Topic summary
Deuterostomia
Extracted from the Wikipedia article Deuterostome.
Deuterostomia's sister clade is Protostomia, animals that develop mouth first and whose digestive tract development is more varied. Protostomia includes the ecdysozoans and spiralians. Together with the Xenacoelomorpha, these constitute the large cladeBilateria, i.e. animals with bilateral symmetry and three germ layers.