Benthozoa

{{Short description|Clade of animals}} {{use dmy dates|date=March 2026}} {{Automatic taxobox | image = | taxon = Benthozoa | authority = Erives and Fritzsch, 2019 | subdivision_ranks = Clades | subdivision = * Porifera * ParaHoxozoa | synonyms = Myriazoa {{small|Schultz ''et al''., 2023}} }} The '''Benthozoa''' or '''Myriazoa'''<ref name="Schultz2023"> {{cite journal |last1=Schultz |first1=Darrin T. |last2=Haddock |first2=Steven H.D. |last3=Bredeson |first3=Jessen V. |last4=Green |first4=Richard E. |last5=Simakov |first5=Oleg |last6=Rokhsar |first6=Daniel S. |date=2023-05-17 |title=Ancient gene linkages support ctenophores as sister to other animals |journal=Nature |volume=618 |issue=7963 |pages=110–117 |doi=10.1038/s41586-023-05936-6 |pmid=37198475 |issn=0028-0836 |pmc=10232365 |bibcode=2023Natur.618..110S |url=https://rdcu.be/dcJSY |lang=en }} </ref> are a proposed crown clade including all living animals except Ctenophora.<ref name="Erives2020"> {{cite journal |last1=Erives |first1=Albert |last2=Fritzsch |first2=Bernd |title=A Screen for Gene Paralogies Delineating Evolutionary Branching Order of Early Metazoa |journal=G3 Genes|Genomes|Genetics |date=2020 |volume=10 |issue=2 |pages=811–826 |doi=10.1534/g3.119.400951 |pmid=31879283 |biorxiv=10.1101/704551 |language=en |pmc=7003098 }} </ref>

This proposal is an alternative to the Porifera-sister hypothesis in which Porifera (sea sponges) are the sister group to Eumetazoa (all other animals, including Ctenophora).<ref name="Nielsen2019">{{Cite journal |last=Nielsen |first=Claus |date=2019 |title=Early animal evolution: a morphologist's view |journal=Royal Society Open Science |language=en |volume=6 |issue=7 |article-number=190638 |doi=10.1098/rsos.190638 |doi-access=free |issn=2054-5703 |pmc=6689584 |pmid=31417759 |bibcode=2019RSOS....690638N }}</ref>

== Evolution == The group name Benthozoa comes from the hypothesized transition of its early ancestors from an entirely holopelagic life cycle to one with a benthic adult form.<ref name="Erives2020" />

Schultz ''et al''. proposed the alternative name Myriazoa (meaning "numerous animals") as a replacement that avoids assumptions about evolutionary novelties.<ref name="Schultz2023" /> They do not recognize morphological characters uniting Porifera to the Parahoxozoa, but found that patterns of gene distributions across chromosomes strongly support the occurrence of an irreversible group of changes in the shared ancestor of Porifera and Parahoxozoa but not in the ancestor they share with Ctenophora.<ref name="Schultz2023" />

Ctenophores share multiple features with Parahoxozoa, including extracellular digestion, germ layers and a nervous system. The absence of these features in sponges implies either convergence between the two other groups, or their loss in Porifera.<ref name="Nielsen2019" />{{clear}}

The following cladogram is adapted from figure 4g of Schultz ''et al.'' (2023),<ref name=Schultz2023 /> although Nielsen (2019) notes that whether Cnidaria is considered sister to Placozoa or Bilateria varies among recent phylogenetic analyses.<ref name=Nielsen2019 /> {{clade |style=font-size:70%; line-height:90% |label1=Choanozoa |sublabel1=950 mya |1={{clade |1=Choanoflagellata 60 px |label2=Animalia |sublabel2=760 mya |2={{clade |label1= |1=Ctenophora 60 px |label2='''Benthozoa''' / |sublabel2='''Myriazoa''' |2={{clade |1=Porifera 60 px |label2=Parahoxozoa |2={{clade |1={{clade |label1= |1=Placozoa 60 px |2=Cnidaria 60 px }} |2=Bilateria 60 px 60 px }} }} }} }} }}

==References== {{reflist|25em}}

Category:Animal taxa