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From Wikipedia, the free encyclopedia

Scientific classification e
Kingdom: Animalia
Subkingdom: Diploblast
Lankester, 1873

The diploblasts, or Eumetazoa, or Epitheliozoa, or Histozoa are a proposed basal Animal clade as sister of the Sponges.[1] They feature diploblasty, i.e. they have two germ layers.[2][3][4] Basal Diploblasts are the Ctenophora and the ParaHoxozoa, which, amongst others, cladistically include the Triploblasts/Bilateria as sister of the Cnidaria.[1] The way the germ layers themselves developed is disputed.[5] Eumetazoa are a very similar proposed clade, but they traditionally exclude the Placozoans, rendering them paraphyletic with recent evolutionary trees. The relative basal character of the diploblasts has long been recognized. The resolvement of the emergence of the triploblasts and other basal animals in the diploblast tree is still controversial, as well as the coherence of the diploblasts, even with the cladistic inclusion of the triploblasts. Some studies suggest Ctenophora to be more basal.

Evolutionary relationships

In a study of basal animals, the porifera were found to the basalmost extant animals, resulting in the cladogram below.[6][7][8][9][10][11][12] It is indicated approximately how many million years ago (Mya) the clades diverged into newer clades.[13][14]

Apoikozoa (950)



Animal (760)




Mertensia ovum.png




Medusae of world-vol03 fig360 Atolla chuni.jpg



Nephrozoa (650)


Cyprinus carpio3.jpg

Protostomes (610)


Long nosed weevil edit.jpg


Loligo forbesii.jpg




Diploblasts feature diploblasty. It was recently found that Ctenophora have a through-gut, as in most Bilateria and possibly some Cnidaria.[15][16][17] This is surprising because Placozoa, Cnidaria and Xenacoelomorpha do not, so it was presumed a through-gut only developed in Nephrozoa. The lack of anus-associated ortholog genes between Ctenophora and Nephrozoa perhaps suggests an independent convergent evolutionary scenario.


