Note

Guide to Names Used in the Higher Classification of Animals

The phylogenetic relationships among the major groups of animals are currently the subject of a lively debate, and most scientists would agree that the elucidation of metazoan relationships is still very much a work in progress. A definitive, stable, and natural classification of animals at higher taxonomic levels is therefore at present premature. These limitations notwithstanding, suggestions for new or revised naming conventions continue to be published along with preliminary hypotheses of animal relationships. As a result, a host of different higher level names is tossed about in the zoological literature, and the usage of any given name may vary from author to author. This situation can create considerable confusion among fledgling students of zoology.

In order to make the reading of zoological literature a little easier, we provide here a list of commonly encountered names of higher level groups of animals along with information on how these names have been defined in some prominent zoological publications (full references are provided below). A name that appears in the literature is given in blue; the publication that used that name is referenced underneath the name in green. The groups listed following each reference are those groups (using group names found in Tree of Life pages) that are specified in the publication as belonging within the name being defined.


Acanthognatha
Cavalier-Smith 1998: Gastrotricha, Gnathostomulida, Rotifera
Acoelomata
Hyman 1951a: Nemertea, Platyhelminthes
Acrosomata
Ax 1996: Ctenophora, Bilateria
Ambulacralia
Zrzavy & al. 1998: Echinodermata, Hemichordata
Ambulacraria
Peterson & Eernisse 2001: Echinodermata, Hemichordata
Animalia
Zrzavy & al. 1998: Choanoflagellates, Metazoa
Nielsen 2001: syn. Metazoa: Bilateria, Cnidaria, Ctenophora, Placozoa, Porifera
Arthropoda
Ax 2000: Arthropoda, Onychophora
Articulata
Ghiselin 1988: Articulata s. l.: Annelida, Arthropoda, Brachiopoda, Mollusca, Sipuncula
Ax 2000: Annelida, Arthropoda, Onychophora
Nielsen 2001: Annelida, Arthropoda, Mollusca, Onychophora, Tardigrada
Aschelminthes
Hyman 1951b: Gastrotricha, Kinorhyncha, Nematoda, Nematomorpha, Priapulida, Rotifera
Nielsen 1995: Chaetognatha, Gastrotricha, Kinorhyncha, Loricifera, Nematoda, Nematomorpha, Priapulida, Rotifera
Ehlers & al. 1996: syn. Nemathelminthes: Gastrotricha, Kinorhyncha, Loricifera, Nematoda, Nematomorpha, Priapulida
Kristensen & Funch 2000: syn. Pseudocoelomata: Gastrotricha, Gnathostomulida, Kinorhyncha, Loricifera, Micrognathozoa, Nematoda, Nematomorpha, Priapulida, Rotifera

Bilateria
Nielsen 1995: Annelida, Arthropoda, Brachiopoda, Bryozoa, Chaetognatha, Ctenophora, Deuterostomia, Entoprocta, Gastrotricha, Gnathostomulida, Kinorhyncha, Loricifera, Mollusca, Nematoda, Nematomorpha, Nemertea, Onychophora, Phoronida, Platyhelminthes, Priapulida, Rotifera, Sipuncula, Tardigrada
Zrzavy & al. 1998: syn. Triploblastica: Annelida, Arthropoda, Brachiopoda, Bryozoa, Chaetognatha, Cycliophora, Deuterostomia, Entoprocta, Gastrotricha, Gnathostomulida, Kinorhyncha, Loricifera, Mesozoa, Mollusca, Nematoda, Nematomorpha, Nemertea, Onychophora, Phoronida, Platyhelminthes, Priapulida, Rotifera, Sipuncula, Tardigrada
Nielsen 2001: Annelida, Arthropoda, Brachiopoda, Bryozoa, Chaetognatha, Deuterostomia, Entoprocta, Gastrotricha, Gnathostomulida, Kinorhyncha, Loricifera, Micrognathozoa, Mollusca, Nematoda, Nematomorpha, Nemertea, Onychophora, Phoronida, Platyhelminthes, Priapulida, Rotifera, Sipuncula, Tardigrada
Brachiozoa
Cavalier-Smith 1998: Brachiopoda, Phoronida

