group of protostome animals

The Ecdysozoa (including Cycloneuralia) are a group of protostome animal phyla. This is a taxon above the level of phylum. It includes the Arthropoda (insects and crustaceans), Nematoda, and several smaller phyla.[1]

Temporal range: Lower Cambrian – Recent
Centipede (Panarthropoda)
Scientific classification

Aguinaldo et al., 1997
Phyla, classes, and clades

They were first defined in 1997, based mainly on phylogenetic trees taken from 18S ribosomal RNA genes.[2] A large study in 2008 strongly supported the Ecdysozoa as a clade, that is, a group consisting of a common ancestor and all its descendants.[3]

The group is also supported by morphological characters, and includes all animals that shed their exoskeleton (see ecdysis).


  1. Telford M.J. et al 2008. The evolution of the Ecdysozoa. Philos. Trans. R. Soc. Lond., B. 363 (1496): 1529–37. doi:10.1098/rstb.2007.2243. PMC 2614232. PMID 18192181 Missing or empty |title= (help)
  2. Aguinaldo A.M.A. et al 1997. Evidence for a clade of nematodes, arthropods and other moulting animals. Nature. 387 (6632): 489–493. doi:10.1038/387489a0. PMID 9168109. Missing or empty |title= (help)
  3. Dunn C.W. et al 2008. Broad phylogenomic sampling improves resolution of the animal tree of life (2008). Nature. 452 (7188): 745–749. doi:10.1038/nature06614. PMID 18322464. Missing or empty |title= (help) [1]