• Abyssonemertes kajiharai Chernyshev & Polyakova, 2017: epizoic
• Acanthomolgus ambonensis Kim I.H., 2007: symbiotic
• Acanthomolgus bandaensis Kim I.H., 2007: symbiotic
• Acanthomolgus dispadactylus Kim I.H., 2007: symbiotic
• Acanthomolgus exilipes (Humes & Ho, 1968): symbiotic
• Acanthomolgus gentilis (Humes & Ho, 1968): symbiotic
• Acanthomolgus gomumuensis Kim I.H., 2007: symbiotic
• Acanthomolgus longispinifer (Humes & Ho, 1968): symbiotic
• Acanthomolgus tenuispinatus Kim I.H., 2009: symbiotic
• Acanthomolgus varirostratus (Humes & Ho, 1968): symbiotic
• Acharax alinae Métivier & Cosel, 1993: with chemosymbionts
• Acharax bartschii (Dall, 1908): with chemosymbionts
• Acharax burica (Olsson, 1942) †: with chemosymbionts
• Acharax caribbaea (H. E. Vokes, 1970): with chemosymbionts
• Acharax clarificata Dell, 1995: with chemosymbionts
• Acharax cretacea Kanie & Nishida, 2000 †: with chemosymbionts
• Acharax doderleini (Mayer, 1861) †: with chemosymbionts
• Acharax frenademezi Prinoth & Posenato, 2023 †: with chemosymbionts
• Acharax gadirae P. G. Oliver, Rodrigues & M. Cunha, 2011: with chemosymbionts
• Acharax gigas (Kanno, 1960) †: with chemosymbionts
• Acharax grandis (A. E. Verrill & K. J. Bush, 1898): with chemosymbionts
• Acharax haimaensis M. Yang, B.-Q. Li, Z.-B. Gan, D. Dong & X.-Z. Li, 2024: with chemosymbionts
• Acharax johnsoni (Dall, 1891): with chemosymbionts
• Acharax mikasaensis Kiel, Amano & R. G. Jenkins, 2008 †: with chemosymbionts
• Acharax muroensis (Natori, 1964) †: with chemosymbionts
• Acharax patagonica (E. A. Smith, 1885): with chemosymbionts
• Acharax peteri (Zinsmeister, 1984) †: with chemosymbionts
• Acharax prashadi (H. E. Vokes, 1955): with chemosymbionts
• Acharax primaeva (J. Phillips, 1836) †: with chemosymbionts
• Acharax stantoni (H. E. Vokes, 1955) †: with chemosymbionts
• Acharax subquadrata (Foresti, 1879) †: with chemosymbionts
• Acharax subventricosta Krishtofovich, 1984 †: with chemosymbionts
• Acharax svalbardensis Hansen, Ezat, Åström & Rasmussen, 2019 †: with chemosymbionts
• Acharax ventricosa (Conrad, 1849) †: with chemosymbionts
• Acharax yessoensis (Kanehara, 1937) †: with chemosymbionts
• Acharax yokosukensis Kanie & Kuramochi, 1995 †: with chemosymbionts
• Achoronemertes scoresbyi (Wheeler, 1934): epizoic
• Acteonemertes bathamae Pantin, 1961: epizoic
• Acteonemertes orientalis Hookabe, Fujino, Jimi & Ueshima, 2023: epizoic
• Aegialonemertes chlorophthalma Gibson, 1990: epizoic
• Aenigmanemertes norenburgi Sundberg & Gibson, 1995: epizoic
• Africanemertes ruetzleri Kirsteuer, 1965: epizoic
• Africanemertes swakopmundi Stiasny-Wijnhoff, 1942: epizoic
• Aglaogastes cnidicus (Humes, 1981): symbiotic
• Akrostomum stannii Grube, 1840: epizoic
• Akrostomum valdiviae (Bürger, 1909): epizoic
• Alaonemertes michaelseni Stiasny-Wijnhoff, 1942: epizoic
• Alaxinus oclairi Gibson, Wickham & Kuris, 1990: epizoic
• Albanemertes rovinjensis Senz, 1993: epizoic
• Alcyonosyllis aidae Álvarez-Campos, San Martín & Aguado, 2013: symbiotic
• Alexandronemertes ductor Chernyshev, 1992: epizoic
• Alexandronemertes mollis (Coe, 1926): epizoic
• Algonemertes alba Corrêa, 1954: epizoic
• Alococoncha crassatellaeformis (Tate, 1896) †: with chemosymbionts
• Alteuthoides affinis Kim S.H. & Kim W., 1998: symbiotic
• Alteuthoides kootare Hicks, 1986: symbiotic
• Alvinonemertes dariae Sagorny, von Döhren, Rouse & Tilic, 2022: epizoic
• Alvinonemertes tilici Chernyshev & Kuznetsov, 2025: epizoic
• Amarda curvus Kim I.H., 2007: symbiotic
• Ammonemertes erseusi Gibson, 1990: epizoic
• Amphiascus soyeri (Lang, 1965): symbiotic
• Amphinemertes caeca (Coe, 1901): epizoic
• Amphipholis conolampadis Kroh & Thuy, 2013: epizoic
• Amphiporus allucens Bürger, 1895: epizoic
• Amphiporus angulatus (Müller, 1774): epizoic
• Amphiporus antifuscus Iwata, 1954: epizoic
• Amphiporus binocellatus Senz, 1993: epizoic
• Amphiporus brunneus Griffin, 1898: epizoic
• Amphiporus californicus Coe, 1905: epizoic
• Amphiporus cruciatus Bürger, 1893: epizoic
• Amphiporus cruentatus Verrill, 1879: epizoic
• Amphiporus delta Joubin, 1902: epizoic
• Amphiporus dissimulans Riches, 1893: epizoic
• Amphiporus exilis Coe, 1901: epizoic
• Amphiporus flavescens Coe, 1905: epizoic
• Amphiporus formidabilis Griffin, 1898: epizoic
• Amphiporus fulvus Coe, 1905: epizoic
• Amphiporus fuscosparus Korotkevich, 1977: epizoic
• Amphiporus gelatinosus Coe, 1905: epizoic
• Amphiporus gerlachei Bürger, 1904: epizoic
• Amphiporus glandulosus Bürger, 1895: epizoic
• Amphiporus greenmani Montgomery, 1897: epizoic
• Amphiporus griseus (Stimpson, 1855): epizoic
• Amphiporus heterosorus Verrill, 1892: epizoic
• Amphiporus imparispinosus Griffin, 1898: epizoic
• Amphiporus incubator Joubin, 1914: epizoic
• Amphiporus inexpectatus Wheeler, 1934: epizoic
• Amphiporus japonicus (Stimpson, 1857): epizoic
• Amphiporus lecointei Bürger, 1904: epizoic
• Amphiporus leptacanthus Coe, 1905: epizoic
• Amphiporus leuciodus Coe, 1901: epizoic
• Amphiporus macracanthus Coe, 1905: epizoic
• Amphiporus maculosus Coe, 1944: epizoic
• Amphiporus mathai Joubin, 1905: epizoic
• Amphiporus matuanus Korotkevich, 1977: epizoic
• Amphiporus mesosorus Verrill, 1892: epizoic
• Amphiporus mortonmilleri Gibson, 2002: epizoic
• Amphiporus moseleyi Hubrecht, 1887: epizoic
• Amphiporus multihastatus Joubin, 1910: epizoic
• Amphiporus multisorus Verrill, 1892: epizoic