Abalistes Jordan & Seale, 1906 (additional source)
Abatus Troschel, 1851 (additional source)
Abditodentrix Patterson, 1985 (additional source)
Aberomysis Bacescu & Iliffe, 1986 (additional source)
Ablabys Kaup, 1873 (basis of record)
Ablepharus Fitzinger, 1823 (basis of record)
Abothrium Van Beneden, 1870 (basis of record)
Abudefduf Forsskål, 1775 (additional source)
Abyssascidia Herdman, 1880 (additional source)
Abyssaster Madsen, 1961 (additional source)
Abyssoclymene Hartman, 1967 (additional source)
Acaenomolgus Humes & Stock, 1972 (additional source)
Acanella Gray, 1870 (additional source)
Acanthanectes Holleman & Buxton, 1993 (basis of record)
Acanthaster Gervais, 1841 (additional source)
Acanthastrea Milne Edwards & Haime, 1848 (additional source)
Acanthephyra A. Milne-Edwards, 1881 (additional source)
Acanthistius Gill, 1862 (basis of record)
Acanthobothrium Blanchard, 1848 (additional source)
Acanthocarpus Stimpson, 1871 (additional source)
Acanthocepola Bleeker, 1874 (basis of record)
Acanthochaenus Gill, 1884 (additional source)
Acanthochiasma Krohn, 1861 (basis of record)
Acanthochondrites Oakley, 1930 (additional source)
Acanthocidaris Mortensen, 1903 (additional source)
Acanthocolpus Lühe, 1906 (basis of record)
Acanthocope Beddard, 1885 (additional source)
Acanthocorbis S.Hara & E.Takahashi, 1984 (additional source)
Acanthocotyle Monticelli, 1888 (additional source)
Acanthocybium Gill, 1862 (additional source)
Acanthocythereis Howe, 1963 (additional source)
Acanthodesia Canu & Bassler, 1919 accepted as Biflustra d'Orbigny, 1852 (basis of record)
Acanthogorgia Gray, 1857 (additional source)
Acantholaimus Allgén, 1933 (additional source)
Acanthomicrolaimus Stewart & Nicholas, 1987 (additional source)
Acanthomunna Beddard, 1886 (additional source)
Acanthomuricea Hentschel, 1903 (additional source)
Acanthonchus Cobb, 1920 (additional source)
Acanthonotozomella Schellenberg, 1926 (additional source)
Acanthonotozomoides Schellenberg, 1931 (additional source)
Acanthonotozomopsis Watling & Holman, 1980 (additional source)
Acanthonyx Latreille, 1828 (additional source)
Acanthopharyngoides Chitwood, 1936 (additional source)
Acanthopharynx Marion, 1870 (additional source)
Acanthophrys A. Milne-Edwards, 1865 (additional source)
Acanthoplesiops Regan, 1912 (basis of record)
Acanthopriapulus van der Land, 1970 (additional source)
Acanthoscina Vosseler, 1900 (additional source)
Acanthosquilla Manning, 1963 (basis of record)
Acanthostepheia Boeck, 1871 (additional source)
Acanthostomum Looss, 1899 (additional source)
Acanthostracion Bleeker, 1865 (additional source)
Acasta Leach, 1817 (additional source)
Acaudina H.L. Clark, 1908 (additional source)
Acaulis Stimpson, 1853 (additional source)
Acauloides Bouillon, 1965 (additional source)
Accacladocoelium Odhner, 1928 (additional source)
Accacoelium Monticelli, 1893 (additional source)
Accipiter Brisson, 1760 (basis of record)
Acentrogobius Bleeker, 1874 (basis of record)
Aceroides G.O. Sars, 1892 (additional source)
Acetabulastoma Schornikov, 1970 (additional source)
Achaeopsis Stimpson, 1857 (additional source)
Achelia Hodge, 1864 (additional source)
Acheliana Arnaud, 1971 (additional source)
Achelous De Haan, 1833 (additional source)
Achoronemertes Crandall & Gibson, 1997 (basis of record)
Acineta Ehrenberg, 1834 (additional source)
Acmira Hartley, 1981 accepted as Aricidea (Acmira) Hartley, 1981 (additional source)
Acmostomum Schmarda, 1859 (additional source)
Acreichthys Fraser-Brunner, 1941 (basis of record)
Acrocalanus Giesbrecht, 1888 (additional source)
Acrocirrus Grube, 1873 (additional source)
Acromitus Light, 1914 (basis of record)
Acrophytum Hickson, 1900 (additional source)
Acrorhynchides Strand, 1928 (additional source)
Acryptolaria Norman, 1875 (additional source)
Actaeomorpha Miers, 1877 (additional source)
Actaletes Giard, 1889 (additional source)
Acteonemertes Pantin, 1961 (additional source)
Acthelmis Lütken, 1875 (additional source)
Actidium Matthews, 1868 (additional source)
Actinarctus Schulz, 1935 (additional source)
Actinernus Verrill, 1879 (additional source)
Actinioides Haddon & Shackleton, 1893 (additional source)
Actinocythereis Puri, 1953 (additional source)
Actinonema Cobb, 1920 (additional source)
Actinoposthia An der Lan, 1936 (additional source)
Actinoptilum Kükenthal, 1911 (additional source)
Actinopyga Bronn, 1860 (additional source)
Actinoscyphia Stephenson, 1920 (additional source)
Actinostola Verrill, 1883 (additional source)
Actitis lliiger, 1811 (additional source)
Actumnus Dana, 1851 (additional source)
Aculeorhynchus Schilke, 1969 (additional source)
Adagnesia Kott, 1963 (additional source)
Adelopora Cairns, 1982 (additional source)
Adelosina d'Orbigny, 1826 (additional source)
Adelphos Ott, 1997 (additional source)
Adenocauda Dörjes, 1968 (additional source)