 | This article needs additional citations for verification. (June 2007) |
| Mesozoa | |
|---|---|
| |
| Dicyema macrocephalum | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Subkingdom: | Eumetazoa |
| Clade: | ParaHoxozoa |
| Clade: | Bilateria |
| Clade: | Nephrozoa |
| (unranked): | Protostomia |
| (unranked): | Spiralia |
| Clade: | Platytrochozoa |
| (unranked): | Mesozoa van Beneden, 1876 |
| Phyla | |
The Mesozoa are minuscule, worm-like parasites of marine invertebrates. Generally, these tiny, elusive creatures consist of a somatoderm (outer layer) of ciliated cells surrounding one or more reproductive cells.
A 2017 study recovered Mesozoa as a monophyletic group that emerged in the Lophotrochozoa as sister of the Rouphozoa.[1]
Some workers previously classified Mesozoa as the sole phylum of the lonely subkingdom Agnotozoa. Cavalier-Smith argued that at least some of the mesozoans are in fact protistans, not animals.[2]
In the 19th century, the Mesozoa were a wastebasket taxon for multicellular organisms which lacked the invaginating gastrula which was thought to define the Metazoa.[3]
- ^ Lu, Tsai-Ming; Kanda, Miyuki; Satoh, Noriyuki; Furuya, Hidetaka (2017-05-29). "The phylogenetic position of dicyemid mesozoans offers insights into spiralian evolution". Zoological Letters. 3: 6. doi:10.1186/s40851-017-0068-5. ISSN 2056-306X. PMC 5447306. PMID 28560048.
- ^ Hanelt, B.; Van Schyndel, D.; Adema, C.M.; Lewis, L.A.; Loker, E.S. (November 1996). "The Phylogenetic Position of Rhopaluva ophiocomae (Orthonectida) Based on 18s Ribosomal DNA Sequence Analysis" (PDF). Molecular Biology and Evolution. 13 (9): 1187–1191. doi:10.1093/oxfordjournals.molbev.a025683. PMID 8896370. Archived (PDF) from the original on 2022-10-09. Retrieved 2013-03-14.
- ^ Syed, Tareq; Schierwater, Bernd (December 2002). "Trichoplax adhaerens: discovered as a missing link, forgotten as a hydrozoan, re-discovered as a key to metazoan evolution". Vie et Milieu. 52 (4): 177–187.