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:


Encrusting bryozoan forming extensive white or pinkish one- or two layered sheets over rocks, docks, seaweed holdfasts, shells, etc. (West Coast colonies are reddish-orange to brown) Zooids rectangular or polygonal, convex, separated by deep grooves, typically 400-700 X 300-500 um. Primary orifice wider than long, with a deep V-shaped sinus occupying about 1/2 of its total width. Tiny teeth (condyles) at proximal inner corners of orifice. Frontal shield finely granular, densely perforated by small, round pores, and developing a stout, conical mound below the sinus. Avicularia single or paired, located beside the orifice. Polyp with 21-24 tentacles. Ovicells rest on the next (distal zooid), and are prominent, longer than wide, with an arched aperture, and grooves radiating around the center. Ancestrula oval with glassy frontal shield and 8 spines around orifice (Powell 1970; Hayward and Ryland 1999). Descripton Locations- Britsh Columbia, England.


Taxonomic Tree

Kingdom:   Animalia
Phylum:   Bryozoa
Class:   Gymnolaemata
Order:   Cheilostomata
Suborder:   Ascophora
Family:   Schizoporellidae
Genus:   Schizoporella
Species:   unicornis


Lepralia unicornis (Johnston, 1874 1996-06-13, None)
Schizoporella "unicornis" (sensu Powell, 1971)

Potentially Misidentified Species

Schizoporella errata

Schizoporella floridana

Schizoporella variabilis




Trophic Status:

Suspension Feeder



General HabitatCoarse Woody DebrisNone
General HabitatOyster ReefNone
General HabitatMarinas & DocksNone
General HabitatRockyNone
General HabitatCoral reefNone
General HabitatVessel HullNone
Salinity RangePolyhaline18-30 PSU
Salinity RangeEuhaline30-40 PSU
Tidal RangeSubtidalNone
Vertical HabitatEpibenthicNone

Tolerances and Life History Parameters

Broad Temperature RangeNoneCold temperate-Warm temperate
Broad Salinity RangeNonePolyhaline-Euhaline

General Impacts

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
NWP-4a None 0 Crypto Estab
NWP-3a None 0 Crypto Estab
NWP-2 None 0 Crypto Estab
SP-XXI None 1935 Crypto Estab
AUS-VIII None 0 Def Estab
AUS-X None 1953 Def Estab
AUS-VII None 1975 Def Estab
AUS-IV None 1953 Def Estab
AUS-XII None 1975 Def Estab
AUS-XIII None 1925 Def Estab
AUS-V None 0 Def Estab
NEA-II None 0 Native Estab
NEA-III None 0 Native Estab
AR-V None 0 Native Estab
NEA-IV None 0 Native Estab
NEA-V None 0 Native Estab
WA-I None 0 Native Estab
MED-I None 0 Native Estab
MED-II None 0 Native Estab
MED-VII None 0 Native Estab

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude


Carlton, James T. (1979) History, biogeography, and ecology of the introduced marine and estuarine invertebrates of the Pacific Coast of North America., Ph.D. dissertation, University of California, Davis. Pp. 1-904

Cohen, Andrew N.; Carlton, James T. (1995) Nonindigenous aquatic species in a United States estuary: a case study of the biological invasions of the San Francisco Bay and Delta, U.S. Fish and Wildlife Service and National Sea Grant College Program (Connecticut Sea Grant), Washington DC, Silver Spring MD.. Pp. <missing location>

Powell, N.A. (1970) Schizoporella unicornis - an alien bryozoan introduced into the Strait of Georgia., Journal of the Fisheries Research Board of Canada 27: 1847-1853

Tompsett, Scott; Porter, Joanne S.; Taylor, Paul D. (2009) Taxonomy of the fouling cheilostome bryozoans Schizoporella unicornis (Johnston) and Schizoporella errata (Waters), Journal of Natural History 43(35-36): 2227-2243