Eumetazoa

Summary

Eumetazoa, also known as Epitheliozoa or Histozoa, is a proposed basal animal subkingdom as a sister group of Porifera (sponges). The basal eumetazoan clades are the Ctenophora and the ParaHoxozoa. Placozoa is now also seen as an eumetazoan clade in the ParaHoxozoa, based on genetic data. The subkingdom Parazoa comprises the sister taxa, which includes primarily Porifera. The competing hypothesis is the Myriazoa clade, which states Ctenophora diverged earlier than Porifera, who instead would make up a clade with ParaHoxozoa, implying either sponges lost complexity or Ctenophores developed complexity independently, and maybe even a mix of both processes. As far as May 2026, this question remains unresolved and the dispute may became combative, with some scientists deciding to not participate into the debate.