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Temporal range: 580–0 Ma Ediacaran-Present
Diversity of parahoxozoans
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Subkingdom: Eumetazoa
Clade: ParaHoxozoa
Ryan et al., 2010

ParaHoxozoa (or Parahoxozoa) is a clade of animals that consists of Bilateria, Placozoa, and Cnidaria.[1] The relationship of this clade relative to the two other animal lineages Ctenophora and Porifera is debated. Some phylogenomic studies have presented evidence supporting Ctenophora as the sister to Parahoxozoa and Porifera as the sister group to the rest of animals (e.g. [2][3][4]). Other studies have presented evidence supporting Porifera as the sister to Parahoxozoa and Ctenophora as the sister group to the rest of animals (e.g. [5][6][7]), finding that nervous systems either evolved independently in ctenophores and parahoxozoans,[8] or were secondarily lost in poriferans.[9] If ctenophores are taken to have diverged first, Eumetazoa is sometimes used as a synonym for ParaHoxozoa.[10]


The tree below, which is congruent with the vast majority of these phylogenomic studies, conveys this uncertainty with a polytomy.












ParaHoxozoa or Parahoxozoa

Though "ParaHox" genes are usually referred to in CamelCase and the original paper that named the clade used "ParaHoxozoa", the single initial capital format "Parahoxozoa" has also come to be used in the literature,[11] as CamelCase is not standard in zoological nomenclature.[citation needed]


Parahoxozoa was defined by the presence of several gene (sub)classes (HNF, CUT, PROS, ZF, CERS, K50, S50-PRD), as well as Hox/ParaHox-ANTP from which the name of this clade originated. It was later proposed[12][13] and contested[14] that a gene of the same class (ANTP) as the Hox/ParaHox, the NK gene and the Cdx Parahox gene, is also present in Porifera, the sponges. Regardless of whether a ParaHox gene is ever definitively identified, Parahoxozoa, as originally defined, is monophyletic and therefore continues to be used as such.[15]

Planula-acoel, triploblasty, and bilaterian similarities

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The original Bilateria are hypothesized to be a bottom dwelling worm with a single body opening.[16] A through-gut may already have developed with the Ctenophora however.[17] The through-gut may have developed from the corners of a single opening with lips fusing. E.g. Acoela resemble the planula larvae of some Cnidaria, which exhibit some bilaterian symmetry. They are vermiform, just as the cnidarian Buddenbrockia is.[18][19][20] Placozoans have been noted to resemble planula.[21] Usually, "Planulozoa" refers to a Cnidaria–Bilateria clade to the exclusion of Placozoa, but not necessarily.[11] In the other case, when including all three lineages, it appears synonymous with Parahoxozoa.[22] Triploblasty may have developed before the Cnidaria–Bilateria radiation too.[23]


The Parahoxozoa has 3 different types of phyla that includes placozoans, cnidarians, and bilaterians.


These are placozoans (e.g. Polyplacotoma mediterranea, Trichoplax adhaerens, Hoilungia hongkongensis, and Cladtertia collaboinventa) are a phylum of this tiny creature.


Cnidarians (e.g. Jellyfish, Coral, Sea anemone, Stalked jellyfish, Hydra, Box jellyfish, and Sea fans) have stinging cells called cnidocytes.


Many species of bilterians (e.g. Eels, Flounders, Common dab, Sole (fish), Pufferfish, Stingray, Mantaray,


