• Abludomelita aculeata (Chevreux, 1911)
• Abludomelita gladiosa (Spence Bate, 1862)
• Abludomelita obtusata (Montagu, 1813)
• Abludomelita richardi (Chevreux, 1900)
• Abyssocythere carpathica Pokorny, 1975 †
• Abyssorchomene abyssorum (Stebbing, 1888)
• Abyssorchomene chevreuxi (Stebbing, 1906)
• Abyssorchomene gerulicorbis (Shulenberger & Barnard, 1976)
• Acaenomolgus protulae (Stock, 1959)
• Acaenomolgus serpulae (Stock, 1960)
• Acantharctus posteli (Forest, 1963)
• Acanthaspidia decorata (Hansen, 1895) accepted as Iolanthe decorata Hansen, 1895
• Acanthaspidia laevis Chardy, 1975 accepted as Iolanthe laevis (Chardy, 1975)
• Acanthaspidia typhlops (G. O. Sars, 1879) accepted as Iolanthe typhlops (G. O. Sars, 1879)
• Acanthephyra brevirostris Smith, 1885
• Acanthephyra curtirostris Wood-Mason in Wood-Mason & Alcock, 1891
• Acanthephyra eximea Smith, 1884 accepted as Acanthephyra eximia Smith, 1884
• Acanthephyra eximia Smith, 1884
• Acanthephyra pelagica (Risso, 1816)
• Acanthephyra purpurea A. Milne-Edwards, 1881
• Acanthephyra stylorostratis (Spence Bate, 1888)
• Acanthephyra tenuipes (Spence Bate, 1888)
• Acanthocarpus brevispinis Monod, 1946
• Acanthochondria clavata (Bassett-Smith, 1896)
• Acanthochondria cornuta (Müller O.F., 1776)
• Acanthochondria limandae (Krøyer, 1863)
• Acanthochondria soleae (Krøyer, 1838)
• Acanthochondria triglae Herrera-Cubilla & Raibaut, 1990
• Acanthochondrites annulatus (Olsson, 1869)
• Acanthocope annulatus Menzies, 1962
• Acanthocope armata Chardy, 1972
• Acanthocope carinata Chardy, 1972
• Acanthocythereis ascolii (Puri, 1963) †
• Acanthocythereis dunelmensis (Norman, 1865) accepted as Actinocythereis dunelmensis (Norman, 1865)
• Acanthocythereis hystrix (Reuss, 1850) Sissingh, 1972 †
• Acanthocythereis ornata (Müller, 1894)
• Acanthomunna hystrix (Hansen, 1916)
• Acanthomysis longicornis (Milne Edwards, 1837)
• Acanthomysis strauchi (Czerniavsky, 1882) accepted as Paramysis (Metamysis) ullskyi Czerniavsky, 1882
• Acanthonotozoma cristatum (Ross, 1835)
• Acanthonotozoma inflatum (Krøyer, 1842)
• Acanthonotozoma magnum Just, 1978
• Acanthonotozoma monodentatum Kudrjaschov, 1965
• Acanthonotozoma rusanovae Bryazgin, 1974
• Acanthonotozoma serratum (O. Fabricius, 1780)
• Acanthonotozoma sinuatum Just, 1978
• Acanthonotus owenii Spence Bate, 1857 accepted as Epimeria cornigera (Fabricius, 1779) accepted as Epimeria (Epimeria) cornigera (Fabricius, 1779)
• Acanthonotus testudo White, 1850 accepted as Epimeria cornigera (Fabricius, 1779) accepted as Epimeria (Epimeria) cornigera (Fabricius, 1779)
• Acanthonyx brevifrons A. Milne-Edwards, 1869
• Acanthonyx lunulatus (Risso, 1816)
• Acanthoscina acanthodes (Stebbing, 1895)
• Acanthostepheia behringiensis (Lockington, 1877)
• Acanthostepheia incarinata Gurjanova, 1929
• Acanthostepheia malmgreni (Goës, 1866)
• Acanthozone cuspidata (Ross, 1835) accepted as Paramphithoe hystrix (Ross, 1835)
• Acartia (Acanthacartia) bifilosa (Giesbrecht, 1881)
