Maxillopoda Dahl, 1956
Abrsiidae Karanovic, 2008
Anchimolgidae Humes & Boxshall, 1996
Anomoclausiidae Gotto, 1964
Anthessiidae Humes, 1986
Bomolochidae Sumpf, 1871
Bradophilidae Marchenkov, 2002
Charlesia Oliveira, 1945
Chitonophilidae Avdeev & Sirenko, 1991
Chondracanthidae Milne Edwards, 1840
Clausidiidae Embleton, 1901
Clausiidae Giesbrecht, 1895
Corallovexiidae Stock, 1975
Corycaeidae Dana, 1852
Echiurophilidae Delamare-Deboutteville & Nunes-Ruivo, 1955
Endocheres Bocquet & Stock, 1956
Entobiidae Ho, 1984
Erebonasteridae Humes, 1987
Ergasilidae von Nordmann, 1832
Gastrodelphyidae List, 1889
Herpyllobiidae Hansen, 1892
Intramolgidae Marchenkov & Boxshall, 1995
Kelleriidae Humes & Boxshall, 1996
Lamippidae Joliet, 1882
Lernaeosoleidae Yamaguti, 1963
Lichomolgidae Kossmann, 1877
Lubbockiidae Huys & Böttger-Schnack, 1997
Macrochironidae Humes & Boxshall, 1996
Makrostrotidae Huys, Fatih, Ohtsuka & Llewellyn-Hughes, 2011
Mesoglicolidae de Zulueta, 1911
Micrallectidae Huys, 2001
Myicolidae Yamaguti, 1936
Mytilicolidae Bocquet & Stock, 1957
Nereicolidae Claus, 1875
Nucellicolidae Lamb, Boxshall, Mill & Grahame, 1996
Octophiophora Stock, 1988
Octopicolidae Humes & Boxshall, 1996
Oncaeidae Giesbrecht, 1893
Paralubbockiidae Boxshall & Huys, 1989
Pharodidae Illg, 1948
Philichthyidae Vogt, 1877
Phyllodicolidae Delamare-Deboutteville & Laubier, 1961
Pionodesmotidae Bonnier, 1898
Polyankylidae Ho & Kim, 1997
Polyankyliidae Ho & Kim I.H., 1997
Pseudanthessiidae Humes & Stock, 1972
Rhynchomolgidae Humes & Stock, 1972
Sabelliphilidae Gurney, 1927
Saccopsidae Lützen, 1964
Sapphirinidae Thorell, 1860
Serpulidicolidae Stock, 1979
Shiinoidae Cressey, 1975
Spiophanicolidae Ho, 1984
Splanchnotrophidae Norman & Scott, 1906
Synaptiphilidae Bocquet, 1953
Taeniacanthidae Wilson, 1911
Tegobomolochidae Avdeev, 1978
Telsidae Ho, 1967
Thamnomolgidae Humes & Boxshall, 1996
Tuccidae Vervoort, 1962
Urocopiidae Humes & Stock, 1972
Vahiniidae Humes, 1967
Ventriculinidae Leigh-Sharpe, 1934
Xenocoelomatidae Bresciani & Lützen, 1966