Hydrozoa Owen, 1843
Aequoreidae Eschscholtz, 1829
Aglaopheniidae Marktanner-Turneretscher, 1890
Barcinididae Gili, Bouillon, Pagès, Palanques & Puig, 1999
Blackfordiidae Bouillon, 1984
Bonneviellidae Broch, 1909
Campanulariidae Johnston, 1836
Campanulinidae Hinks, 1868
Cirrholoveniidae Bouillon, 1984
Clathrozoidae Stechow, 1921
Dipleurosomatidae Russell, 1953
Eirenidae Haeckel, 1879
Eucheilotidae
Haleciidae Hincks, 1868
Halopterididae Millard, 1962
Hebellidae Fraser, 1912
Kirchenpaueriidae Stechow, 1921
Lafoeidae Hincks, 1868
Laodiceidae Agassiz, 1862
Lineolariidae Allman, 1864
Lovenellidae Russell, 1953
Malagazziidae Bouillon, 1984
Melicertidae Agassiz, 1862
Mitrocomidae Haeckel, 1879
Octocannoididae Bouillon, Boero & Seghers, 1991
Orchistomidae Bouillon, 1984
Phialellidae Russell, 1953
Phialuciidae Kramp, 1955
Plumulariidae Agassiz, 1862
Sertulariidae Lamouroux, 1812
Sugiuridae Bouillon, 1984
Syntheciidae Marktanner-Turneretscher, 1890
Teclaiidae Bouillon, Pagès, Gili, Palanques, Puig & Heussner, 2000
Thyroscyphidae Stechow, 1920
Tiarannidae Russell, 1940
Tiaropsidae Boero, Bouillon & Danovaro, 1987