Cephalorhyncha
Zrzavy & al. 1998, Nielsen 2001: Kinorhyncha, Loricifera, Priapulida
Chaetifera
Zrzavy & al. 1998, Nielsen 2001: Annelida, Echiura, Pogonophora
Coelenterata
Cavalier-Smith 1998: Cnidaria, Ctenophora
Cryptotreta
Nielsen 2001: Chordata, Enteropneusta
Cycloneuralia
Ehlers & al. 1996, Peterson & Eernisse 2001: Kinorhyncha, Loricifera, Nematoda, Nematomorpha, Priapulida
Nielsen 2001: Gastrotricha, Kinorhyncha, Loricifera, Nematoda, Nematomorpha, Priapulida

Deuterostomia
Hyman 1959: syn. Enterocoela: Chaetognatha (but inclusion considered doubtful), Chordata, Echinodermata, Hemichordata, Pogonophora
Zrzavy & al. 1998, Peterson & Eernisse 2001: Chordata, Echinodermata, Hemichordata
Nielsen 2001: Brachiopoda, Chordata, Echinodermata, Enteropneusta, Phoronida, Pterobranchia

Ecdysozoa
Aguinaldo & al. 1997: Last common ancestor of Arthropoda, Kinorhyncha, Nematoda, Nematomorpha, Onychophora, Priapulida, Tardigrada and all the descendants of that common ancestor.
Cavalier-Smith 1998, Garey & Schmidt-Rhaesa 1998: Arthropoda, Kinorhyncha, Loricifera, Nematoda, Nematomorpha, Onychophora, Priapulida, Tardigrada
Zrzavy & al. 1998, Peterson & Eernisse 2001: Arthropoda, Chaetognatha, Kinorhyncha, Loricifera, Nematoda, Nematomorpha, Onychophora, Priapulida, Tardigrada
Ectoprocta
Hyman 1959, Nielsen 2001: Bryozoa
Enterocoela
Hyman 1959: syn. Deuterostomia: Chaetognatha (inclusion considered doubtful), Chordata, Echinodermata, Hemichordata, Pogonophora
Epitheliozoa
Ax 1996, Nielsen 2001, Peterson & Eernisse 2001: Bilateria, Cnidaria, Ctenophora, Placozoa
Euarticulata
Nielsen 2001: Annelida, Arthropoda, Onychophora, Tardigrada
Eucoelomata
Hyman 1940: Annelida, Arthropoda, Brachiopoda, Bryozoa, Chaetognatha, Chordata, Echinodermata, Hemichordata, Mollusca, Phoronida, Priapulida, Sipuncula
Zrzavy & al. 1998: Annelida, Brachiopoda, Bryozoa, Chordata, Cycliophora, Echinodermata, Entoprocta, Hemichordata, Mollusca, Nemertea, Phoronida, Sipuncula
Eumetazoa
Hyman 1940, Ax 1996, Nielsen 2001, Peterson & Eernisse 2001: Bilateria, Cnidaria, Ctenophora
Euspiralia
Ax 1996: Annelida, Arthropoda, Entoprocta, Mollusca, Nemertea, Onychophora, Sipuncula
Eutriploblastica
Zrzavy & al. 1998: Annelida, Arthropoda, Brachiopoda, Bryozoa, Chaetognatha, Cycliophora, Deuterostomia, Entoprocta, Gastrotricha, Gnathostomulida, Kinorhyncha, Loricifera, Mollusca, Nematoda, Nematomorpha, Nemertea, Onychophora, Phoronida, Platyhelminthes (excluding Acoela & Nemertodermatida), Priapulida, Rotifera, Sipuncula, Tardigrada
Eutrochozoa
Ghiselin 1988: Annelida, Mollusca, Brachiopoda, Sipuncula
Zrzavy & al. 1998, Peterson & Eernisse 2001: Annelida, Mollusca, Nemertea, Sipuncula

Gnathifera
Sørensen & al. 2000: Gnathostomulida, Micrognathozoa, Rotifera
Nielsen 2001: Chaetognatha, Gnathostomulida, Micrognathozoa, Rotifera

Introverta
Nielsen 2001: Kinorhyncha, Loricifera, Nematoda, Nematomorpha, Priapulida

