Dodatak:Popis žarnjaka, O
Ob uredi
Obelia Péron & Lesueur, 1810 uredi
- Obelia bidentata Clark, 1875
- Obelia castellata Clarke, 1894
- Obelia dichotoma (Linnaeus, 1758)
- Obelia diversa (Fraser, 1948)
- Obelia geniculata (Linnaeus, 1758)
- Obelia irregularis Fraser, 1943
- Obelia longissima (Pallas, 1766)
- Obelia spongicola Watson, 2011
- Obelia striata Clarke, 1907
Animalia → Cnidaria → Hydrozoa → Leptothecata → Campanulariidae
Oc uredi
- Oceania
- Oceaniidae
- Octineon
- Octineonidae
- Octocannoides
- Octocannoididae
- Octogonade
- Octophialucium
- Octorathkea
- Octorradiata
- Octotiara
- Octovannuccia
- Oculina
- Oculinidae
Od uredi
- Odessia
Og uredi
†Ogilviastraea Oppenheim, 1930 uredi
- †Ogilviastraea bigemmis Felix 1903 [1]
- †Ogilviastraea richardsi Wells 1933 [1]
Cnidaria → Anthozoa → Scleractinia → Agariciicae → Agariciidae
Ok uredi
†Okopites Bondarenko 1978 uredi
- Okopites confluens Deng & Yang. D.-r. 1983
- Okopites hefengensis Deng Zhanqiu 1999
- Okopites okopinensis Bondarenko 1978
- Okopites okopinensis okopinensis
- Okopites okopinensis uniformis Bondarenko 1978
- Okopites subtilis Deng & Yang. D.-r. 1983
Cnidaria → Anthozoa → Heliolitida → Heliolitidae
Ol uredi
- Olindagorgia
- Olindias
- Olindiidae
†Ondadiplocteniopsis Zlatarski 1968 uredi
Cnidaria → Anthozoa → Scleractinia
On uredi
- Onogorgia
Op uredi
- Oparinisis
- Opercularella
- Ophidiogorgia
- Ophinella
- Ophiodiscus
- Oplorhiza
Or uredi
Oractis McMurrich, 1893 uredi
- Oractis bursifera Riemann-Zürneck, 2000
- Oractis diomedeae McMurrich, 1893
Cnidaria → Anthozoa → Actiniaria → Haloclavidae
- Orangaslia
- Orchistoma
- Orchistomatidae
- Orchistomella
- Orinia
- Orlikia
- Orstomisis
- Orthopyxis
Os uredi
- Oswaldella
Ot uredi
- Otohydra
- Otohydridae
- Otoporpa
Ou uredi
- Oulactis
- Oulangia
- Oulastrea
- Oulophyllia
Ov uredi
Ovabunda Alderslade, 2001 uredi
- Ovabunda ainex (Reinicke, 1997)
- Ovabunda andamanensis Janes, McFadden & Chanmethakul, 2014
- Ovabunda arabica (Reinicke, 1995)
- Ovabunda benayahui (Reinicke, 1995)
- Ovabunda biseriata (Verseveldt & Cohen, 1971)
- Ovabunda crenata (Reinicke, 1997)
- Ovabunda faraunenesis (Verseveldt & Cohen, 1971)
- Ovabunda gohari (Reinicke, 1997)
- Ovabunda hamsina (Reinicke, 1997)
- Ovabunda impulsatilla (Verseveldt & Cohen, 1971)
- Ovabunda macrospiculata (Gohar, 1940)
- Ovabunda obscuronata (Verseveldt & Cohen, 1971)
- Ovabunda verseveldti (Benayahu, 1990)
Cnidaria → Anthozoa → Alcyonacea → Alcyoniina → Xeniidae
Ovactis Van Beneden, 1897 uredi
- Ovactis aequatorialis van Beneden, 1897
- Ovactis bermudensis van Beneden, 1897
- Ovactis brasiliensis van Beneden, 1897
- Ovactis canariensis Gravier, 1920
- Ovactis wilsoni van Beneden, 1897
Cnidaria → Anthozoa → Ceriantharia → Penicilaria → Arachnactidae
Ovanthula Van Beneden, 1924 uredi
- Ovanthula apoda Van Beneden, 1924
Cnidaria → Anthozoa → Ceriantharia → Spirularia → Botrucnidiferidae
Ox uredi
Oxypora Saville-Kent, 1871 uredi
- Oxypora aspera (Ellis & Solander, 1768)
- Oxypora convoluta Veron, 2000
- Oxypora crassispinosa Nemenzo, 1979
- Oxypora egyptensis Veron, 2000
- Oxypora glabra Nemenzo, 1959
- Oxypora lacera (Verrill, 1864)
Animalia → Cnidaria → Anthozoa → Scleractinia → Lobophylliidae
Oxysmilia Duchassaing, 1870 uredi
- Oxysmilia corrugata Cairns, 1999
- Oxysmilia rotundifolia (Milne Edwards & Haime, 1848)
Animalia → Cnidaria → Anthozoa → Scleractinia → Caryophylliidae