Invasion History

First Non-native North American Tidal Record: 1927
First Non-native West Coast Tidal Record: 1927
First Non-native East/Gulf Coast Tidal Record: 2022

General Invasion History:

The encrusting bryozoan Schizoporella japonica was first described from Sagami Bay, Japan, as a variety of S. unicornis. It is native to the Northwest Pacific, from China to northern Japan (Dick et al. 2005). However, the extent of its native and introduced ranges is uncertain because of confusion with S. unicornis, S. errata, and other Schizoporella species.

North American Invasion History:

Invasion History on the West Coast:

In the Northeast Pacific, Schizoporella japonica has been introduced in many locations, from Alaska to Morro Bay, California, with Pacific Oysters (Crassostrea gigas) from Japan (Powell 1970; Dick et al. 2005). It was first collected on the US West Coast in Samish Bay, Puget Sound in 1927 (McCain and Ross 1974; Ross and McCain 1976, cited by Carlton 1979). Taxonomic uncertainties make it difficult to document the spread of this bryozoan. Powell (1970) reported that in 1969 it was found from central Vancouver Island to Puget Sound and Willapa Bay. It has been found in other coastal bays, including Grays Harbor, Washington (McCain and Ross 1974, cited by Carlton 1979), Coos Bay, Oregon (in 1986, Carlton 1989), and Humboldt Bay (in 1992, Barnhart et al. 1992, cited by Boyd et al. 2002), Fort Bragg Harbor (in 2001, Fairey et al. 2002), Bodega Harbor (Standing et al. 1975, cited by Carlton 1979), Tomales Bay (in 1947, Carlton 1979), Elkhorn Slough (Osburn 1952, cited by Carlton 1979), Monterey Bay (Haderlie 1971, cited by Carlton 1979), and Morro Bay, California (in 1964, Powell 1970). In San Francisco Bay, it was first collected from Berkeley Yacht Harbor (in 1963, Banta 1963, cited by Cohen and Carlton 1995), and it is now widespread in the central and south portions of the Bay (Cohen et al. 2005; Ruiz et al., unpublished data).

To the north, it has been found in Alaska, from Ketchikan (in 2001, Dick et al. 2005, Ruiz et al., 2006), Sitka (in 2001, Ruiz et al. 2006), and Valdez and Tatilek, Prince William Sound (in 1998, Hines and Ruiz 2000). The southern extent of its range is uncertain. Schizoporella on fouling plates from south of Point Conception (Los Angeles-San Diego) appear to represent a different species (Linda McCann, personal communication).

Invasion History Elsewhere in the World:

Introduced populations in Hawaii, Australia, and New Zealand, identified as Schizoporella unicornis, could represent S. japonica (Dick et al. 2005). Molecular and morphological studies will be needed to determine the identity of Schizoporella populations worldwide.

In February 2011, S. japonica was discovered in fouling communities in Holyhead, Wales. Subsequently, populations were found in the Orkney Islands on the east coast of Scotland, Portavadie on the west coast of Scotland (Ryland et al. 2014) and in the Shetland Islands (Collin et al. 2015). In June-July 2014, this bryozoan was found at Floro, Alesund, and Kristiansund, Norway (61-63 S, Porter et al. 2015).


Schizoporella japonica is a heavily calcified encrusting bryozoan, growing on rocks, shells, and algae. The colonies sometimes form a double layer, due to overgrowth of one colony over another and occasionally form leaf-like lobes free from the substrate. Colonies range in color from whitish pink to deep red and can grow up to 5 cm across. Its zooecia are roughly rectangular, arranged in columns radiating from a center, with distinct grooves at lateral walls. The width of the zooids increases along the column, until a bifurcation point is reached where the zooids are nearly as wide as long. After the bifurcation point, daughter zooids are again narrow and elongate. The frontal wall is somewhat convex, with areolar pores (in circular pits) around the margins, and small pseudopores (not in pits) covering the entire frontal surface. There is often a small umbo (knob) below the orifice. The orifice is broader than long, semicircular on the distal side, with the proximal side separated by a pair of blunt condyles, and forming a broad sinus. The zooecia lack spines and the avicularia may be single, paired, or absent on a zooid. The ovicells are globose, with scattered small pores, and resting on the frontal walls of zooids. They may have a calcified, rough surface and can be scattered among the zooids or form a reproductive band within the colony (description from Dick et al. 2005).

