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Gymnangium montagui

Gymnangium montagui

Golden sea fern

   Gymnangium montagui is a hydroid that develops in erect feather-like colonies from 8 to 10 cm high and covering areas of about 10 cm2. Colonies bud from a basal stolon and grow in the same direction, parallel to each other. The outline of each plume is regular up to the 4/5th of their height, then it ends in an angular way. The main stem, called hydrocaulus, has from 100 to 300 alternate branches in two rows which are parallel and slightly curved. The tiny polyps, invisible to the eyes, are aligned on the curved side of the branches. Their tentacles open out on both sides of the inter-branches. The golden sea fern lives in moderatly current-swept areas between 10 and 40 meters deep, generally attached to the horizontal side of rocks, and protected by overhangs in shallow waters.
It is reported in the North-West Atlantic Ocean and is rare in the English Channel.


 (source : European Register of Marine Species)

  • Cnidaria [Phylum]
  • Hydrozoa [Class]
  • Hydroidolina [Subclass]
  • Leptothecata [Order]
  • Conica [Suborder]
  • Aglaopheniidae [Family]
  • Gymnangium montagui (Billard, 1912)

Page glossary

Budding : Asexual reproduction forming a new individual.
Basal stolon : Linear base linking colonies together and from where the colonies bud and grow.
Hydrocaulus : Main stem of a hydroid colony.
Polyp : Individual of a colony.

Gymnangium montagui. Gymnangium montagui
Golden sea fern.



Top photograph :
© Wilfried Bay-Nouailhat. Published with author's kind permission :
Gymnangium montagui, Anse de Camaret, West-Brittany, west of France. Depth 27 meters.
Bottom photograph : © Wilfried Bay-Nouailhat. Published with author's kind permission : 
Gymnangium montagui, Golden sea fern.. Iles Glénan, South-Brittany, West of France. Depth 14 meters.
Text :  Wilfried Bay-Nouailhat © 2007-2020.
Translation :  Anne Bay-Nouailhat © 2007-2020.

How to cite this page in publications

Bay-Nouailhat W., September 2007, Description of Gymnangium montagui, Available on line at http://www.european-marine-life.org/05/gymnangium-montagui.php, consulted on 10 July 2020.
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