Planulozoa is aclade which includes thePlacozoa,Cnidaria (corals and jellyfish) and theBilateria (all the more complex animals including worms, insects and vertebrates).[2][3] The designation Planulozoa may be considered a synonym toParaHoxozoa. Within Planulozoa, the Placozoa may be a sister of Cnidaria to the exclusion of Bilateria.[4][5][6][7] The clade excludesbasal animals such as theCtenophora (comb jellies),[8][9][3] andPorifera (sponges).[10][11][12] Although this clade was sometimes used to specify a clade of Cnidaria and Bilateria to the exclusion of Placozoa (against the original intention of its proposal), this is no longer favoured due to recent data (several 2018 studies) indicating a sister group relationship between Cnidaria and Placozoa.[13] However, a 2023 study supports Placozoa as sister to Cnidaria+Bilateria in several analyses.[14]
Thephylogenetic tree indicates approximately how many millions of years ago (mya) the lineages split. Here, Planulozoa is shown sans Placozoa.[15][16][17]
Planulozoa are associated with the emergence of the Zoc and ZF-NC gene domains.[18]
^Schuchert, Peter (1993-03-01). "Trichoplax adhaerens (Phylum Placozoa) has Cells that React with Antibodies Against the Neuropeptide RFamide".Acta Zoologica.74 (2):115–117.doi:10.1111/j.1463-6395.1993.tb01227.x.
^Syed, Tareq; Schierwater, Bernd (2002-06-01). "The evolution of the placozoa: A new morphological model".Senckenbergiana Lethaea.82 (1):315–324.doi:10.1007/bf03043791.ISSN0037-2110.S2CID16870420.
^Giribet, Gonzalo (2020).The invertebrate tree of life. Gregory D. Edgecombe. Princeton, New Jersey. p. 46.ISBN978-0-691-19706-7.OCLC1129197548.{{cite book}}: CS1 maint: location missing publisher (link)
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