Exemples: all arthropods (insects, chelicerata, crustaceans, and myriapods), and nematoda.
It’s a philogenetic group composed by animals that have a three-layed-cuticle. This cuticle can be shifted as the animal grows in a processes called ecdysis.
References:
Telford MJ, Bourlat SJ, Economou A, Papillon D, Rota-Stabelli O (April 2008). “The evolution of the Ecdysozoa”. Philos. Trans. R. Soc. Lond., B, Biol. Sci. 363 (1496): 1529–37. doi:10.1098/rstb.2007.2243. PMC 2614232. PMID 18192181.
Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. pp. 877–880. ISBN 0-03-056747-5.