• Acartia (Acanthacartia) fossae Gurney, 1927
• Acartia (Acanthacartia) italica Steuer, 1910
• Acartia (Acanthacartia) plumosa Scott T., 1894
• Acartia (Acanthacartia) tonsa Dana, 1849
• Acartia (Acartia) danae Giesbrecht, 1889
• Acartia (Acartia) negligens Dana, 1849
• Acartia (Acartiura) clausi Giesbrecht, 1889
• Acartia (Acartiura) discaudata (Giesbrecht, 1881)
• Acartia (Acartiura) enzoi Crisafi, 1974
• Acartia (Acartiura) lefevreae Bradford, 1976
• Acartia (Acartiura) longiremis (Lilljeborg, 1853)
• Acartia (Acartiura) margalefi Alcaraz, 1976
• Acartia (Acartiura) teclae Bradford, 1976
• Acartia (Hypoacartia) adriatica Steuer, 1910
• Acartia (Odontacartia) centrura Giesbrecht, 1889
• Acartia adriatica Steuer, 1910 represented as Acartia (Hypoacartia) adriatica Steuer, 1910
• Acartia bifilosa (Giesbrecht, 1881) represented as Acartia (Acanthacartia) bifilosa (Giesbrecht, 1881)
• Acartia centrura Giesbrecht, 1889 represented as Acartia (Odontacartia) centrura Giesbrecht, 1889
• Acartia clausi Giesbrecht, 1889 represented as Acartia clausii Giesbrecht, 1889 represented as Acartia (Acartiura) clausi Giesbrecht, 1889
• Acartia clausii Giesbrecht, 1889 represented as Acartia (Acartiura) clausi Giesbrecht, 1889
• Acartia danae Giesbrecht, 1889 represented as Acartia (Acartia) danae Giesbrecht, 1889
• Acartia discaudata (Giesbrecht, 1882) represented as Acartia (Acartiura) discaudata (Giesbrecht, 1881)
• Acartia enzoi Crisafi, 1974 represented as Acartia (Acartiura) enzoi Crisafi, 1974
• Acartia fossae Gurney, 1927 represented as Acartia (Acanthacartia) fossae Gurney, 1927
• Acartia grani Sars G.O., 1904 accepted as Paracartia grani Sars G.O., 1904 represented as Paracartia grani grani Sars G.O., 1904
• Acartia italica Steuer, 1910 represented as Acartia (Acanthacartia) italica Steuer, 1910
• Acartia latisetosa (Krichagin, 1873) accepted as Paracartia latisetosa (Krichagin, 1873)
• Acartia lefevreae Bradford, 1976 represented as Acartia (Acartiura) lefevreae Bradford, 1976
• Acartia longiremis (Lilljeborg, 1853) represented as Acartia (Acartiura) longiremis (Lilljeborg, 1853)
• Acartia margalefi Alcaraz, 1976 represented as Acartia (Acartiura) margalefi Alcaraz, 1976
• Acartia negligens Dana, 1849 represented as Acartia (Acartia) negligens Dana, 1849
• Acartia plumosa Scott T., 1894 represented as Acartia (Acanthacartia) plumosa Scott T., 1894
• Acartia teclae Bradford, 1976 represented as Acartia (Acartiura) teclae Bradford, 1976
• Acartia tonsa Dana, 1849 represented as Acartia (Acanthacartia) tonsa Dana, 1849
• Acasta cyathus Darwin, 1854
• Acasta spongites (Poli, 1791)
• Aceroides (Aceroides) goesi Just, 1980
• Aceroides (Aceroides) latipes (G.O. Sars, 1883)
• Aceros phyllonyx (M. Sars, 1858) accepted as Arrhis phyllonyx (M. Sars, 1858)
• Acetabulastoma hyperboreum (Scott, 1899)
• Achaeus cranchii Leach, 1817
• Achaeus gracilis (O.G. Costa, 1839)
• Achelous hastatus (Linnaeus, 1767)
• Achelous inaequalis (Miers, 1881)