Holozoa
Holozoa is a group of living things that includes animals, and some single-celled relatives of animals. It excludes fungi.[1][2][3][4] Holozoa is also an old name for the tunicate genus Distaplia.[5]
| Holozoa | |
|---|---|
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| Orange elephant ear sponge, Agelas clathrodes, in foreground. Two corals in the background: a sea fan, Iciligorgia schrammi, and a sea rod, Plexaurella nutans. | |
Scientific classification 
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| (unranked): | Unikonta |
| (unranked): | Obazoa |
| (unranked): | Opisthokonta |
| (unranked): | Holozoa Lang et al., 2002 |
| Subgroups | |
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Holozoa is a clade: a group of plants or animals with a common ancestor. It has all organisms close to animals.[6]
An example of a well-known holozoan is the choanoflagellate, which looks a lot like the cells of a sponge. Proterospongia is an example of a choanoflagellate that might give clues as to how sponges evolved.
Evolution
The phylogenic tree (evolution tree) below shows how clades broke into newer clades. This includes Holozoa.
| Opisthokonta |
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Holozoa Media
Nuclearia_sp_Nikko_(cropped)
Linear_arrangement_of_ascospores_in_the_asci_of_the_fungus_Sordaria_macrospora_Cropped
DIC microscopy
General view of flagellated cell (scanning electron microscopy, SEM) of Syssomonas multiformis
ctenophora
Unicellular holozoans do not go through animal embryonic development, but they display developmental processes using similar molecules. An actomyosin network controls the cellularization of both an ichthyosporean coenocyte (A) and a fruit fly blastoderm (B).
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References
- ↑ Do we need many genes for phylogenetic inference?. Biochemistry Mosc. 72 (12) (December 2007). p. 1313–23. doi:10.1134/S000629790712005X.
- ↑ The closest unicellular relatives of animals. Curr. Biol. 12 (20) (October 2002). p. 1773–8. doi:10.1016/S0960-9822(02)01187-9.
- ↑ Shalchian-Tabrizi, Kamran. Multigene phylogeny of choanozoa and the origin of animals. PLOS ONE 3 (5) (7 May 2008). p. e2098. doi:10.1371/journal.pone.0002098.
- ↑ The RJL family of small GTPases is an ancient eukaryotic invention probably functionally associated with the flagellar apparatus. Gene 442 (1–2) (August 2009). p. 63–72. doi:10.1016/j.gene.2009.04.011.
- ↑ Tatiàn, Marcos. Ascidians (Tunicata, Ascidiacea): species distribution along the Scotia Arc. Scientia Marina 69 (suppl. 2) (2005). p. 205–214. doi:10.3989/scimar.2005.69s2205.
- ↑ Steenkamp, Emma T.. The Protistan Origins of Animals and Fungi. Molecular Biology & Evolution 23 (1) (January 2006). p. 93–106. doi:10.1093/molbev/msj011.