In California, S. japonica is bright orange in color, whereas the similar S. errata tends to be paler. The latter can have adventitious, large, frontal avicularia, though they may be rare. Schizoporella errata is rare on experimental fouling panels, but quite abundant in San Francisco Bay as bryoliths (unattached, living colony masses), whereas S. japonica is very abundant on panels, but has never been seen to form bryoliths (Linda McCann, personal communication 2009).


Taxonomic Tree

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


Schizoporella unicornis (Oka, 1929)
Schizoporella unicornis var. japonica (Ortmann, 1890)

Potentially Misidentified Species

Schizoporella errata
Several species of Schizoporella have been reported from California waters. One form appears to be the Northeast Atlantic warm-water form S. errata (Linda McCann, personal communication).

Schizoporella pseudoerrata
This very similar species was newly described is known from California fouling communities, but is not likely to be a native species and may be a redescription of a form of a previously described Schizoporella (James T. Carlton, personal communication, 2013). and is presumed to be native. See Soule et al. 2007) for a description.

Schizoporella sp.
One morphotype found in San Diego may be the species described by the Soules from Baja, Cal (Soule and Soule 1964), as S. occidentalae, but more specimens are necessary to confirm the identification (Linda McCann personal communication, 2013)

Schizoporella unicornis
Dick et al. (2005) have re-examined Schizoporella sp. from Ketchikan, Alaska, and both sides of the Pacific, and have raised Ortmann's S. unicornis var. japonica' to the status of a distinct species, noting differences between this form and British S. unicornis, and similarities between the Japanese type specimen and Alaskan Schizoporella, as well as specimens collected from Smithsonian Environmental Research Center fouling plates from Puget Sound to San Francisco.



Life History- Schizoporella japonica is an encrusting, calcified bryozoan composed of many individual zooids. The zooids feed by extending the ciliated tentacles of the lophophore as a funnel, creating a current, and driving food particles into their mouths. The food is guided along the tentacles and through the pharynx by the cilia. Larger food particles can be moved or captured by flicking or contracting the tentacles (Barnes 1983). Larvae of the congeneric S. errata are lecithotrophic, and have a short planktonic period (less than 1 day, Hayward and Ryland 1998). This is likely for S. japonica also. Larvae settle on a substrate and metamorphose into the first zooid of a colony, an ancestrula (Barnes 1983).

Ecology- Schizoporella japonica is known from oyster beds, pilings, shells, rocks, algae, and fouling plates (Powell 1970; Dick et al. 2005).



Trophic Status:

Suspension Feeder



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

Tolerances and Life History Parameters

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

General Impacts

Economic Impacts

spp. are common fouling organisms on ships' hulls, docks, and other hard surfaces (Woods Hole Oceanographic Institution 1952). Ryland (1971) suggests that the calcareous layers produced by the bryozoans may actually protect pilings and docks from borers. Powell (1970) considered that S. japonica (as S. unicornis) had little effect on live oysters, because the bryozoans settled primarily on dead shells and rocks, but were rarely seen on the living animals.

Ecological Impacts

Schizoporella spp. frequently dominate the fouling community on man-made structures and on rocks, shells, and algae (Ryland 1965; Powell 1970; Sutherland 1981; Hayward and McKinney 2002).

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
NWP-4b None 0 Native Estab
NWP-3b None 1882 Native Estab
NWP-4a None 0 Native Estab
NEP-I Alaska north of the Aleutians 1998 Def Estab
NEP-III Alaskan panhandle to N. of Puget Sound 1927 Def Estab
NWP-3a None 0 Native Estab
NEP-IV Puget Sound to Northern California 1970 Def Estab
NEP-V Northern California to Mid Channel Islands 1952 Def Estab
P292 _CDA_P292 (San Juan Islands) 1969 Def Estab
P297 _CDA_P297 (Strait of Georgia) 1974 Def Estab
P293 _CDA_P293 (Strait of Georgia) 1927 Def Estab
P290 Puget Sound 1943 Def Estab
P286 _CDA_P286 (Crescent-Hoko) 2002 Def Estab
P280 Grays Harbor 1974 Def Estab
P270 Willapa Bay 1970 Def Estab
P170 Coos Bay 1986 Def Estab
P130 Humboldt Bay 1992 Def Estab
P112 _CDA_P112 (Bodega Bay) 1975 Def Estab
P110 Tomales Bay 1952 Def Estab
P090 San Francisco Bay 1963 Def Estab
P080 Monterey Bay 1952 Def Estab
P070 Morro Bay 1964 Def Estab
NWP-2 None 0 Native Estab
P116 _CDA_P116 (Big Navaro-Garcia) 2001 Def Estab
P100 Drakes Estero 2006 Def Estab
NEA-II None 2011 Def Estab
NEA-III None 2012 Def Estab
AR-V None 2014 Def Estab
NEP-VI Pt. Conception to Southern Baja California 2015 Def Estab
P062 _CDA_P062 (Calleguas) 2015 Def Estab
P050 San Pedro Bay 2017 Def Estab
NA-S3 None 2022 Def Estab
NEA-V None 2015 Def Estab

