• Aaptos aaptos (Schmidt, 1864)
• Aaptos conferta Kelly-Borges & Bergquist, 1994
• Aaptos horrida (Carter, 1886)
• Aaptos papillata (Keller, 1880)
• Aaptos tentum Kelly-Borges & Bergquist, 1994 accepted as Aaptos tenta Kelly-Borges & Bergquist, 1994
• Abyssocladia bruuni Lévi, 1964
• Abyssocladia falkor Ekins & Hooper, 2023
• Abyssocladia jeanvaceleti Ekins & Hooper, 2023
• Abyssocladia microstrongylata Vacelet, 2020
• Abyssocladia rowdeni Kelly & Vacelet, 2023
• Abyssocladia villosa Hestetun, Rapp & Pomponi, 2019
• Acanthacarnus souriei Lévi, 1952 accepted as Acarnus souriei (Lévi, 1952)
• Acanthascus (Acanthascus) alani Ijima, 1898
• Aaptos adriatica Gray, 1867 accepted as Aaptos aaptos (Schmidt, 1864)
• Aaptos durissima (Carter, 1882)
• Aaptos lithophaga (Wiedenmayer, 1977) accepted as Aaptos pernucleata (Carter, 1870)
• Aaptos robustus Plotkin & Janussen, 2008
• Abila freyerii (Schmidt, 1862) accepted as Raspailia (Raspailia) viminalis Schmidt, 1862
• Abyssocladia corniculiphora Hestetun, Rapp & Xavier, 2017
• Abyssocladia fryerae Hestetun, Rapp & Pomponi, 2019
• Abyssocladia koltuni (Ereskovsky & Willenz, 2007)
• Abyssocladia natsushimae Ise & Vacelet, 2010
• Abyssocladia symmetrica (Ridley & Dendy, 1886)
• Acamas laxissima Duchassaing & Michelotti, 1864 accepted as Mycale (Arenochalina) laxissima (Duchassaing & Michelotti, 1864)
• Acanthancora coralliophila van Soest, 1984
• Aaptos aaptos var. nigra Topsent, 1934
• Aaptos duchassaingi (Topsent, 1889)
• Aaptos laxosuberites (Sollas, 1902)
• Aaptos potiguarensis Carvalho, da Silva & Pinheiro, 2013
• Aaptos vannamei de Laubenfels, 1935
• Abyssocladia claviformis Koltun, 1970
• Abyssocladia flagrum (Lehnert, Stone & Heimler, 2006)
• Abyssocladia kellyae Hestetun, Rapp & Pomponi, 2019
• Abyssocladia myojinensis Ise & Vacelet, 2010
• Abyssocladia stegosaurensis Hestetun, Rapp & Pomponi, 2019
• Acalle recurvata (Bowerbank, 1863)
• Acanthancora clavatancora Topsent, 1927 accepted as Pseudohalichondria clavatancora (Topsent, 1927)
• Aaptos bergmanni de Laubenfels, 1950
• Aaptos globosum Kelly-Borges & Bergquist, 1994 accepted as Aaptos globosa Kelly-Borges & Bergquist, 1994
• Aaptos niger Hoshino, 1981 accepted as Aaptos nigra Hoshino, 1981
• Aaptos simplex (Lambe, 1893)
• Abyssocladia antarctica Buskowiak & Janussen, 2021
• Abyssocladia diegoramirezensis Lopes, Bravo & Hajdu, 2011
• Abyssocladia hemiradiata Hestetun, Rapp & Xavier, 2017
• Abyssocladia lanceola Kelly & Vacelet, 2023
• Abyssocladia oxeata Koltun, 1970
• Abyssocladia tumulorum Kelly & Vacelet, 2023
• Acamasina laxissima (Duchassaing & Michelotti, 1864) accepted as Mycale (Arenochalina) laxissima (Duchassaing & Michelotti, 1864)
• Acanthancora equiformis Sim-Smith, Hickman & Kelly, 2021
• Aaata spongigartina de Laubenfels, 1930 accepted as Clathria (Microciona) spongigartina (de Laubenfels, 1930)
