List compiled by Marta Ronowicz (IO PAS), verified by Peter Schuchert (Natural History Museum, Geneva)

4.11. List of the Hydrozoa from Hornsund (2003 and 2006)
 
Class: Hydrozoa
Order: Leptomedusae
Suborder: Conica

Family: Campanulinidae
Calycella syringa (Linnaeus, 1767)
Campanulina pumila (G.O. Sars, 1874)
Cuspidella procumbens (Alder, 1863)
Cuspidella sp.
Lafoeina maxima (Levinsen, 1893)
Family: Haleciidae
Halecium arcticum Ronowicz & Schuchert, 2007
Halecium beani (Johnston, 1838)
Halecium curvicaule Lorenz, 1886
Halecium minutum Broch, 1903
Halecium mirabile Schydlowsky, 1902
Halecium muricatum (Ellis & Solander, 1786)
Halecium cf. speciosum Nutting, 1901
Halecium textum Kramp, 1911
Family: Lafoeidae
Filellum serpens (Hassall, 1848)
Grammaria abietina (M. Sars, 1851)
Lafoea dumosa (Fleming, 1828)
Family: Phialellidae
Opercularella lacerata (Johnston, 1847)
Family: Plumularioidae
Plumularia setacea (Linnaeus, 1758)
Family: Sertulariidae
Abietinaria pulchra (Nutting, 1904)
Sertularella rugosa (Alder, 1857)
Sertularella tenella (Alder, 1857)
Sertularia cf. albimaris Mereschowsky, 1878
Sertularia argentea Linnaeus, 1758
Sertularia cupressoides Clark, 1876
Sertularia cupressina Linnaeus, 1758
Sertularia mirabilis (Verrill, 1873)
Sertularia fabricii Levinsen, 1893
Sertularia schmidti Kudelin, 1914
Sertularia cf. similis Clark, 1877
Symplectoscyphus tricuspidatus (Alder, 1856)
Tamarisca tamarisca (Linnaeus, 1758)
Family: Tiarannidae
Stegopoma plicatile (M. Sars, 1863)
Suborder: Proboscidoidea
Family: Campanulariidae
Campanularia integra MacGillivray, 1842
Campanularia volubilis (Linnaeus, 1758)
Gonothyrea loveni (Allman, 1859)
Obelia longissima (Pallas, 1766)
Rhizocaulus verticillatus (Linnaeus, 1758)
Order: Anthomedusae
Suborder: Filifera
Family: Eudendriidae
Eudendrium album Nutting, 1898
Eudendrium annulatum Norman, 1864
Eudendrium cf. capillare Alder, 1856
Eudendrium insigne Hincks, 1861
Eudendrium rameum (Pallas, 1766)
Eudendrium ramosum (Linnaeus, 1758)
Eudendrium vaginatum Allman, 1863
Family: Bougainvillidae
Bougainvilia cf. superciliaris
Rhizorhagium roseum Sars, 1874
Family: Hydractiniidae
Hydractinia carica
Hydractinia sp.
Family: Oceaniidae
Rhizogeton nudus Broch, 1909
Suborder: Capitata
Family: Corynidae
Sarsia loveni (M. Sars, 1846)