Diazona violacea Savigny, 1816

Description

Diazona violacea s 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.

Distribution

Diazona violacea 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 : World Register of Marine Species

Biota (Superdomain)
Animalia (Kingdom)
Chordata (Phylum)
Tunicata (Subphylum)
Ascidiacea (Class)
Aplousobranchia (Order)
Diazonidae (Family)
Diazona (Genus)
Diazona violacea (Species)

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.

Authors

Text : Anne Bay-Nouailhat © 2007 - 2020.

Photos : © Javier Santiago, Wilfried Bay-Nouailhat. PPublished with their kind permission.
Websites and reference works : Consult bibliography

How to cite this page

Bay-Nouailhat A., January 2007, Description of Diazona violacea, [On line] http://european-marine-life.org/32/diazona-violacea.php, consulted on 2020 September 29.