Aaronia A. H. Verrill, 1950 accepted as Muricanthus Swainson, 1840 accepted as Hexaplex Perry, 1810 (verified source for family)
Aberrodomus Gordon, 1988 (verified source for family)
Abrina Habe, 1952 accepted as Abra Lamarck, 1818 (verified source for family)
Abyssijaera Menzies, 1962 accepted as Katianira Hansen, 1916 (verified source for family)
Abyssocypris van den Bold, 1974 (verified source for family)
Acanthais Vermeij & Kool, 1994 (verified source for family)
Acantharchaster Verrill, 1894 accepted as Luidiaster Studer, 1884 accepted as Cheiraster Studer, 1883 (verified source for family)
Acanthinucella Cooke, 1918 (verified source for family)
Acanthodiscus Volkmer-Ribeiro, 1996 accepted as Racekiela Bass & Volkmer-Ribeiro, 1998 (verified source for family)
Acanthotrema Oshmarin & Parakhin, 1960 accepted as Pandiontrema Oshmarin, 1963 (verified source for family)
Acherusia Lucas, 1849 accepted as Rocinela Leach, 1818 (verified source for family)
Acicula Hartmann, 1821 (verified source for family)
Acicularia Langerhans, 1877 (verified source for family)
Aclymene Buzhinskaja, 1995 (verified source for family)
Acupurpura Jousseaume, 1880 accepted as Murex Linnaeus, 1758 (verified source for family)
Adelasterias Verrill, 1914 (verified source for family)
Adelieledone Allcock, Hochberg, Rodhouse & Thorpe, 2003 (verified source for family)
Aegacylla Dana, 1852 accepted as Aega Leach, 1815 (verified source for family)
Aegiochus Bovallius, 1885 (verified source for family)
Aegoniscus Barnard, 1925 (verified source for family)
Africanella Vermeij & Houart, 1999 (verified source for family)
Afroturbonilla Peñas, Rolán & Schander, 1999 (verified source for family)
Agaphelus Cope, 1868 accepted as Balaenoptera Lacépède, 1804 (verified source for family)
Agenor Risso, 1827 accepted as Argulus O.F. Müller, 1785 (verified source for family)
Agulanthura Kensley, 1975 accepted as Quantanthura Menzies & George, 1972 (verified source for family)
Ailsaria Fell, 1962 accepted as Amphioplus Verrill, 1899 (verified source for family)
Aleutiaster A.H. Clark, 1939 (verified source for family)
Alexandraster Ludwig, 1905 accepted as Poraniopsis Perrier, 1891 (verified source for family)
Aliama Gray, 1864 accepted as Ziphius Cuvier, 1823 (verified source for family)
Alipurpura Bayle in P. Fischer, 1884 accepted as Pterochelus Jousseaume, 1880 (verified source for family)
Alterammina Brönnimann & Whittaker, 1988 (verified source for family)
Alveolaria Johnston, 1865 accepted as Sabellaria Lamarck, 1818 (verified source for family)
Amacrodorum Kudenov, 1987 accepted as Euritmia Sarda-Borroy, 1987 (verified source for family)
Amembranaster Golotsvan, 1998 (verified source for family)
Amphibranchus Kinberg, 1867 accepted as Hermodice Kinberg, 1857 (verified source for family)
Amphilocus Ortiz & Lalana, 2002 accepted as Amphilochus Spence Bate, 1862 (basis of record)
Amphioctopus P. Fischer, 1882 (verified source for family)
Amphiserpula Uchida, 1978 accepted as Spiraserpula Regenhardt, 1961 (verified source for family)
Amphitritoides Costa, 1862 accepted as Eupolymnia Verrill, 1900 (verified source for family)
Amytis Savigny, 1822 accepted as Proceraea Ehlers, 1864 (verified source for family)
Anaphia Say, 1821 accepted as Anoplodactylus Wilson, 1878 (verified source for family)
Anarthron Kornicker, 1975 (verified source for family)
Andreina Brian, 1939 (verified source for family)
Anisoceras Grube, 1856 accepted as Dorvillea Parfitt, 1866 (verified source for family)
Anisomelus Templeton, 1835 (verified source for family)
Anisopechys Bird, 2004 (verified source for family)
Anomalosymtes Hendrycks & Bousfield, 2004 (verified source for family)
Anomorhynchus Miers, 1881 accepted as Colossendeis Jarzynsky, 1870 (verified source for family)
