title: Hydractinia
text: # Hydractinia
  
  Hydractinia Van Beneden, 1841 è un genere di Hydrozoa della famiglia Hydractiniidae.
  
  ## Specie
  
  * Hydractinia aculeata
  * Hydractinia aggregata (Fraser, 1911)
  * Hydractinia allmani
  * Hydractinia altispina
  * Hydractinia americana (Edwards, 1972)
  * Hydractinia angusta
  * Hydractinia apicata
  * Hydractinia arctica
  * Hydractinia areolata
  * Hydractinia arge (Clarke, 1882)
  * Hydractinia armata (Fraser, 1940)
  * Hydractinia australis
  * Hydractinia bayeri
  * Hydractinia bella
  * Hydractinia betkensis
  * Hydractinia borealis
  * Hydractinia brachyurae
  * Hydractinia calderi
  * Hydractinia californica (Torrey, 1904)
  * Hydractinia canalifera
  * Hydractinia carcinicola
  * Hydractinia carica (Bergh, 1887)
  * Hydractinia carnea (M. Sars, 1846)
  * Hydractinia carolinae (Fraser, 1912)
  * Hydractinia claviformis
  * Hydractinia conchicola
  * Hydractinia cryptoconcha
  * Hydractinia cryptogonia
  * Hydractinia cytaciformis
  * Hydractinia dendritica
  * Hydractinia diogenes
  * Hydractinia disjuncta
  * Hydractinia dubia (Mayer, 1900)
  * Hydractinia echinata (Fleming, 1828)
  * Hydractinia epiconcha
  * Hydractinia epispongia
  * Hydractinia exigua
  * Hydractinia fucicola (M. Sars, 1846)
  * Hydractinia granulata
  * Hydractinia hancocki
  * Hydractinia hayamaensis
  * Hydractinia hooperii (Sigerfoos, 1899)
  * Hydractinia humilis
  * Hydractinia inabai
  * Hydractinia inermis
  * Hydractinia ingolfi
  * Hydractinia kaffaria
  * Hydractinia laevispina (Fraser, 1922)
  * Hydractinia longispina
  * Hydractinia mar
  * Hydractinia marsupialia
  * Hydractinia meteoris
  * Hydractinia milleri (Torrey, 1902)
  * Hydractinia minima (Trinci, 1903)
  * Hydractinia minoi
  * Hydractinia minuta (Mayer, 1900)
  * Hydractinia misakinensis
  * Hydractinia monocarpa (Allman, 1874)
  * Hydractinia monoon
  * Hydractinia multigranosi
  * Hydractinia multispina (Fraser, 1938)
  * Hydractinia multitentaculata
  * Hydractinia nassa
  * Hydractinia novaezelandiae
  * Hydractinia ocellata
  * Hydractinia otagoensis
  * Hydractinia pacifica
  * Hydractinia parvispina (Hartlaub, 1905)
  * Hydractinia paucispinata
  * Hydractinia piscicola
  * Hydractinia polycarpa (Fraser, 1938)
  * Hydractinia polyclina (L. Agassiz, 1862)
  * Hydractinia polystyla
  * Hydractinia proboscidea
  * Hydractinia prolifica (Fraser, 1948)
  * Hydractinia pruvoti
  * Hydractinia quadrigemina
  * Hydractinia reticulata
  * Hydractinia reticulata
  * Hydractinia rubricata
  * Hydractinia rugosa
  * Hydractinia sarsi
  * Hydractinia selena (Mills, 1976)
  * Hydractinia serrata
  * Hydractinia sodalis
  * Hydractinia spinipapillaris
  * Hydractinia spiralis
  * Hydractinia symbiolongicarpus (Buss & Yund, 1989)
  * Hydractinia symbiopollicaris (Buss & Yund, 1989)
  * Hydractinia tenuis
  * Hydractinia thatcheri
  * Hydractinia uchidai
  * Hydractinia uniformis
  * Hydractinia valens (Fraser, 1941)
  * Hydractinia vallini
  * Hydractinia yerii
  