All other animals are grouped into a subkingdom called Eumetazoa (true animals). All eumetazoans have tissues and organs, except for one phylum, Myxozoa, which have regressed to a single-celled form. | All other animals are grouped into a subkingdom called Eumetazoa (true animals). All eumetazoans have tissues and organs, except for one phylum, Myxozoa, which have regressed to a single-celled form. |