Anophthalmus Alikuhni, 1949 accepted as Alikuhnia Hartman, 1959 (verified source for family)
Anops Oken, 1815 accepted as Haemobaphes Steenstrup & Lütken, 1861 (verified source for family)
Antalium Guettard, 1770 accepted as Serpula Linnaeus, 1758 (verified source for family)
Antarcticythere Neale, 1967 (verified source for family)
Antarctiloxoconcha Hartmann, 1986 (verified source for family)
Anthosticte Fisher, 1911 accepted as Tethyaster Sladen, 1889 (verified source for family)
Antillogorgia Bayer, 1951 (verified source for family)
Antimurex Cossmann, 1903 accepted as Crassilabrum Jousseaume, 1880 (verified source for family)
Antrisocopia Fosshagen in Fosshagen & Iliffe, 1985 (verified source for family)
Aonopsis Wagner, 1885 (verified source for family)
Aphanibranchion Oka, 1906 accepted as Diazona Savigny, 1816 (verified source for family)
Aphanocomaster Messing, 1995 (verified source for family)
Aphelasterias Fisher, 1923 (verified source for family)
Aphotocentor Huys, 1991 (verified source for family)
Apiocardia Olsson, 1961 (verified source for family)
Apneumea Quatrefages, 1866 accepted as Polycirrus Grube, 1850 (verified source for family)
Apomatopsis de Saint-Joseph, 1894 accepted as Apomatus Philippi, 1844 (verified source for family)
Aponobranchus Gravier, 1905 accepted as Terebellides Sars, 1835 (verified source for family)
Apterodon Fisher, 1940 accepted as Pteraster Müller & Troschel, 1842 (verified source for family)
Araeosternus Man, 1881 accepted as Palinurellus von Martens, 1878 (verified source for family)
Archidiaptomus Madhupratap & Haridas, 1978 (verified source for family)
Archioncaea Böttger-Schnack & Huys, 1997 (verified source for family)
Archizausodes Bouck, Thistle & Huys, 1999 (verified source for family)
Arcticocamptus Chappuis, 1928 (verified source for family)
Arctokonstantinus Markhaseva & Kosobokova, 2001 (verified source for family)
Arcturocheres Hansen, 1916 (verified source for family)
Arcturosaccus Rybakov & Høeg, 1992 (verified source for family)
Arenocalanus Wilson, 1935 accepted as Platycopia G.O. Sars, 1911 (verified source for family)
Argentinochondria Etchegoin, Timi & Sardella, 2003 (verified source for family)
Argoderma Poli, 1795 accepted as Pecten O. F. Müller, 1776 (verified source for family)
Arhynchonemertes Riser, 1988 (verified source for family)
Ariapithes Kinberg, 1867 (verified source for family)
Aricideopsis Johnson, 1901 accepted as Laonice Malmgren, 1867 (verified source for family)
Aricinella Quatrefages, 1844 (verified source for family)
Aristochiton Thiele, 1909 accepted as Notoplax H. Adams, 1862 (verified source for family)
Aristostomias Zugmayer, 1940 (verified source for family)
Articulatia Nogueira, Hutchings & Amaral, 2003 (verified source for family)
Aryandes Kinberg, 1867 (verified source for family)
Ashinkailepas Yamaguchi, Newman & Hashimoto, 2004 (verified source for family)
Aspidonotus G.O. Sars, 1897 accepted as Aspidarachna G.O. Sars, 1897 (verified source for family)
Aspinothorax Moura & Martínez Arbizu, 2004 (verified source for family)
Astacilloechus Hansen, 1916 accepted as Arcturocheres Hansen, 1916 (verified source for family)
Asteroderma Perrier, 1888 accepted as Anasterias Perrier, 1875 (verified source for family)
Asteropontius Thompson & Scott in Herdman, 1903 (verified source for family)
Astioglossimetra Bilqees, Khatoon & Khan, 2002 (verified source for family)
Astrosarkus Mah, 2003 (verified source for family)
Astrothauma Fisher, 1913 (verified source for family)
Asymmetrorbione Boyko, 2003 (verified source for family)
Atelorias Fisher, 1911 (verified source for family)
Atlanticythere Benson, 1977 † (verified source for family)
Austrochlamys Jonkers, 2003 (verified source for family)
Austrocythere Hartmann, 1989 (verified source for family)