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Diazona violacea

Diazona violacea

Football sea-squirt

   Diazona violacea is a colonial ascidian forming massive colonies of up to 40 cm in diameter and 20 cm in height. Young colonies are rather ball-shaped, whereas older ones are slightly flattened. The zooids are joined in a common gelatinous cushion-shaped base. The branchial parts of the zooids (the upper parts) are distinct and emerge of 2 cm from the base. The test is more or less translucent, white or yellowish. A vertical line draws the endostyle of each zooid; the atrial and oral siphons are underlined by a white margin and six white spots ornate the upper part of the pharynx. Diazona zooids resemble clavelina ones but their bases are different: a thick basal mass for Diazona versus a thin basal stolon for Clavelina.
At the end of summer, after reproduction time, zooids atrophy and there's only the basal mass left. In spring-time, the colony buds again from this base.
It lives attached to rocks or stones covered by sand, in strong current-swept areas between 15 and 200 meters deep in the Atlantic Ocean, the English Channel and the Mediterranean Sea.

Classification

 (source : European Register of Marine Species)

  • Chordata [Phylum]
  • Tunicata [Subphylum]
  • Ascidiacea [Class]
  • Enterogona [Order]
  • Aplousobranchia [Suborder]
  • Diazonidae [Family]
  • Diazona violacea Savigny, 1816

Page glossary


Zooid : Individual, single animal.
Test : or tunic: thick layer secreted by the mantel containing cellulose and protecting the animal.
Oral siphon : Opening by which water is drawn in the ascidian.
Atrial siphon : Opening through which water is expelled.

Diazona violacea. Diazona violacea
Close view.

Diazona violacea. Diazona violacea
Juvenile.

Diazona violacea. Diazona violacea
Colony.

Authors


Top photograph :
© Javier Santiago. Published with author's kind permission : 
Diazona violacea, Ria de Arosa, Galice, North-West of Spain. Depth 32 meters.
Bottom photographs : © Javier Santiago. Published with author's kind permission : 
Diazona violacea, Close view.. Ria de Arose, Galicia, North-West Spain. Depth 32 meters.
© Wilfried Bay-Nouailhat. Published with author's kind permission : 
Diazona violacea, Juvenile.. Illes Medes, Costa Brava, East Spain. Depth 22 meters.
© Wilfried Bay-Nouailhat. Published with author's kind permission : 
Diazona violacea, Colony.. Baie de Lannion, North Brittany, West of France. Depth 28 meters.
Text :  Anne Bay-Nouailhat © 2007-2017.
Translation :  Anne Bay-Nouailhat © 2007-2017.

How to cite this page in publications


Bay-Nouailhat A., January 2007, Description of Diazona violacea, Available on line at http://www.european-marine-life.org/32/diazona-violacea.php, consulted on 24 October 2017.
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