Lobopoda
Cavalier-Smith 1998: Onychophora, Tardigrada
Lophophorata
Hyman 1959: Brachiopoda, Bryozoa, Phoronida
Peterson & Eernisse 2001: Brachiopoda, Phoronida
Lophotrochozoa
Halanych & al. 1995: Last common ancestor of Annelida, Brachiopoda, Bryozoa, Mollusca, Phoronida and all the descendants of that common ancestor.
Garey & Schmidt-Rhaesa 1998: Annelida, Brachiopoda, Bryozoa, Entoprocta, Mollusca, Phoronida, Sipuncula
Peterson & Eernisse 2001: Annelida, Brachiopoda, Bryozoa, Cycliophora, Entoprocta, Gnathostomulida, Mollusca, Nemertea, Platyhelminthes, Phoronida, Rotifera, Sipuncula
Lophozoa
Cavalier-Smith 1998: Annelida, Brachiopoda, Bryozoa, Cycliophora, Entoprocta, Mollusca, Nemertea, Phoronida, Sipuncula

Metazoa
Hyman 1940: Bilateria, Cnidaria, Ctenophora, Mesozoa, Porifera
Nielsen 2001: syn. Animalia: Bilateria, Cnidaria, Ctenophora, Placozoa, Porifera
Monokonta
Cavalier-Smith 1998: Gastrotricha, Gnathostomulida

Nemathelminthes
Ehlers & al. 1996: syn. Aschelminthes: Gastrotricha, Kinorhyncha, Loricifera, Nematoda, Nematomorpha, Priapulida
Cavalier-Smith 1998: Kinorhyncha, Loricifera, Nematoda, Nematomorpha, Priapulida
Nematoida
Cavalier-Smith 1998, Peterson & Eernisse 2001: Nematoda, Nematomorpha
Nematoidea
Ehlers & al. 1996: Nematoda, Nematomorpha
Nematozoa
Zrzavy & al. 1998: Nematoda, Nematomorpha
Nemertina
Cavalier-Smith 1998: Nemertea
Nemertini
Ax 1996, Nielsen 2001: Nemertea
Neorenalia
Nielsen 2001: Chordata, Echinodermata, Enteropneusta, Pterobranchia
Neotrichozoa
Zrzavy & al. 1998: Gastrotricha, Gnathostomulida
Neotrochozoa
Peterson & Eernisse 2001: Annelida, Mollusca, Sipuncula
Neotriploblastica
Zrzavy & al. 1998: Annelida, Arthropoda, Brachiopoda, Bryozoa, Chaetognatha, Chordata, Cycliophora, Echinodermata, Entoprocta, Gastrotricha, Gnathostomulida, Hemichordata, Kinorhyncha, Loricifera, Mollusca, Nematoda, Nematomorpha, Nemertea, Onychophora, Phoronida, Priapulida, Rotifera, Sipuncula, Tardigrada

