Ecdysozoa

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. 

They were first defined in 1997, based mainly on phylogenetic trees taken from 18S ribosomal RNA genes. 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. 

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

 References 

Category:Groups of phyla
Category:Animals
Category:Invertebrates