Bernd Schierwater
    • 1
  1. 1.Institute of Animal Ecology and Cell Biology, Division of Ecology and EvolutionTiHo HannoverHannover

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