Invasion History

First Non-native North American Tidal Record:
First Non-native West Coast Tidal Record:
First Non-native East/Gulf Coast Tidal Record:

General Invasion History:


North American Invasion History:


We are tentatively treating "Bowerbankia gracilis" as a single species of North Atlantic origin, native to both coasts, but introduced to other ocean regions. It was described from Point Judith RI in 1855 (Leidy 1855) and now appears to be fairly continuously distributed from Florida and Spain to Greenland. However, a trans-Atlantic invasion cannot be ruled out. Animals identified as "B. gracilis" over its wide present range could also represent members of a species complex. According to Winston (pers.comm.), Northeast Pacfic "B. gracilis" are probably a separate species (Winston, personal communication; Soule et al., in Carlton 2007)., and are excluded from our database.


Taxonomic Tree

Kingdom:   Animalia
Phylum:   Bryozoa
Class:   Gymnolaemata
Order:   Ctenostomata
Suborder:   Carnosa
Superfamily:   Vesicularioidea
Family:   Vesiculariidae
Genus:   Bowerbankia
Species:   gracilis


Bowerbankia caudata (Hincks, 1880)
Valkeria caudata (Hincks, 1877)
Vesicularia gracilis (Verrill and Smith, 1874)

Potentially Misidentified Species




Trophic Status:

Suspension Feeder



General HabitatGrass BedNone
General HabitatCoarse Woody DebrisNone
General HabitatOyster ReefNone
General HabitatMarinas & DocksNone
General HabitatRockyNone
General HabitatVessel HullNone
Tidal RangeSubtidalNone
Tidal RangeLow IntertidalNone
Vertical HabitatEpibenthicNone

Tolerances and Life History Parameters

Minimum Salinity (‰)10Field data, Chesapeake Bay (Osburn 1944)
Maximum Salinity (‰)35Field data, Mediterranean Sea lagoons (Occhipinti Ambrogi and d'Hondt 1981), but may tolerate higher salinites.

General Impacts

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
NA-ET3 Cape Cod to Cape Hatteras 1855 Native Estab
CAR-VII Cape Hatteras to Mid-East Florida 0 Native Estab
CAR-I Northern Yucatan, Gulf of Mexico, Florida Straits, to Middle Eastern Florida 0 Native Estab
NA-ET2 Bay of Fundy to Cape Cod 0 Native Estab
SA-II None 1941 Crypto Estab
SA-I None 1965 Crypto Estab
B-II None 1930 Native Estab
B-III None 0 Native Estab
B-IV None 0 Native Estab
B-V None 0 Native Estab
NEA-II None 0 Crypto Estab
NEA-IV None 0 Crypto Estab
MED-III None 0 Crypto Estab
NEA-V None 0 Crypto Estab
MED-VII None 0 Crypto Estab
MED-IX None 0 Crypto Estab
CIO-I None 1968 Def Estab
CIO-II None 1959 Def Estab
NWP-4a None 1969 Def Estab
AUS-VIII None 1974 Def Estab
AUS-VII None 0 Def Estab
AUS-VI None 0 Def Estab
AUS-X None 0 Def Estab
NZ-IV None 1965 Def Estab
MED-II None 0 Crypto Estab
NEA-III None 0 Crypto Estab
AR-IV None 0 Crypto Estab
NA-S2 None 0 Native Estab
NA-ET1 Gulf of St. Lawrence to Bay of Fundy 0 Native Estab
NA-S3 None 0 Native Estab
AR-V None 0 Crypto Estab
AR-III None 0 Crypto Estab
CAR-II None 0 Native Estab
CAR-IV None 0 Native Estab
MED-VI None 0 Crypto Estab
CAR-III None 1939 Native Estab

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude


Leidy, Joseph (1855) Contributions towards a knowledge of the marine invertebrate fauna, of the coasts of Rhode Island and New Jersey, Journal of the Academy of Natural Sciences of Philadelphia <missing volume>: 135-151

Maturo, Frank J. S., Jr. (1957) A study of the Bryozoa of Beaufort, North Carolina and vicinity, Journal of the Elisha Mitchell Scientific Society 72(1): 11-68

Osburn, Raymond C. (1944) A survey of the Bryozoa of Chesapeake Bay, Chesapeake Biological Laboratory Publications 63: 1-55

Waeschenbach, Andrea; Vieira, Leandro M.; Reverter-Gil, Oscar; Souto-Derungs, Javier; Nascimento, Karine B.; Fehlauer-Ale, Karin H. (2015) A phylogeny of Vesiculariidae (Bryozoa, Ctenostomata) supports synonymization of three genera and reveals possible cryptic diversity, Zoologica Scripta <missing volume>: <missing location>

Winston, Judith E. (1977) Distribution and ecology of estuarine ectoprocts: a critical review., Chesapeake Science 18(1): 34-57