BIOTIC Species Information for Botryllus schlosseri
Researched byLizzie Tyler Data supplied byUniversity of Sheffield
Refereed byThis information is not refereed.
Scientific nameBotryllus schlosseri Common nameStar ascidian
MCS CodeZD126 Recent SynonymsNone

PhylumChordata SubphylumTunicata
Superclass ClassAscidiacea
Subclass OrderPleurogona
SuborderStolidobranchiata FamilyStyelidae
GenusBotryllus Speciesschlosseri

Additional InformationNo text entered
Taxonomy References Berril, 1950,
General Biology
Growth formCushion
Crustose soft
Feeding methodPassive suspension feeder
Active suspension feeder
Mobility/MovementPermanent attachment
Environmental positionEpifaunal
Typical food typesSuspended particulates. HabitAttached
BioturbatorNot relevant FlexibilityHigh (>45 degrees)
FragilityIntermediate SizeMedium(11-20 cm)
Height Growth RateInsufficient information
Adult dispersal potential100-1000m DependencyIndependent
General Biology Additional InformationColonies that encrust algae may completely cover their substratum and appear pendant-like. Provides a source of food for cowries (Trivia spp.).
Biology References Chadwick-Furman & Weissman, 1995, Berril, 1950,
Distribution and Habitat
Distribution in Britain & IrelandFound all around Britain and Ireland
Global distributionPresent from the Faeroe Islands and west and south Norway to the Mediterranean including the Adriatic and Black Seas. Also present in the western Atlantic from Maine to New Jersey and in Florida.
Biogeographic rangeNot researched Depth range
MigratoryNon-migratory / Resident   
Distribution Additional InformationPopulations in the western Atlantic may have arrived on shipping and it is likely that, as a fast-growing fouling organism, Botryllus schlosseri may spread readily to other parts of the world.

Substratum preferencesBedrock
Large to very large boulders
Small boulders
Physiographic preferencesOpen coast
Strait / sound
Ria / Voe
Biological zoneLower Eulittoral
Sublittoral Fringe
Upper Infralittoral
Lower Infralittoral
Upper Circalittoral
Wave exposureModerately Exposed
Very Exposed
Very Sheltered
Tidal stream strength/Water flowVery Strong (>6 kn)
Strong (3-6 kn)
Moderately Strong (1-3 kn)
Weak (<1 kn)
Very Weak (negligible)
SalinityFull (30-40 psu)
Variable (18-40 psu)
Habitat Preferences Additional Information
Distribution References Berril, 1950, Hayward & Ryland, 1990,
Reproduction/Life History
Reproductive typeFission
Permanent hermaphrodite
Developmental mechanismLecithotrophic
Reproductive SeasonInsufficient information Reproductive LocationAs adult
Reproductive frequency Regeneration potential No
Life span1 year Age at reproductive maturity<1 year
Generation time<1 year Fecundity8
Egg/propagule size Fertilization typeSelf-fertile
Larval/Juvenile dispersal potential1km-10km Larval settlement period
Duration of larval stage<1 day   
Reproduction Preferences Additional InformationUp to eight eggs are produced per zooid. After fertilization and development to a tadpole stage, the tadpole is released and is free swimming for up to 36 hours (Berrill 1950; Berrill, 1975).
Reproduction References Chadwick-Furman & Weissman, 1995, Berril, 1950, Berril, 1975, Eckert, 2003,
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