Panarthropoda
Nielsen 2001, Peterson & Eernisse 2001: Arthropoda, Onychophora, Tardigrada
Paracoelomata
Zrzavy & al. 1998: Arthropoda, Chaetognatha, Gastrotricha, Gnathostomulida, Kinorhyncha, Loricifera, Nematoda, Nematomorpha, Onychophora, Priapulida, Rotifera, Tardigrada
Parazoa
Hyman 1940: syn. Porifera
Parenchymia
Nielsen 2001: Nemertea, Platyhelminthes
Phoronozoa
Zrzavy & al. 1998: Brachiopoda, Phoronida
Platyhelminthomorpha
Ax 1996: Gnathostomulida, Platyhelminthes
Platyzoa
Cavalier-Smith 1998: Gastrotricha, Gnathostomulida, Platyhelminthes, Rotifera
Peterson & Eernisse 2001: Cycliophora, Gnathostomulida, Platyhelminthes, Rotifera
Polyzoa
Cavalier-Smith 1998: Bryozoa, Entoprocta
Priapozoa
Cavalier-Smith 1998: Loricifera, Priapulida
Proctozoa
Ghiselin 1988: Bilateria excluding Platyhelminthes
Protostomia
Hyman 1940: Annelida, Arthropoda, Brachiopoda, Bryozoa, Entoprocta, Gastrotricha, Kinorhyncha, Mollusca, Nematoda, Nematomorpha, Nemertea, Phoronida, Platyhelminthes, Priapulida, Rotifera, Sipuncula
Nielsen 2001: Annelida, Arthropoda, Bryozoa, Chaetognatha, Entoprocta, Gastrotricha, Gnathostimulida, Kinorhyncha, Loricifera, Micrognathozoa, Mollusca, Nematoda, Nematomorpha, Nemertea, Onychophora, Platyhelminthes, Priapulida, Rotifera, Sipuncula, Tardigrada
Peterson & Eernisse 2001: Annelida, Arthropoda, Brachiopoda, Bryozoa, Chaetognatha, Cycliophora, Entoprocta, Gastrotricha, Gnathostomulida, Kinorhyncha, Loricifera, Mollusca, Nematoda, Nematomorpha, Nemertea, Onychophora, Phoronida, Platyhelminthes, Priapulida, Rotifera, Sipuncula, Tardigrada
Pseudocoelomata
Hyman 1951b: Entoprocta, Gastrotricha, Kinorhyncha, Nematoda, Nematomorpha, Priapulida, Rotifera
Lorenzen 1985: Gastrotricha, Kinorhyncha, Loricifera, Nematoda, Nematomorpha, Priapulida, Rotifera
Kristensen & Funch 2000: syn. Aschelminthes: Gastrotricha, Gnathostomulida, Kinorhyncha, Loricifera, Micrognathozoa, Nematoda, Nematomorpha, Priapulida, Rotifera

Radialia
Ax 1996: Brachiopoda, Bryozoa, Deuterostomia, Phoronida
Radiata
Hyman 1940: Cnidaria, Ctenophora
Cavalier-Smith 1998: Cnidaria, Ctenophora, Placozoa, Porifera
Rhynchocoela
Hyman 1951a: Nemertea

Scalidophora
Ehlers & al. 1996, Peterson & Eernisse 2001: Kinorhyncha, Loricifera, Priapulida
Scalidorhyncha
Cavalier-Smith 1998: Kinorhyncha, Loricifera, Priapulida
Schizocoela
Hyman 1940: Annelida, Arthropoda, Brachiopoda, Bryozoa, Mollusca, Phoronida, Priapulida, Sipuncula
Schizocoelia
Nielsen 2001: syn. Teloblastica: Annelida, Arthropoda, Mollusca, Onychophora, Sipuncula, Tardigrada
Spiralia
Nielsen 1995: Annelida, Arthropoda, Bryozoa, Entoprocta, Gnathostomulida, Mollusca, Nemertea, Onychophora, Platyhelminthes, Sipuncula, Tardigrada
Ax 1996: Annelida, Arthropoda, Entoprocta, Gnathostomulida, Mollusca, Nemertea, Onychophora, Platyhelminthes, Sipuncula
Garey & Schmidt-Rhaesa 1998: Annelida, Brachiopoda, Bryozoa, Entoprocta, Gastrotricha, Gnathostomulida, Mollusca, Phoronida, Platyhelminthes, Rotifera, Sipuncula
Nielsen 2001: Annelida, Arthropoda, Bryozoa, Chaetognatha, Entoprocta, Gnathostomulida, Micrognathozoa, Mollusca, Nemertea, Onychophora, Platyhelminthes, Rotifera, Sipuncula, Tardigrada
Peterson & Eernisse 2001: Annelida, Bryozoa, Cycliophora, Entoprocta, Gnathostomulida, Mollusca, Nemertea, Platyhelminthes, Rotifera, Sipuncula
Syndermata
Zrzavy & al. 1998: Rotifera including Acanthocephala

