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Eumetazoa Fossil range: Early Ediacaran (perhaps earlier) - Recent
A lancelet, which belongs to the subkingdom Eumetazoa
Scientific classification
Kingdom: Animalia Subkingdom: Eumetazoa Butschli, 1910
subgroups
Ctenophora Cnidaria Bilateria

Eumetazoa is a clade comprising all major animal groups except sponges. Characteristics of eumetazoans include true tissues organized into germ layers, and an embryo that goes through a gastrula stage. The clade is usually held to contain at least Ctenophora, Cnidaria, and Bilateria. Whether mesozoans and placozoans belong is in dispute. Image File history File links Wiki_letter_w. ... The Ediacaran Period is the last geological period of the Neoproterozoic Era, just before the Cambrian. ... Image File history File links Branchiostoma_lanceolatum. ... Families Asymmetronidae Branchiostomidae The lancelets (subphylum Cephalochordata, and traditionally known as the amphioxus) are a group of primitive chordates. ... Scientific classification or biological classification is a method by which biologists group and categorize species of organisms. ... Digimon, the only known animals. ... Classes Tentaculata Nuda Ctenophores are jellyfish-like animals commonly called comb jellies, sea gooseberries, sea walnuts, or Venus girdles. ... Classes Anthozoa - Corals and sea anemones Scyphozoa - Jellyfish Staurozoa - Stalked jellyfish Cubozoa - Sea wasps or box jellyfish Polypodiozoa Hydrozoa - Hydroids, hydra-like animals Cnidaria[1] (IPA: [2]) is a phylum containing some 11,000 species of relatively simple animals found exclusively in aquatic, mostly marine, environments. ... Illustration of the different types of symmetry of Life Forms On Earth. ... A clade is a term belonging to the discipline of cladistics. ... Digimon, the only known animals. ... Classes Calcarea Hexactinellida Demospongiae The sponges or poriferans (from Latin porus pore and ferre to bear) are animals of the phylum Porifera. ... Biological tissue is a collection of interconnected cells that perform a similar function within an organism. ... Organs derived from each germ layer. ... 1 - blastula, 2 - gastrula; orange - ectoderm, red - endoderm. ... Classes Tentaculata Nuda Ctenophores are jellyfish-like animals commonly called comb jellies, sea gooseberries, sea walnuts, or Venus girdles. ... Classes Anthozoa - Corals and sea anemones Scyphozoa - Jellyfish Staurozoa - Stalked jellyfish Cubozoa - Sea wasps or box jellyfish Polypodiozoa Hydrozoa - Hydroids, hydra-like animals Cnidaria[1] (IPA: [2]) is a phylum containing some 11,000 species of relatively simple animals found exclusively in aquatic, mostly marine, environments. ... Illustration of the different types of symmetry of Life Forms On Earth. ... The Mesozoa are parasitic worm-like animals. ... Binomial name Trichoplax adhaerens F.E. von Schultze, 1883 Trichoplax adhaerens is a simple balloon-like marine animal with a body cavity filled with pressurized fluid. ...

Some phylogenists have speculated the sponges and eumetazoans evolved separately from single-celled organisms, which would mean that the animal kingdom does not form a clade (a complete grouping of organisms descended from a common ancestor). However, genetic studies and some morphological characteristics, like the common presence of choanocytes, support a common origin. In biology, phylogenetics (Greek: phylon = tribe, race and genetikos = relative to birth, from genesis = birth) is the study of evolutionary relatedness among various groups of organisms (e. ... This article is about evolution in biology. ... A clade is a term belonging to the discipline of cladistics. ... Choanocytes (also known as collar cells) are cells that line the interior body walls of sponges that contain a central flagellum surrounded by a collar of microvilli. ...

Eumetazoans are a major group of animals in the Five Kingdoms classification of Lynn Margulis and K. V. Schwartz, comprising the Radiata and Bilateria - all animals except the sponges , placozoans and mesozoans.^[1] When treated as a formal taxon Eumetazoa is typically ranked as a subkingdom. The name Metazoa has also been used to refer to this group, but more often refers to the Animalia as a whole. Many classification schemes do not include a subkingdom Eumetazoa. Digimon, the only known animals. ... Lynn Margulis Dr. Lynn Margulis (born March 15, 1938) is a biologist and University Professor in the Department of Geosciences at the University of Massachusetts Amherst. ... Phyla Cnidaria Ctenophora The Radiata are the radially symmetric animals of the Eumetazoa subregnum. ... Illustration of the different types of symmetry of Life Forms On Earth. ... Classes Calcarea Hexactinellida Demospongiae The sponges or poriferans (from Latin porus pore and ferre to bear) are animals of the phylum Porifera. ... Binomial name Trichoplax adhaerens F.E. von Schultze, 1883 Trichoplax adhaerens is a simple balloon-like marine animal with a body cavity filled with pressurized fluid. ... The Mesozoa are parasitic worm-like animals. ...