  1. ^ Ryan, Joseph F.; Pang, Kevin; Mullikin, James C.; Martindale, Mark Q.; Baxevanis, Andreas D. (2010-10-04). "The homeodomain complement of the ctenophore Mnemiopsis leidyi suggests that Ctenophora and Porifera diverged prior to the Parahoxozoa". EvoDevo. 1 (1): 9. doi:10.1186/2041-9139-1-9. ISSN 2041-9139. PMC 2959044. PMID 20920347.
  2. ^ Pick, K. S.; Philippe, H.; Schreiber, F.; Erpenbeck, D.; Jackson, D. J.; Wrede, P.; Wiens, M.; Alie, A.; Morgenstern, B.; Manuel, M.; Worheide, G. (2010). "Improved Phylogenomic Taxon Sampling Noticeably Affects Nonbilaterian Relationships". Molecular Biology and Evolution. 27 (9): 1983–1987. doi:10.1093/molbev/msq089. ISSN 0737-4038. PMC 2922619. PMID 20378579.
  3. ^ 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. 6 (24): 3864–3870.e4. Bibcode:2017CBio...27E3864F. doi:10.1016/j.cub.2017.11.008. hdl:11572/302898. PMID 29199080.
  4. ^ 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" (PDF). Current Biology (Submitted manuscript). 27 (7): 958–967. Bibcode:2017CBio...27..958S. doi:10.1016/j.cub.2017.02.031. ISSN 0960-9822. PMID 28318975. S2CID 4560353.
  5. ^ Whelan, Nathan V.; Kocot, Kevin M.; Moroz, Leonid L.; Halanych, Kenneth M. (2015). "Error, signal, and the placement of Ctenophora sister to all other animals". Proceedings of the National Academy of Sciences. 112 (18): 5773–5778. Bibcode:2015PNAS..112.5773W. doi:10.1073/pnas.1503453112. ISSN 0027-8424. PMC 4426464. PMID 25902535.
  6. ^ Borowiec, Marek L.; Lee, Ernest K.; Chiu, Joanna C.; Plachetzki, David C. (2015). "Extracting phylogenetic signal and accounting for bias in whole-genome data sets supports the Ctenophora as sister to remaining Metazoa". BMC Genomics. 16 (1): 987. doi:10.1186/s12864-015-2146-4. ISSN 1471-2164. PMC 4657218. PMID 26596625.
  7. ^ Whelan, Nathan V.; Kocot, Kevin M.; Moroz, Tatiana P.; Mukherjee, Krishanu; Williams, Peter; Paulay, Gustav; Moroz, Leonid L.; Halanych, Kenneth M. (2017). "Ctenophore relationships and their placement as the sister group to all other animals". Nature Ecology & Evolution. 1 (11): 1737–1746. Bibcode:2017NatEE...1.1737W. doi:10.1038/s41559-017-0331-3. ISSN 2397-334X. PMC 5664179. PMID 28993654.
  8. ^ Moroz, Leonid L.; Kocot, Kevin M.; Citarella, Mathew R.; Dosung, Sohn; Norekian, Tigran P.; Povolotskaya, Inna S.; Grigorenko, Anastasia P.; Dailey, Christopher; Berezikov, Eugene; Buckley, Katherine M.; Ptitsyn, Andrey; Reshetov, Denis; Mukherjee, Krishanu; Moroz, Tatiana P.; Bobkova, Yelena; Yu, Fahong; Kapitonov, Vladimir V.; Jurka, Jerzy; Bobkov, Yuri V.; Swore, Joshua J.; Girardo, David O.; Fodor, Alexander; Gusev, Fedor; Sanford, Rachel; Bruders, Rebecca; Kittler, Ellen; Mills, Claudia E.; Rast, Jonathan P.; Derelle, Romain; Solovyev, Victor V.; Kondrashov, Fyodor A.; Swalla, Billie J.; Sweedler, Jonathan V.; Rogaev, Evgeny I.; Halanych, Kenneth M.; Kohn, Andrea B. (2014). "The ctenophore genome and the evolutionary origins of neural systems". Nature. 510 (7503): 109–114. Bibcode:2014Natur.510..109M. doi:10.1038/nature13400. ISSN 0028-0836. PMC 4337882. PMID 24847885.
  9. ^ Ryan, J. F.; Pang, K.; Schnitzler, C. E.; Nguyen, A.-D.; Moreland, R. T.; Simmons, D. K.; Koch, B. J.; Francis, W. R.; Havlak, P.; Smith, S. A.; Putnam, N. H.; Haddock, S. H. D.; Dunn, C. W.; Wolfsberg, T. G.; Mullikin, J. C.; Martindale, M. Q.; Baxevanis, A. D. (2013). "The Genome of the Ctenophore Mnemiopsis leidyi and Its Implications for Cell Type Evolution". Science. 342 (6164): 1242592. doi:10.1126/science.1242592. ISSN 0036-8075. PMC 3920664. PMID 24337300.