Teloblastica
Nielsen 2001: syn. Schizocoelia: Annelida, Arthropoda, Mollusca, Onychophora, Sipuncula, Tardigrada
Tentaculata
Ax 1996: group not considered monophyletic: Brachiopoda, Bryozoa, Phoronida
Triploblastica
Zrzavy & al. 1998: syn. Bilateria: Annelida, Arthropoda, Brachiopoda, Bryozoa, Chaetognatha, Cycliophora, Deuterostomia, Entoprocta, Gastrotricha, Gnathostomulida, Kinorhyncha, Loricifera, Mesozoa, Mollusca, Nematoda, Nematomorpha, Nemertea, Onychophora, Phoronida, Platyhelminthes, Priapulida, Rotifera, Sipuncula, Tardigrada
Nielsen 2001: Bilateria, Ctenophora
Trochozoa
Zrzavy & al. 1998: Annelida, Cycliophora, Entoprocta, Mollusca, Nemertea, Sipuncula
Ax 2000: Annelida, Arthropoda, Entoprocta, Mollusca, Sipuncula
Peterson & Eernisse 2001: Annelida, Entoprocta, Mollusca, Nemertea, Sipuncula

Vermizoa
Cavalier-Smith 1998: Annelida, Nemertea

References

Aguinaldo, A. M. A., J. M. Turbeville, L. S. Linford, M. C. Rivera, J. R. Garey, R. A. Raff, and J. A. Lake. 1997. Evidence for a clade of nematodes, arthropods and other moulting animals. Nature 387:489-493.

Ax, P. 1996. Multicellular Animals. A New Approach to the Phylogenetic Order in Nature. Volume I. Springer Verlag, Berlin, Heidelberg, New York.

Ax, P. 2000. Multicellular Animals. The Phylogenetic System of the Metazoa. Volume II. Springer Verlag, Berlin, Heidelberg, New York.

Cavalier-Smith, T. 1998. A revised six-kingdom system of life. Biological Reviews 73:203-266.

Ehlers, U., W. Ahlrichs, C. Lemburg and A. Schmidt-Rhaesa. 1996. Phylogenetic systematization of the Nemathelminthes (Aschelminthes). Verhandlungen der Deutschen Zoologischen Gesellschaft 89:8.

Garey, J. R. and A. Schmidt-Rhaesa. 1998. The essential role of "minor" phyla in molecular studies of animal evolution. American Zoologist 38:907-917.

Ghiselin, M. T. 1988. The origin of molluscs in the light of molecular evidence. Oxford Surveys in Evolutionary Biology 5:66-95.

Halanych, K. M., J. D. Bacheller, A. M. A. Aguinaldo, S. M. Liva, D. M. Hillis and J. A. Lake. 1995. Evidence from 18S ribosomal DNA that the lophophorates are protostome animals. Science 267:1641-1643.

Hyman, L. H. 1940. The Invertebrates. Volume 1, Protozoa through Ctenophora. McGraw-Hill Book Company, Inc., New York and London.

Hyman, L. H. 1951a. The Invertebrates. Volume 2, Platyhelminthes and Rhynchocoela. McGraw-Hill Book Company, Inc., New York and London.

Hyman, L. H. 1951b. The Invertebrates. Volume 3, Acanthocephala, Aschelminthes, and Entoprocta. McGraw-Hill Book Company, Inc., New York and London.

Hyman, L. H. 1959. The Invertebrates. Volume 5, Smaller coelomate groups. McGraw-Hill Book Company, Inc., New York and London.

Kristensen, R. M. and P. Funch. 2000. Micrognathozoa: A new class with complicated jaws like those of Rotifera and Gnathostomulida. Journal of Morphology 246:1-49.

Lorenzen, S. 1985. Phylogenetic aspects of pseudocoelomate evolution. Pages 210-223 in The Origins and Relationships of Lower Invertebrates. S. C. Morris, J. D. George, R. Gibson and H. M. Platt, eds. Oxford University Press, Oxford.

Nielsen, C. 1995. Animal Evolution: Interrelationships of the Living Phyla. First Edition. Oxford University Press, Oxford.

Nielsen, C. 2001. Animal Evolution: Interrelationships of the Living Phyla. Second Edition. Oxford University Press, Oxford.

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.

Sørensen, M. V., P. Funch, E. Willerslev, A. J. Hansen, and J. Olesen. 2000. On the phylogeny of the Metazoa in light of Cycliophora and Micrognathozoa. Zoologischer Anzeiger 239:297-318.

Zrzavy, J., S. Mihulka, P. Kepka, A. Bezdek, and D. Tietz. 1998. Phylogeny of the Metazoa based on morphological and 18S ribosomal DNA evidence. Cladistics 14:249-285.

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