Virgularia mirabilis is a sea pen of up to 60 cm tall. Its leaf-like tiny branches
tappering at the bottom and the top of the colony give it a delicate feather-shape. Generally, the
internal calcareous axis is visible at the upper end of the sea pen. Embedded in mud, the long stalk reaches
the half of the whole length of the colony. In the upper part, the rachis bears polyps in leaf-like
series of 5 to 12 autozooids on each side of the straight central axis. Siphonozooids, in an oblique row
at the base of each "leaf", are not much visible. Colonies vary from white to yellow and can luminesce in darkness.
When disturbed,
colonies may quickly and entirely withdraw in the substratum.
Virgularia mirabilis is found in sheltered areas with soft bottoms such as fine sand or mud, from 10
meters down to 400 meters deep, in the North-East Atlantic Ocean, the
English Channel, the North Sea and the Mediterranean Sea, and also in the North-West Altantic along the
North-American coasts.
(source : European Register of Marine Species)
Colony : Group of several individuals of the same species. There, the colony has several individuals,
the polyps, but the whole colony is considered as the animal.
Polyps : Within these colonial animals, the polyp is the individual.
Rachis : Upper part of the Pennatulacea bearing polyps.
Autozooids : Specialized polyps in charge of catching food.
Siphonozooids : Specialized polyps without tentacles in charge of driving water into the colony.
Top photograph :
© Mat Vestjens. Published with author's kind permission :
Virgularia mirabilis,
Oban, West Highlands, West Scotland. Depth 16 meters.
Text : Wilfried Bay-Nouailhat © 2008-2010.
Translation : Anne Bay-Nouailhat © 2008-2010.
