Parazoa

Parazoa Temporal range: Cryogenian – Holocene PreꞒ Ꞓ O S D C P T J K Pg N
Sponge
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Subkingdom:	Parazoa Grant & Todd, 1838
Taxa
Porifera ?†Archaeocyatha Placozoa
Synonyms
Enantiozoa, Delage 1892

Parazoa (Parazoa, gr. Παρα-, para, "next to", and ζωα, zoa, "animals") are a taxon with sub-kingdom category that is located at the base of the phylogenetic tree of the animal kingdom in opposition to the sub-kingdom Eumetazoa; they group together the most primitive forms, characterized by not having proper tissues or that, in any case, these tissues are only partially differentiated. They generally group a single phylum, Porifera, which lack muscles, nerves and internal organs, which in many cases resembles a cell colony rather than a multicellular organism itself. All other animals are eumetazoans, which do have differentiated tissues.

On occasion, Parazoa reunites Porifera with Archaeocyatha, a group of extinct sponges sometimes considered a separate phylum. In other cases, Placozoa is included, depending on the authors.