| Molecular studies support the monophyly of all these taxa as Ecdysozoa, so the term Spiralia is sometimes used as a synonym for the non-molting protostomes, Lophotrochozoa. |
| In the complementary category of the protostomes, which includes annelids and arthropods, the blastopore develops into the mouth. |
| Chaetognaths were considered to be deuterostomes until quite recently, when they were relocated to the protostomes. |
| Arthropods are bilaterally symmetrical protostomes with strongly segmented bodies. |
| In the complementary category, the protostomes, which includes annelids and arthropods, the blastopore develops into the mouth. |
