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 Chrysaora fuscescens
taxon links [up-->]Placozoa [up-->]Cnidaria [up-->]Porifera [up-->]Ctenophora [up-->]Myxozoa [up-->]Bilateria Not MonophyleticPhylogenetic position of group is uncertain[down<--]Eukaryotes Interpreting the tree
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This tree diagram shows the relationships between several groups of organisms.

The root of the current tree connects the organisms featured in this tree to their containing group and the rest of the Tree of Life. The basal branching point in the tree represents the ancestor of the other groups in the tree. This ancestor diversified over time into several descendent subgroups, which are represented as internal nodes and terminal taxa to the right.

example of a tree diagram

You can click on the root to travel down the Tree of Life all the way to the root of all Life, and you can click on the names of descendent subgroups to travel up the Tree of Life all the way to individual species.

For more information on ToL tree formatting, please see Interpreting the Tree or Classification. To learn more about phylogenetic trees, please visit our Phylogenetic Biology pages.

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Containing group: Eukaryotes

Other Names for Animals


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Budd, G. E. 2008. The earliest fossil record of the animals and its significance. Philosophical Transactions of the Royal Society Series B 363(1496):1425-1434.

Carroll, S. B., J. K. Grenier, and S. D. Weatherbee. 2001. From DNA to Diversity. Molecular Genetics and the Evolution of Animal Design. Blackwell Science, Malden, Massachusetts.

Cavalier-Smith, T., M. T. E. P. Allsopp, E. E. Chao, N. Boury-Esnault, and J. Vacelet. 1996. Sponge phylogeny, animal monophyly, and the origin of the nervous system: 18S rRNA evidence. Canadian Journal of Zoology 74:2031-2045.

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Collins, A. G. 1998. Evaluating multiple alternative hypotheses for the origin of Bilateria: An analysis of 18S rRNA molecular evidence. Proceedings of the National Academy of Sciences (U.S.A.) 95:15458-15463.

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Eernisse, D. J. and K. J. Peterson. 2004. The history of animals. Pages 197-208 in Assembling the Tree of Life, J. Cracraft and M. J. Donoghue, eds. Oxford University Press, New York.

Ender, A. and B. Schierwater. 2003. Placozoa are not derived cnidarians: Evidence from molecular morphology. Molecular Biology and Evolution 20(1):130-134.

Erwin, D. H. 1993. The origin of metazoan development: A palaeobiological perspective. Biological Journal of the Linnean Society 50: 255-274.

Ferrier, D. E. K. and P. W. H. Holland. 2001. Ancient origin of the Hox gene cluster. Nature Reviews Genetics 2:33-38.

Finnerty, J. R., K. Pang, P. Burton, D. Paulson, and M. Q. Martindale. 2004. Origins of bilateral symmetry; Hox and dpp expression in a sea anemone. Science 304:1335-37.

Giribet, G. 2002. Current advances in the phylogenetic reconstruction of metazoan evolution. A new paradigm for the Cambrian explosion? Molecular Phylogenetics and Evolution 24:345-357.

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Haen, K. M., B. F. Lang, S. A. Pomponi, and D. V. Lavrov. 2007. Glass sponges and bilaterian animals share derived mitochondrial genomic features: a common ancestry or parallel evolution? Molecular Biology and Evolution 24(7):1518 - 1527.

Halanych, K. 2004. The new view of animal phylogeny. Annual Review of Ecology, Evolution, and Systematics 35:229-256.

Hanelt B., D. VanSchyndel, C. M. Adema, L. A. Lewis, E. S. Loker. 1996. The phylogenetic position of Rhopalura ophiocomae (Orthonectida) based on 18S ribosomal DNA sequence analysis. Molecular Biology and Evolution 13:1187-1191.

Jenner, R. A. 2004. The scientific status of metazoan cladistics: why current research practice must change. Zoologica Scripta 33(4):293-310.

Jenner, R. A. 2004. When molecules and morphology clash: Reconciling conflicting phylogenies of the Metazoa by considering secondary character loss. Evolution & Development 6(5):372-378.

Jenner, R. A. and D. T. J. Littlewood. 2008. Problematica old and new. Philosophical Transactions of the Royal Society Series B 363(1496):1503-1512.

Jenner, R. A. and F. R. Schram. 1999. The grand game of metazoan phylogeny: rules and strategies. Biological Reviews 74:121-142.

Jiménez-Guri, E., H. Philippe, B. Okamura, P. W. H. Holland. 2007. Buddenbrockia is a cnidarian worm. Science 317(5834):116-118.

Kamm, K., B. Schierwater, W. Jakob, S. L. Dellaporta, and D. J. Miller. 2006. Axial patterning and diversification in the Cnidaria predate the Hox system. Current Biology 16:920-926.