  10. ^ Erives, Albert; Fritzsch, Bernd (2020). "A Screen for Gene Paralogies Delineating Evolutionary Branching Order of Early Metazoa". G3: Genes, Genomes, Genetics. 10 (2): 811–826. doi:10.1534/g3.119.400951. ISSN 2160-1836. PMC 7003098. PMID 31879283.
  11. ^ a b Giribet, Gonzalo; Edgecombe, Gregory D. (2020-03-03). The Invertebrate Tree of Life. Princeton University Press. p. 46. doi:10.1515/9780691197067-007. ISBN 978-0-691-19706-7.
  12. ^ Fortunato, Sofia A. V.; Adamski, Marcin; Ramos, Olivia Mendivil; Leininger, Sven; Liu, Jing; Ferrier, David E. K.; Adamska, Maja (2014-10-30). "Calcisponges have a ParaHox gene and dynamic expression of dispersed NK homeobox genes". Nature. 514 (7524): 620–623. Bibcode:2014Natur.514..620F. doi:10.1038/nature13881. hdl:10023/6597. ISSN 0028-0836. PMID 25355364. S2CID 205241127.
  13. ^ Larroux, Claire; Fahey, Bryony; Degnan, Sandie M.; Adamski, Marcin; Rokhsar, Daniel S.; Degnan, Bernard M. (1996). "The NK Homeobox Gene Cluster Predates the Origin of Hox Genes". Current Biology. 17 (8): 706–710. doi:10.1016/j.cub.2007.03.008. PMID 17379523. S2CID 18994676.
  14. ^ Pastrana, Claudia C.; DeBiasse, Melissa B.; Ryan, Joseph F. (2019). "Sponges lack ParaHox genes". Genome Biology and Evolution. 11 (4): 1250–1257. doi:10.1093/gbe/evz052. PMC 6486804. PMID 30859199.
  15. ^ 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.
  16. ^ Cannon, Johanna Taylor; Vellutini, Bruno Cossermelli; Smith, Julian; Ronquist, Fredrik; Jondelius, Ulf; Hejnol, Andreas (2016). "Xenacoelomorpha is the sister group to Nephrozoa". Nature (Submitted manuscript). 530 (7588): 89–93. Bibcode:2016Natur.530...89C. doi:10.1038/nature16520. PMID 26842059. S2CID 205247296.
  17. ^ Browne, William E.; Amemiya, Chris T.; Swalla, Billie J.; Warren, Kaitlyn J.; Vandepas, Lauren E.; Presnell, Jason S. (2016-10-24). "The Presence of a Functionally Tripartite Through-Gut in Ctenophora Has Implications for Metazoan Character Trait Evolution". Current Biology. 26 (20): 2814–2820. Bibcode:2016CBio...26.2814P. doi:10.1016/j.cub.2016.08.019. ISSN 0960-9822. PMID 27568594.
  18. ^ Jiménez-Guri, Eva; Philippe, Hervé; Okamura, Beth; Holland, Peter W. H. (2007-07-06). "Buddenbrockia Is a Cnidarian Worm". Science. 317 (5834): 116–118. Bibcode:2007Sci...317..116J. doi:10.1126/science.1142024. ISSN 0036-8075. PMID 17615357. S2CID 5170702.
  19. ^ 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 2615819. PMID 18192186.
  20. ^ Genikhovich, Grigory; Technau, Ulrich (2017-10-01). "On the evolution of bilaterality". Development. 144 (19): 3392–3404. doi:10.1242/dev.141507. ISSN 0950-1991. PMID 28974637.
  21. ^ Syed, Tareq; Schierwater, Bernd (2002). "The evolution of the placozoa: A new morphological model". Senckenbergiana Lethaea. 82 (1): 315–324. doi:10.1007/bf03043791. ISSN 0037-2110. S2CID 16870420.
  22. ^ Wallberg, Andreas; Thollesson, Mikael; Farris, James S.; Jondelius, Ulf (2004). "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 0748-3007. PMID 34892961. S2CID 86185156.
  23. ^ Boero, F.; Schierwater, B.; Piraino, S. (2007-06-01). "Cnidarian milestones in metazoan evolution". Integrative and Comparative Biology. 47 (5): 693–700. doi:10.1093/icb/icm041. ISSN 1540-7063. PMID 21669750.
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