BIOTIC Species Information for Victorella pavida
Researched byMichelle Carter & Angus Jackson Data supplied byMarLIN
Refereed byThis information is not refereed.
Scientific nameVictorella pavida Common nameTrembling sea mat
MCS CodeY100 Recent SynonymsNone

PhylumBryozoa Subphylum
Superclass ClassGymnolaemata
Subclass OrderCtenostomatida
SuborderCarnosa FamilyVictorellidae
GenusVictorella Speciespavida

Additional InformationNo text entered
Taxonomy References Howson & Picton, 1997, Hayward, 1985, Gainey, 1997, Carter, 2004,
General Biology
Growth formMat
Feeding methodActive suspension feeder
Mobility/MovementPermanent attachment
Environmental positionEpifaunal
Typical food typesMicroalgae, rotifers. HabitAttached
BioturbatorNot relevant FlexibilityLow (10-45 degrees)
FragilityIntermediate SizeVery small(<1cm)
Height Growth Rate8 cm/month
Adult dispersal potentialNot researched DependencySee additional information
General Biology Additional Information

Environmental position
At Swanpool, the trembling sea mat can be found growing on any hard surfaces such as stones, traffic cones, and concrete structures but has a particular predilection for submerged stems and rhizomes of Phragmites australis.

Associated fauna
Several taxa are consistently present living amongst Victorella pavida colonies, and on the Phragmites reeds, forming a community of aquatic organisms collectively termed 'Aufwuchs'. Taxa typically present include: chironomid larvae, nematodes, protozoans Stentor spp., and Zoothamnium spp., green and brown algae, mites, Nais spp., freshwater bryozoan Plumatella repens, and various small freshwater crustaceans including Gammarus chevreuxi.

Growth rate
Approximately 8 cm of linear growth over 1 month was observed in cultured colonies of Victorella pavida (Carter, 2004).

Biology References Carter, 2004, Evans et al., 2003,
Distribution and Habitat
Distribution in Britain & IrelandIn the British Isles, Victorella pavida is only found in Swanpool: a brackish water lagoon near Falmouth in Cornwall.
Global distributionVarious sites on the southern shores of the North Sea on the European Mainland. Common in the Mediterranean. Also reported from India, the Black Sea, the Baltic, Brazil, the eastern United States and Japan.
Biogeographic rangeNot researched Depth range5m
MigratoryNot relevant   
Distribution Additional Information

The salinity of Swanpool is highly variable (0.5-22 psu) (Carter, 2004). A culvert connects the lagoon to the sea, with the incursion of seawater occurring on very high tides such as spring tides. At the northern end of Swanpool, the lagoon is fed freshwater from the Tregoniggie stream as well as diffuse drainage from a local catchment (Gainey, 1997; Evans, 2003).

Victorella pavida can grow on any hard surface and in Swanpool can be found growing on concrete surfaces, stones, traffic cones and mainly %Phragmites australis%.

Substratum preferencesArtificial (e.g. metal/wood/concrete)
Other species (see additional information)
Physiographic preferencesIsolated saline water (Lagoon)
Biological zoneLagoonal
Wave exposureNot relevant
Tidal stream strength/Water flowInsufficient information
SalinitySee additional Information
Habitat Preferences Additional Information
Distribution References Hayward, 1985, Carter, 2004, Dorey et al., 1973,
Reproduction/Life History
Reproductive typeProtandrous hermaphrodite
Developmental mechanismLecithotrophic
Reproductive SeasonJune to September Reproductive Location
Reproductive frequency Regeneration potential No
Life spanSee additional information Age at reproductive maturity<1 year
Generation time<1 year FecundityCa 25 eggs per gravid zooid
Egg/propagule size Fertilization type
Larval/Juvenile dispersal potentialInsufficient information Larval settlement period
Duration of larval stage<1 day   
Reproduction Preferences Additional Information
Life span
The life span of an individual zooid has not been researched in this species. Generally, the polypides (combined lophophore and gut) of individual zooids within a bryozoan colony have the potential to undergo a cyclical degeneration and regeneration process. Polypides may last for one week up to 10 weeks (Reed, 1991). With respect to the life span of a Victorella pavida colony, new colonies emerge from dormancy during the spring and when temperatures are approximately 13°C. By November and the onset of winter, zooids begin to degenerate and eventually only the asexually produced dormant resting bodies (hibernacula) remain. The hibernacula germinate again in the spring and the cycle begins again (Carter, 2004).

Reproduction frequency
Reproduction is seasonal and eggs were observed in zooids from June to September. Following reproduction the colony will degenerate in preparation for winter dormancy (Carter, 2004).

Approximately 25 eggs can be produced per gravid zooid (Carter, 2004). Overall colony fecundity, therefore, varies with size of the colony.
Reproduction References Reed, 1991, Carter, 2004,
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