Protostomia is the clade of animals once thought to be characterized by the creature's blastopore becoming its mouth during embryonic development. This nature has since been discovered to be extremely

Ecdysozoa is a group of protostome animals, including Arthropoda, Nematoda, and several smaller phyla. The grouping of these animal phyla into a single clade was first proposed by Eernisse et al. base