Taxonomy of invertebrates (Brusca & Brusca, 2003)

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The taxonomy of invertebrates as proposed by Richard C. Brusca and Gary J. Brusca in 2003 is a system of classification with emphasis on the invertebrates, in other words, a way to classify animals, primarily those which have no backbone.[1]


Eukaryotes (Eukaryota, or Eukarya)[edit]

Kingdom Animalia (Metazoa)[edit]


Phylum Porifera[edit]


Phylum Placozoa[edit]
Phylum Monoblastozoa[edit]
Phylum Rhombozoa[edit]
Phylum Orthonectida[edit]


Phylum Cnidaria[edit]
Phylum Ctenophora[edit]

The authors divide the bilaterians in three informal groups:

  • acoelomates (phyla Platyhelminthes, Gastrotricha, Entoprocta, Gnathostomulida, Cycliophora)
  • blastocoelomate (or pseducoelomate, phyla Rotifera, Kinorhyncha, Nematoda, Nematomorpha, Acanthocephala, Loricifera)
  • coelomates (or eucoelomates, phyla Nemertea, Priapula, Annelida, Sipuncula, Echiura, Onychophora, Tardigrada, Arthropoda, Mollusca, Phoronida, Ectoprocta, Brachiopoda, Echinodermata, Chaetognatha, Hemichordata, Chordata).

Several groups traditionally viewed as having a blastocoelomate condition are viewed here as acoelomates (e.g., Gastrotricha, Entoprocta, Gnathostomulida).

Some of the coelomates groups (e.g., Arthropoda, Mollusca) have greatly reduced celomic spaces; often the main body cavity is a bloodfilled space called a hemocoel, and is associated with an open circulatory system.

The Brachiopoda, Ectoprocta and Phoronida are viewed as lophophorates.

In a phylogeny,[2] the bilaterians are divided in:

Phylum Platyhelminthes[edit]
Phylum Nemertea[edit]
Phylum Rotifera[edit]
Phylum Gastrotricha[edit]
Phylum Kinorhyncha[edit]
Phylum Nematoda (= Nemata)[edit]
Phylum Nematomorpha[edit]
Phylum Priapula[edit]
Phylum Acanthocephala[edit]
Phylum Entoprocta (= Kamptozoa)[edit]
Phylum Gnathostomulida[edit]
Phylum Loricifera[edit]
Phylum Cycliophora[edit]
Phylum Annelida[edit]
  • Class Polychaeta, with 25 orders and 87 families (not all are listed)
  • Order Haplotaxida, with 25 families (not all are listed)
Phylum Sipuncula[edit]
Phylum Echiura[edit]
Phylum Onychophora[edit]
Phylum Tardigrada[edit]
Phylum Arthropoda[edit]
Phylum Mollusca[edit]
Phylum Phoronida[edit]
Phylum Ectoprocta (= Bryozoa)[edit]
Phylum Brachiopoda[edit]
Phylum Echinodermata[edit]
Phylum Chaetognatha[edit]
Phylum Hemichordata[edit]
Phylum Chordata[edit]


  1. ^ Richard C. Brusca & Gary J. Brusca (2003). Invertebrates (2nd ed.). Sunderland, Massachusetts: Sinauer Associates. ISBN 978-0-87893-097-5.
  2. ^ Richard C. Brusca & Gary J. Brusca (2003), p. 875.