  1. ^ a b Chen, Justin; Jacox, Laura A.; Saldanha, Francesca; Sive, Hazel (2017-09-01). "Mouth development". Wiley Interdisciplinary Reviews: Developmental Biology. 6 (5): n/a–n/a. doi:10.1002/wdev.275. ISSN 1759-7692. 
  2. ^ Jonathan Eisen (2016-05-20). "BIS2C: Lecture 27: Having a Diploblast". 
  3. ^ Martindale, Mark Q.; Kourakis, Matthew J. (1999). "Hox clusters: Size doesn't matter". Nature. 399 (6738): 730–731. doi:10.1038/21530. 
  4. ^ Wallberg, Andreas; Thollesson, Mikael; Farris, James S.; Jondelius, Ulf (2004-12-01). "The phylogenetic position of the comb jellies (Ctenophora) and the importance of taxonomic sampling". Cladistics. 20 (6): 558–578. doi:10.1111/j.1096-0031.2004.00041.x. ISSN 1096-0031. 
  5. ^ "Diploblasts and triploblasts – Pharyngula". Retrieved 2017-08-31. 
  6. ^ Feuda, Roberto; Dohrmann, Martin; Pett, Walker; Philippe, Hervé; Rota-Stabelli, Omar; Lartillot, Nicolas; Wörheide, Gert; Pisani, Davide (2017). "Improved Modeling of Compositional Heterogeneity Supports Sponges as Sister to All Other Animals". Current Biology. 27: 3864–3870.e4. doi:10.1016/j.cub.2017.11.008. PMID 29199080. 
  7. ^ Pisani, Davide; Pett, Walker; Dohrmann, Martin; Feuda, Roberto; Rota-Stabelli, Omar; Philippe, Hervé; Lartillot, Nicolas; Wörheide, Gert (15 December 2015). "Genomic data do not support comb jellies as the sister group to all other animals". Proceedings of the National Academy of Sciences. 112 (50): 15402–15407. Bibcode:2015PNAS..11215402P. doi:10.1073/pnas.1518127112. ISSN 0027-8424. PMC 4687580Freely accessible. PMID 26621703. 
  8. ^ Simion, Paul; Philippe, Hervé; Baurain, Denis; Jager, Muriel; Richter, Daniel J.; Franco, Arnaud Di; Roure, Béatrice; Satoh, Nori; Quéinnec, Éric (3 April 2017). "A Large and Consistent Phylogenomic Dataset Supports Sponges as the Sister Group to All Other Animals". Current Biology. 27 (7): 958–967. doi:10.1016/j.cub.2017.02.031. ISSN 0960-9822. PMID 28318975. 
  9. ^ Giribet, Gonzalo (1 October 2016). "Genomics and the animal tree of life: conflicts and future prospects". Zoologica Scripta. 45: 14–21. doi:10.1111/zsc.12215. ISSN 1463-6409. 
  10. ^ Laumer, Christopher E.; Gruber-Vodicka, Harald; Hadfield, Michael G.; Pearse, Vicki B.; Riesgo, Ana; Marioni, John C.; Giribet, Gonzalo (2017-10-11). "Placozoans are eumetazoans related to Cnidaria". bioRxiv: 200972. doi:10.1101/200972. 
  11. ^ Eitel, Michael; Francis, Warren; Osigus, Hans-Jürgen; Krebs, Stefan; Vargas, Sergio; Blum, Helmut; Williams, Gray Argust; Schierwater, Bernd; Wörheide, Gert (2017-10-13). "A taxogenomics approach uncovers a new genus in the phylum Placozoa". bioRxiv: 202119. doi:10.1101/202119. 
  12. ^ Laumer, Christopher E.; Gruber-Vodicka, Harald; Hadfield, Michael G.; Pearse, Vicki B.; Riesgo, Ana; Marioni, John C.; Giribet, Gonzalo (2018-03-17). "Placozoa and Cnidaria are sister taxa". bioRxiv: 200972. doi:10.1101/200972. 
  13. ^ Peterson, Kevin J.; Cotton, James A.; Gehling, James G.; Pisani, Davide (2008-04-27). "The Ediacaran emergence of bilaterians: congruence between the genetic and the geological fossil records". Philosophical Transactions of the Royal Society of London B: Biological Sciences. 363 (1496): 1435–1443. doi:10.1098/rstb.2007.2233. ISSN 0962-8436. PMC 2614224Freely accessible. PMID 18192191. 
  14. ^ Parfrey, Laura Wegener; Lahr, Daniel J. G.; Knoll, Andrew H.; Katz, Laura A. (2011-08-16). "Estimating the timing of early eukaryotic diversification with multigene molecular clocks". Proceedings of the National Academy of Sciences. 108 (33): 13624–13629. doi:10.1073/pnas.1110633108. ISSN 0027-8424. PMC 3158185Freely accessible. PMID 21810989. 
  15. ^ Presnell, Jason S.; Vandepas, Lauren E.; Warren, Kaitlyn J.; Swalla, Billie J.; Amemiya, Chris T.; Browne, William E. (2016). "The Presence of a Functionally Tripartite Through-Gut in Ctenophora Has Implications for Metazoan Character Trait Evolution". Current Biology. 26 (20): 2814–2820. doi:10.1016/j.cub.2016.08.019. 
  16. ^ "Cnidarians–Radially Symmetric Bilaterians?". Nimravid's Weblog. 2008-03-28. Retrieved 2017-12-11. 
  17. ^ Baguñà, Jaume; Martinez, Pere; Paps, Jordi; Riutort, Marta (2008-04-27). "Back in time: a new systematic proposal for the Bilateria". Philosophical Transactions of the Royal Society B: Biological Sciences. 363 (1496): 1481–1491. doi:10.1098/rstb.2007.2238. ISSN 0962-8436. PMC 2615819Freely accessible. PMID 18192186. 
This page was last edited on 21 May 2018, at 17:23.
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