Kim, J., W. Kim, and C. W. Cunningham. 1999. A new perspective on lower metazoan relationships from 18S rDNA sequences. Molecular Biology and Evolution 16:423-427.

Knoll, A. H. and S. B. Carroll. 1999. Early animal evolution: emerging views from comparative biology and geology. Science 284:2129-2137.

Kruse, M., S. P. Leys, I. M. Mueller, and W. E. G. Mueller. 1998. Phylogenetic position of the hexactinellida within the phylum porifera based on the amino acid sequence of the protein kinase C from Rhabdocalyptus dawsoni. Journal of Molecular Evolution 46:721-728.

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Martindale, M. Q., J. R. Finnerty, and J. Q. Henry. 2002. The Radiata and the evolutionary origins of the bilaterian body plan. Molecular Phylogenetics and Evolution 24:358-365.

Matus, D. Q., K. Pang, H. Marlow, C. W. Dunn, G. H. Thomsen, and M. Q. Martindale. 2006. Molecular evidence for deep evolutionary roots of bilaterality in animal development. Proceedings of the National Academy of Sciences (USA) 103(30):11195-11200.

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Monteiro, A. S., B. Okamura, and P. W. H. Holland. 2002. Orphan worm finds a home: Buddenbrockia is a Myxozoan. Molecular Biology and Evolution 19:968-971.

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Nielsen, C., N. Scharff, and D. Eibye-Jacobsen. 1996. Cladistic analyses of the animal kingdom. Biological Journal of the Linnean Society 57:385-410.

Okamura, B., A. Curry, T. S. Wood, and E. U. Canning. 2002. Ultrastructure of Buddenbrockia identifies it as a myxozoan and verifies the bilaterian origin of the Myxozoa. Parasitology 124:215-223.

Peterson, K. J. and N. J. Butterfield. 2005. Origin of the Eumetazoa: Testing ecological predictions of molecular clocks against the Proterozoic fossil record. Proceedings of the National Academy of Sciences (USA) 102(27):9547-9552.

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Peterson, K. J. and D. J. Eernisse. 2001. Animal phylogeny and the ancestry of bilaterians: inferences from morphology and 18S rDNA gene sequences. Evolution & Development 3:170-205.

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Information on the Internet

Metazoa in Special Habitats

Fossil Metazoa

Title Illustrations
Click on an image to view larger version & data in a new window
Click on an image to view larger version & data in a new window
Scientific Name Macaca radiata
Location B R Hills,Karnataka, INDIA
Specimen Condition Live Specimen
Source Curious Look
Source Collection Flickr
Image Use creative commons This media file is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs License - Version 2.0.
Copyright © 2008 Supriya 'n' Subharghya
Chrysaora fuscescens
Scientific Name Chrysaora fuscescens
Location Ripley Aquarium, Myrtle Beach, South Carolina, USA--native to Pacific Coast
Comments Class: Scyphozoa, Order: Semaeostomeae, Family: Pelagiidae Common name: Sea Nettle, or Pacific Sea Nettle
Specimen Condition Live Specimen
Identified By Ripley Aquarium, Myrtle Beach, South Carolina
Behavior Captive specimen
Life Cycle Stage medusa
View lateral
Size bell circa 10 cm diameter
Image Use creative commons This media file is licensed under the Creative Commons Attribution-NonCommercial License - Version 2.5.
Copyright © 2007 Patrick Coin
Scientific Name Scaphinotus petersi
Location USA AZ Yavapai County
Source Scaphinotus petersi - ground beetle
Copyright © Alex Wild
Scientific Name Ctenophora
Location captive at Texas State Aquarium
Specimen Condition Live Specimen
Copyright © Greg and Marybeth Dimijian
Scientific Name Haliclona
Creator David Remsen
Copyright © 1995 Marine Biological Laboratory, Woods Hole
About This Page

Page: Tree of Life Animals. Metazoa. The TEXT of this page is licensed under the Creative Commons Attribution-NonCommercial License - Version 3.0. Note that images and other media featured on this page are each governed by their own license, and they may or may not be available for reuse. Click on an image or a media link to access the media data window, which provides the relevant licensing information. For the general terms and conditions of ToL material reuse and redistribution, please see the Tree of Life Copyright Policies.

Citing this page:

Tree of Life Web Project. 2002. Animals. Metazoa. Version 01 January 2002 (temporary). http://tolweb.org/Animals/2374/2002.01.01 in The Tree of Life Web Project, http://tolweb.org/

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For a more detailed explanation of the different ToL page types, have a look at the Structure of the Tree of Life page.

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