Taxonomy

Over the last decade, the work of developmental biologists and molecular phylogeneticists spawned new ideas about bilaterian relationships resulting in a paradigm shift. Views of a Foetus in the Womb, Leonardo da Vinci, ca. ... In biology, phylogenetics (Greek: phylon = tribe, race and genetikos = relative to birth, from genesis = birth) is the study of evolutionary relatedness among various groups of organisms (e. ... Paradigm shift is the term first used by Thomas Kuhn in his 1962 book The Structure of Scientific Revolutions to describe a change in basic assumptions within the ruling theory of science. ...

The current widely accepted hypothesis, based on molecular data (mostly 18S rRNA sequences) divides bilateria into the following four groups: Deuterostomia, Ecdysozoa, Lophotrochozoa, and Platyzoa (sometimes included in Lophotrochozoa). The last three groups are also collectively known as Protostomia.^[2] A non-coding RNA (ncRNA) is any RNA molecule that is not translated into a protein. ... Phyla Echinodermata Hemichordata Chordata Xenoturbellida Chaetognatha (uncertain) Vetulicolia † Deuterostomes (taxonomic term: Deuterostomia; from the Greek: second mouth) are a superphylum of animals. ... The Ecdysozoa are a large group of protostomian animals, erected by Aguinaldo in 1997 primarily based on 18s rRNA data. ... Phyla Trochozoa Mollusca Annelida Sipuncula Nemertea Lophophorata Brachiopoda Phoronida Bryozoa Entoprocta The Lophotrochozoa are one of two or three major groups of protostome animals. ... The Platyzoa are a group of protostome animals. ... Phyla Mollusca Arthropoda Annelida Protostomes (from the Greek: first the mouth) are a superphylum of animals in the taxonomic group bilateria, and include animals such as arthropods, mollusks, and nematodes. ...

However, many skeptics emphasize the pitfalls and inconsistencies associated with the new data. Claus Nielsen, a professor of evolutionary invertebrate embryology at the Zoological Museum University of Copenhagen champions one of the most prominent alternative views based on morphological evidence. In his 2001 book Animal Evolution: Interrelationships of the Living Phyla, he maintains the traditional divisions of Protostomia and Deuterostomia. Buildings in the H. C. Ørsted Institute Niels Bohr Institute for Astronomy, Physics and Geophysics Institute for Mathematical Sciences August Krogh Institute The Faculty of Science (Det naturvidenskabelige fakultet in Danish) at the University of Copenhagen consists of both mathematical and natural sciences, and is divided into 11 institutes including... Groups Ecdysozoa Lophotrochozoa Platyzoa Protostomes (from the Greek: first the mouth) are a taxon of animals. ... Phyla Echinodermata Hemichordata Chordata Xenoturbellida Chaetognatha (uncertain) Vetulicolia † Deuterostomes (taxonomic term: Deuterostomia; from the Greek: second mouth) are a superphylum of animals. ...

Evolutionary origins

It has been suggested that one type of molecular clock and one approach to interpretation of the fossil record both place the evolutionary origins of eumetazoa in the Ediacaran.^[3] However, the earliest eumetazoans may not have left a clear impact on the fossil record and other interpretations of molecular clocks suggest the possibility of an earlier origin.^[4] The discoverers of Vernanimalcula describe it as the fossil of a bilateral triploblastic animal that appeared at the end of the Marinoan glaciation prior to the Ediacaran Period, implying an even earlier origin for eumetazoans.^[5] The molecular clock (based on the molecular clock hypothesis (MCH)) is a technique in genetics, which researchers use to date when two species diverged. ... The Ediacaran Period is the last geological period of the Neoproterozoic Era, just before the Cambrian. ... The oldest known examples of a bilaterian, bilateral animals. ... Bilateralism is a term referring to trade or political relations between two states. ... Triploblastic is a condition of the ovum in which there are three primary germinal layers: the ectoderm, mesoderm, and endoderm. ... The Cryogenian Period (from Greek cryos ice and genesis birth) is the second geologic period of the Neoproterozoic Era, followed by the Ediacaran Period. ... The Ediacaran Period is the last geological period of the Neoproterozoic Era, just before the Cambrian. ...

References

Wikispecies has information related to:

Eumetazoa

• Bilateria. Tree of Life web project, US National Science Foundation. 2002. 6 Jan 2006.
• Invertebrates and the Origin of Animal Diversity
• Evers, Christine A., Lisa Starr. Biology:Concepts and Applications. 6th ed. United States:Thomson, 2006. ISBN 0-534-46224-3.
• Metazoa: the Animals
• Nielsen, C. 2001. Animal Evolution: Interrelationships of the Living Phyla, 2nd edition, 563 pp. Oxford Univ. Press, Oxford. ISBN 0-19-850681-3
• Borchiellini, C. Manuel, M., Alivon, E., Boury-Esnault N., Vacelet, J., Le-Parco, Y. 2001. Journal of Evolutionary Biology 14 (1): 171-179.
• Peterson, Kevin J., McPeek, Mark A., & Evans, David A.D. 2005. Tempo & mode of early animal evolution: inferences from rocks, Hox, & molecular clocks. Paleobiology 31(2, Supplement): 36-55.