• Aaptos ciliata (Wilson, 1925)
• Aaptos hajdui Carvalho, da Silva & Pinheiro, 2013
• Aaptos nuda (Kirkpatrick, 1903)
• Aaptos tenta Kelly-Borges & Bergquist, 1994
• Abyssocladia boletiphora Hestetun, Rapp & Xavier, 2017
• Abyssocladia escheri Ekins, Erpenbeck & Hooper, 2020
• Abyssocladia inflata Vacelet, 2006
• Abyssocladia marianensis Hestetun, Rapp & Pomponi, 2019
• Abyssocladia polycephalus Hestetun, Pomponi & Rapp, 2016
• Abyssocladia vaceleti Ríos & Cristobo, 2018
• Acanthacarnus radovani Boury-Esnault, 1973 accepted as Acarnus radovani (Boury-Esnault, 1973)
• Acanthancora stylifera Burton, 1959
• Aaata brepha Laubenfels, 1930 accepted as Clathria (Microciona) brepha (de Laubenfels, 1930)
• Aaptos chromis de Laubenfels, 1954 accepted as Aaptos suberitoides (Brøndsted, 1934)
• Aaptos glutinans Moraes, 2011
• Aaptos nigra Hoshino, 1981
• Aaptos suberitoides (Brøndsted, 1934)
• Abyssocladia atlantica Lopes & Hajdu, 2014
• Abyssocladia dominalba Vacelet, 2006
• Abyssocladia huitzilopochtli Vacelet, 2006
• Abyssocladia leverhulmei Goodwin, Berman, Downey & Hendry, 2017
• Abyssocladia oxyasters Ekins, Erpenbeck, Goudie & Hooper, 2020
• Abyssocladia umbellata Lopes, Bravo & Hajdu, 2011
• Acanthacarnus levii Vacelet, 1960 accepted as Acarnus levii (Vacelet, 1960)
• Acanthancora schmidti (Topsent, 1898)
• Aaptos alphiensis Samaai & Gibbons, 2005
• Aaptos globosa Kelly-Borges & Bergquist, 1994
• Aaptos lobata Calcinai, Bastari, Bertolino & Pansini, 2017
• Aaptos rosacea Kelly-Borges & Bergquist, 1994
• Abyssocladia annae Ekins, Erpenbeck & Hooper, 2020
• Abyssocladia desmophora (Hooper & Lévi, 1989)
• Abyssocladia gliscofila Ekins, Erpenbeck & Hooper, 2020
• Abyssocladia lakwollii Vacelet & Kelly, 2014
• Abyssocladia naudur Vacelet, 2006
• Abyssocladia tecta Hestetun, Fourt, Vacelet, Boury-Esnault & Rapp, 2015
• Acamas violacea Duchassaing & Michelotti, 1864 accepted as Hyrtios violaceus (Duchassaing & Michelotti, 1864)
• Acanthancora cyanocrypta (de Laubenfels, 1930)
• Aaptos aaptos var. nigra Lévi, 1961 accepted as Aaptos suberitoides (Brøndsted, 1934)
• Aaptos confertus Kelly-Borges & Bergquist, 1994 accepted as Aaptos conferta Kelly-Borges & Bergquist, 1994
• Aaptos kanuux Lehnert, Hocevar & Stone, 2008
• Aaptos pernucleata (Carter, 1870)
• Aaptos unispiculus (Carter, 1880) accepted as Eurypon unispiculum (Carter, 1880)
• Abyssocladia carcharias Kelly & Vacelet, 2011
• Abyssocladia faranauti Hestetun, Fourt, Vacelet, Boury-Esnault & Rapp, 2015
• Abyssocladia kanaconi Vacelet, 2020
• Abyssocladia mucronata Vacelet, 2020 accepted as Echinostylinos gorgonopsis Lévi, 1993
• Abyssocladia sonnae Kelly & Vacelet, 2023
• Abyssosdiskos pentaeiros (Ekins, Erpenbeck & Hooper, 2020)
• Acanthancora aenigma (Lundbeck, 1910)
• Acanthascus (Acanthascus) alani alani Ijima, 1898