Victorella pavida (Savilli Kent 1870)

Verder in Nederlands
Nederlands

  1. More information
  2. Photos
  3. Microscope photos and videos
  4. Hybernacula

Proposal for common name: Brackish-water bryozoan or moss animal

Victorella pavida

Photo made by Marco Faasse.

Classification

Class Family Genus Species First described by
Gymnolaemata Ctenostomata Victorella V. pavida Savilli Kent 1870

Synonyms

The following synonyms have been used to indicate Victorella pavida:

  1. Victorella pavida
  2. Victorella symbiotica

Description

Also see the generic class and genus description in the classification page.
A combination of literature has been used to create this description. The ecological part is largely based on [Brattström].

General Exclusively in (light) brackish water
The stolons make it also easy to differentiate from (other) freshwater species
The stolon crawls across the substrate and the zooids stick out from the stolon
Is rather variable in form
Color Whitish
Tentacle crown Round with 8 tentacles.
Size One zoöid is ?? long
A colony maximum ?? cm in diameter
Statoblasts None
Survives adverse conditions through hybernacula
Conditions In brackish water between 1 0/00 and 27 0/00 salinity
Can survive significant and rapid changes in salinity between these borders
Most likely grows only above 16° C; can handle significant temperature changes
Survives low temperatures to 0° C through hybernacula
Can survive temporary dry-fall (above ebb-line) (one observation)
Can handle polluted (eutrophic) water well
Largely found to limited depths (< 2 meter)
Often on ship docks, in harbors, on weed beds, on reeds as well as on a variety of other substrates
Distribution In The Nederlands found in a few locations in the Zeeland province, around Amsterdam and in at least one location in the Friesland province
Outside the Netherlands in large parts of the world
Additional
  1. V. pavida is 'livebearling' in the sense that the embryos develop in the coelom before hatching
  2. As V. pavida is found near sluices and in rivermouths, V. pavida must also be able to handle significant pH changes of at least 1º pH, as this is a likely pH difference between freshwater and seawater.

Relevant literature

  1. [Ambrogi] - Distribution of bryozoans in backish water of Italy
  2. [Braem V] - Über Victorella
  3. [Brattstrom] - Notes on Victorella pavida KENT
  4. [Luther] - Über das Vorkommen der Bryozoe Victorella pavida im Finnischen Meerbusen
  5. [Mundy] - A key to the British and European Freshwater Bryozoans
  6. [Wood II] - A new key to the freshwater bryozoans of Britain, Ireland and Continental Europe

My observations

  1. I have found V. pavida in the summer of 2005, thanks to information from Marco Faasse, in a pond south of the Goesse Meer on reeds. As the sight depth in the pond was about 5 cm, it was impossible to make photos.
  2. V. pavida grew on a reed stem and was, in a glass and with a magnifying glass, easily recognizable
  3. Marco told me he always finds V. pavida in a comparable environment: brackish water and an eutrophic situation (very limited sight-depth)
  4. Since then i have been back a few times and each time easily found V. pavida on an old reed.
  5. Under a microscope the stolons are not easily found. It is clear from my observation that many zooids are single and some may be connected by a stolon.
  6. I found several zooids growing on other zooids. It is unclear wether this is due to asexual reproduction by budding (similar to Hydra sp.) or maybe a larvae has settled on a nearby zooid and grown from there.