protostomes see [unranked] Protostomia Grobben, 1908
   Spiralia Schleip, 1929 - spiralians see Superphylum Spiralia Schleip, 1929
     Gnathifera Ahlrichs, 1995
       1.1.1 [Phylum] Rotifera Cuvier, 1798 - rotifers see Phylum Syndermata Ahlrichs, 1995
       1.1.2 [Phylum] Micrognathozoa Kristensen & Funch, 2000
       1.2 [Phylum] Gnathostomulida Ax, 1956 - gnathostomulids
       2 [Phylum] Chaetognatha Leuckart, 1854 - chaetognaths