The evolution of the Ecdysozoa

Philos Trans R Soc Lond B Biol Sci. 2008 Apr 27;363(1496):1529-37. doi: 10.1098/rstb.2007.2243.


Ecdysozoa is a clade composed of eight phyla: the arthropods, tardigrades and onychophorans that share segmentation and appendages and the nematodes, nematomorphs, priapulids, kinorhynchs and loriciferans, which are worms with an anterior proboscis or introvert. Ecdysozoa contains the vast majority of animal species and there is a great diversity of body plans among both living and fossil members. The monophyly of the clade has been called into question by some workers based on analyses of whole genome datasets. We review the evidence that now conclusively supports the unique origin of these phyla. Relationships within Ecdysozoa are also controversial and we discuss the molecular and morphological evidence for a number of monophyletic groups within this superphylum.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Biological Evolution*
  • Body Patterning
  • Invertebrates / classification*
  • Invertebrates / genetics*
  • Invertebrates / growth & development
  • Models, Biological
  • Phylogeny