Demosponges
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Demospongiae
Barrel sponge (Xestospongia testudinaria)
Scientific classification
Kingdom: Animalia Phylum: Porifera Class: Demospongiae Sollas, 1885
Subclasses
Homoscleromorpha Tetractinomorpha Ceractinomorpha See text for orders.

Red volcano sponge (Acarnus erithacus).

The Demospongiae are the largest class in the phylum Porifera. Their "skeletons" are made of spicules consisting of fibers of the protein spongin, the mineral silica, or both. They contain 90% of all species of sponges and are predominantly leuconid structural grade.

There are many diverse orders in this class, including all of the large sponges. Most are marine dwellers, but several live in freshwater environments. Some species are brightly colored, and there is great variety in body shape. They reproduce both sexually and asexually.

Classification

Hooper and van Soest give the following classification of demosponges into orders:^[1]

• Subclass Homoscleromorpha Bergquist, 1978
  • Homosclerophorida Dendy, 1905
• Subclass Tetractinomorpha
  • Astrophorida Sollas, 1888
  • Chondrosida Boury-Esnault & Lopès, 1985
  • Hadromerida Topsent, 1894
  • Lithistida Sollas, 1888
  • Spirophorida Bergquist & Hogg, 1969
• Subclass Ceractinomorpha Levi, 1953
  • Agelasida Verrill, 1907
  • Dendroceratida Minchin, 1900
  • Dictyoceratida Minchin, 1900
  • Halichondrida Gray, 1867
  • Halisarcida Bergquist, 1996
  • Haplosclerida Topsent, 1928
  • Poecilosclerida Topsent, 1928
  • Verongida Bergquist, 1978
  • Verticillitida Termier & Termier, 1977

However, molecular evidence suggests that the Homoscleromorpha may not belong in this class and that other classifications may need to be revised.^[2]

References

1. ^  J. N. A. Hooper and R. W. M. van Soest (2002). "Class Demospongiae Sollas, 1885", Systema Porifera. A guide to the classification of sponges. New York, Boston, Dordrecht, London, Moscow: Kluwer Academic/Plenum Publishers. 
2. ^  C. Borchiellini, C. Chombard, M. Manuel, E. Alivon, J. Vacelet, and N. Boury-Esnault (2004). "Molecular phylogeny of Demospongiae: implications for classification and scenarios of character evolution". Mol. Phylogenet. Evol. 32 (3): 823–37. doi:10.1016/j.ympev.2004.02.021. 

• Barnes, R.S.K. et al (2001). The Invertebrates: A Synthesis. Oxford: Blackwell Science. ISBN 0-632-04761-5