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude
767321 Ruiz et al., 2015 2012 2012-08-13 Coast Guard, Bodega Bay, California, USA Def 38.3126 -123.0512
767328 Ruiz et al., 2015 2012 2012-08-14 Spud Point South, Bodega Bay, California, USA Def 38.3281 -123.0574
767334 Ruiz et al., 2015 2012 2012-08-14 Spud Point North, Bodega Bay, California, USA Def 38.3301 -123.0572
767344 Ruiz et al., 2015 2012 2012-08-21 Lucas/Tides, Bodega Bay, California, USA Def 38.3284 -123.0445
767351 Ruiz et al., 2015 2012 2012-08-21 Porto Bodega, Bodega Bay, California, USA Def 38.3333 -123.0525
767391 Ruiz et al., 2015 2012 2012-08-16 Tomales-SNPS, Bodega Bay, California, USA Def 38.1359 -122.8719
767405 Ruiz et al., 2015 2012 2012-08-17 Tomales- Shell Beach, Bodega Bay, California, USA Def 38.1163 -122.8713
767536 Ruiz et al., 2015 2013 2013-07-30 Hilton Resort Docks, Mission Bay, CA, California, USA Def 32.7791 -117.2128
767576 Ruiz et al., 2015 2013 2013-08-30 201 Main, Morro Bay, CA, California, USA Def 35.3564 -120.8474
767589 Ruiz et al., 2015 2013 2013-08-27 City Harbor, Morro Bay, CA, California, USA Def 35.3709 -120.8582
767601 Ruiz et al., 2015 2013 2013-09-05 Launch Ramp, Morro Bay, CA, California, USA Def 35.3577 -120.8508
767623 Ruiz et al., 2015 2013 2013-08-31 Morro Bay Marina, Morro Bay, CA, California, USA Def 35.3641 -120.8532
767641 Ruiz et al., 2015 2013 2013-09-03 State Park Marina, Morro Bay, CA, California, USA Def 35.3459 -120.8423
767653 Ruiz et al., 2015 2013 2013-09-04 Tidelands, Morro Bay, CA, California, USA Def 35.3602 -120.8521
767818 Ruiz et al., 2015 2011 2011-09-20 San Francisco Marina, San Francisco Bay, CA, California, USA Def 37.8067 -122.4432
767886 Ruiz et al., 2015 2011 2012-09-19 Sausalito Marine Harbor, San Francisco Bay, CA, California, USA Def 37.8609 -122.4853
767901 Ruiz et al., 2015 2011 2011-09-21 South Beach Harbor, San Francisco Bay, CA, California, USA Def 37.7797 -122.3871
767962 Ruiz et al., 2015 2011 2011-09-12 Corinthian Yacht Club, San Francisco Bay, CA, California, USA Def 37.8103 -122.3228
767999 Ruiz et al., 2015 2012 2012-08-23 Sausalito Marine Harbor, San Francisco Bay, CA, California, USA Def 37.8609 -122.4853
768016 Ruiz et al., 2015 2012 2012-08-28 San Francisco Marina, San Francisco Bay, CA, California, USA Def 37.8071 -122.4341
768031 Ruiz et al., 2015 2012 2012-08-27 Port of San Francisco Pier 31, San Francisco Bay, CA, California, USA Def 37.8078 -122.4060
768369 Ruiz et al., 2015 2013 2013-08-14 Redwood City Marina, San Francisco Bay, CA, California, USA Def 37.5024 -122.2134
768412 Ruiz et al., 2015 2013 2013-08-12 San Francisco Marina, San Francisco Bay, CA, California, USA Def 37.8078 -122.4354
768444 Ruiz et al., 2015 2013 2013-08-16 Sausalito Marine Harbor, San Francisco Bay, CA, California, USA Def 37.8611 -122.4851
778081 Working Group on Invasions and Transfers of Marine Organsims 1011 Magdalen Islands Def 47.4483 -61.7522


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