Phosphatase Glossary: Metazoa
Metazoans are the same as animals, a group of multi-cellular eukaryotes. They are a subset of the Holozoans, which includes a few unicellular groups such as choanoflagellates. Within the Metazoa, the earliest branching lineages are sponges (they may be monophyletic or polyphyletic), which have little tissue structure. Eumetazoa ("true metazoans") consist of all metazoans other than sponges.