ParaHoxozoa

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ParaHoxozoa
Temporal range: 605.2 –0 
Ma
 Ediacaran-Present
Diversity of parahoxozoans
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Subkingdom: Eumetazoa
Clade: ParaHoxozoa
Ryan et al., 2010
Taxa

ParaHoxozoa (or Parahoxozoa) is a

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]

Phylogeny

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

  Choanozoa  

 Choanoflagellata

  
Animalia
  

 Ctenophora

 

Porifera

  Parahoxozoa  

 Placozoa

  Planulozoa  
     

 Cnidaria

 Bilateria

  
  
  
  

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
]

Characteristics

Parahoxozoa was defined by the presence of several gene (sub)classes (HNF, CUT, PROS, ZF, CERS, K50, S50-PRD), as well as

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

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 developed before the Cnidaria–Bilateria radiation as well.[23]

ParaHoxozoa/Parahoxozoa taxonomy

The Parahoxozoa has 3 different types of phyla that includes

bilaterians
.

Placozoans

These are placozoans (e.g.

Cladtertia collaboinventa
) are a phylum of this tiny creature.

Cnidarians

Cnidarians (e.g.

cnidocytes
.

Bilaterians

Many species of bilterians (e.g.

Pufferfish, Stingray, Mantaray
,

References

  1. PMID 20920347
    .
  2. PMID 20378579
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  3. PMID 29199080
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  4. S2CID 4560353
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  5. PMID 25902535
    .
  6. PMID 26596625
    .
  7. PMID 28993654
    .
  8. PMID 24847885
    .
  9. PMID 24337300
    .
  10. PMID 31879283
    .
  11. ^
    ISBN 978-0-691-19706-7
    .
  12. S2CID 205241127
    .
  13. S2CID 18994676
    .
  14. PMID 30859199
    .
  15. ISSN 1463-6409
    .
  16. S2CID 205247296
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  17. PMID 27568594
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  18. S2CID 5170702
    .
  19. PMID 18192186
    .
  20. PMID 28974637
    .
  21. S2CID 16870420
    .
  22. S2CID 86185156
    .
  23. PMID 21669750
    .
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