Abietinaria Kirchenpauer, 1884 (additional source)
Abludomelita Karaman, 1981 (additional source)
Abludomelita gladiosa (Spence Bate & Westwood, 1862) (additional source)
Abludomelita obtusata (Montagu, 1813) (additional source)
Acanthochitona communis (Risso, 1826) accepted as Acanthochitona fascicularis (Linnaeus, 1767) (basis of record)
Acanthochitona gracilis (Jeffreys, 1859) accepted as Acanthochitona crinita (Pennant, 1777) (source of synonymy)
Acanthocythereis dunelmensis (Norman, 1865) accepted as Actinocythereis dunelmensis (Norman, 1865) (additional source)
Acanthodasys Remane, 1927 (additional source)
Acanthodasys aculeatus Remane, 1927 (additional source)
Acanthodasys arcassonensis Kisielewski, 1987 (additional source)
Acteon tornatilis (Linnaeus, 1758) (additional source)
Actinauge Verrill, 1883 (additional source)
Actinauge richardi (Marion, 1906) (additional source)
Aega Leach, 1816 (additional source)
Aegires punctilucens (A. d'Orbigny, 1837) (additional source)
Aglantha digitale (O. F. Müller, 1776) (additional source)
Alcyonidiidae Johnston, 1837 (additional source)
Alcyonidium mytili Dalyell, 1848 accepted as Alcyonidioides mytili (Dalyell, 1848) (additional source)
Alvania beani [sic] accepted as Alvania beanii (Hanley, 1844) (additional source)
Anaitides citrina (Malmgren, 1865) accepted as Phyllodoce citrina Malmgren, 1865 (basis of record)
Anaitides groenlandica (Örsted, 1842) accepted as Phyllodoce groenlandica Örsted, 1842 (basis of record)
Anguinella palmata Van Beneden, 1845 (additional source)
Angulus tenuis (da Costa, 1778) accepted as Macomangulus tenuis (da Costa, 1778) (basis of record)
Anthuridae Leach, 1814 (additional source)
Antipathes Pallas, 1766 (additional source)
Antipathes subpinnata Ellis & Solander, 1786 accepted as Antipathella subpinnata (Ellis & Solander, 1786) (additional source)
Antipathidae Ehrenberg, 1834 (additional source)
Aphanodomus terebellae (Levinsen, 1878) (additional source)
Aphelochaeta multibranchiis [auct. lapsus] accepted as Aphelochaeta multibranchis (Grube, 1863) (basis of record)
Aplidium Savigny, 1816 (additional source)
Aplidium densum (Giard, 1872) (additional source)
Aplysia Linnaeus, 1767 (additional source)
Aponuphis Kucheruk, 1978 (additional source)
Aponuphis bilineata (Baird, 1870) (additional source)
Apseudes grossimanus Norman & Stebbing, 1886 (additional source)
Arachnidiidae Hincks, 1880 (additional source)
Arachnidium Hincks, 1859 (additional source)
Arachnidium fibrosum Hincks, 1880 (additional source)
Arca lactea Linnaeus, 1758 accepted as Striarca lactea (Linnaeus, 1758) (basis of record)
Archidistoma Garstang, 1891 (additional source)
Archidistoma aggregatum Garstang, 1891 (additional source)
Arcturella dilatata (G. O. Sars, 1883) accepted as Astacilla dilatata G. O. Sars, 1883 (additional source)
Arcturidae Dana, 1849 (additional source)
Aricidea (Aricidea) albatrossae Pettibone, 1957 (additional source)
Ascidia conchilega Müller, 1776 (additional source)
Ascidia mentula Müller, 1776 (additional source)
Ascidiella scabra (Müller, 1776) (additional source)
Aslia Rowe, 1970 (additional source)
Aspidelectra Levinsen, 1909 (additional source)
Aspidelectra melolontha (Landsborough, 1852) (additional source)
Aspidiophorus Voigt, 1903 (additional source)
Aspidiophorus bisquamosus Mock, 1979 (additional source)
Aspidiophorus marinus Remane, 1926 (additional source)
Aspidiophorus mediterraneus Remane, 1927 (additional source)
Aspidiophorus ornatus Mock, 1979 (additional source)
Aspidiophorus paramediterraneus Hummon, 1974 (basis of record)
Aspidoconcha limnoriae de Vos, 1953 (additional source)
Asplanchna Gosse, 1850 (additional source)
Astacilla intermedia (Goodsir, 1841) (additional source)
Astarte triangularis (Montagu, 1803) accepted as Goodallia triangularis (Montagu, 1803) (basis of record)
Atollidae Hickson, 1906 (additional source)
Atylus guttatus (A. Costa in Hope, 1851) accepted as Nototropis guttatus (A. Costa in Hope, 1851) (additional source)
Aurelia Lamarck, 1816 (additional source)
Aurelia aurita (Linnaeus, 1758) (additional source)
Autonoe Bruzelius, 1859 (additional source)
Autonoe denticarpus (Myers & McGrath, 1978) (additional source)
Autonoe longipes (Liljeborg, 1852) (additional source)
Balanus Costa, 1778 (additional source)
Beania Johnston, 1840 (additional source)
Beania mirabilis Johnston, 1840 (additional source)
Beaniidae Canu & Bassler, 1927 (additional source)
Bela laevigata (R. A. Philippi, 1836) accepted as Bela zonata (Locard, 1891) (additional source)
Biemna Gray, 1867 (additional source)
Biemna variantia (Bowerbank, 1858) (additional source)
Biserramenia psammobionta Salvini-Plawen, 1967 (additional source)
Boccardiella Blake & Kudenov, 1978 (additional source)
Boccardiella ligerica (Ferronnière, 1898) (additional source)
Bopyrus squillarum Latreille, 1804 accepted as Bopyrus crangorum (Fabricius, 1798) (additional source)
Botrylloides leachi (Savigny, 1816) accepted as Botrylloides leachii (Savigny, 1816) (additional source)
Botryllophilus norvegicus Schellenberg, 1921 (additional source)
Brachycalanus Farran, 1905 (additional source)
Brachycalanus atlanticus (Wolfenden, 1904) (additional source)
Bursovaginoidea (basis of record)
Byblis Boeck, 1871 (additional source)
Byblis erythrops G.O. Sars, 1883 (additional source)
Byblis gaimardi (Krøyer, 1846) accepted as Byblis gaimardii (Krøyer, 1846) (additional source)
Bythocythere robinsoni Athersuch, Horne & Whittaker, 1983 (additional source)
Callistocythere badia (Norman, 1862) (additional source)
Callochiton achatinus (T. Brown, 1823) accepted as Callochiton septemvalvis (Montagu, 1803) (additional source)
Calycella Hincks, 1864 in Allman, 1864 (additional source)
Calycella gracilis Hartlaub, 1897 (additional source)
Calycella hispida (Nutting, 1896) (basis of record)
Campanulina Van Beneden, 1847 (basis of record)
Campanulina panicula G.O. Sars, 1874 accepted as Earleria panicula (G.O. Sars, 1874) (basis of record)
Campanulina pumila (Clark, 1875) (basis of record)
Campanulinidae Hincks, 1868 (basis of record)
Campylaspis costata (Sars, 1865) (additional source)
Campylaspis glabra Sars, 1878 (additional source)
Campylaspis legendrei Fage, 1951 (additional source)
Campylaspis macrophthalma Sars, 1878 (additional source)

Europe for Myriothelidae Hincks, 1868 
Europe for Zoantharia 

 Synonymy

 for Lasaea adansoni (Gmelin, 1791)

Synonym of Lasaea rubra [details]