Invasion History

First Non-native North American Tidal Record: 2003
First Non-native West Coast Tidal Record: 2003
First Non-native East/Gulf Coast Tidal Record:

General Invasion History:

Corella inflata was described from southern British Columbia (Huntsman 1912, cited by Lambert et al. 1981), but later considered conspecific with C. willmeriana by Van Name (1945). Lambert et al. (1981) compared and distinguished the two species, noting differences in range. Corella wilmeriana was known to range from Alaska to central California, while C. inflata was known only from southern British Columbia to Puget Sound. In recent surveys, it was found north to Prince William Sound (Hines and Ruiz 2000; Ruiz et al., unpublished data), and the Chukchi Sea, north of Alaska (USNM 1116525, US National Museum of Natural History 2012). Since 2003, it has been found in Coos Bay OR (Chang 2009; Onuma 2011), Humboldt Bay CA (Wilson 2011), and San Francisco Bay CA (Chang 2009; Ruiz et al., unpublished data; Steve Foss, personal communication). These southern occurrences are definite introductions, probably due to ship or boat fouling.

North American Invasion History:

Invasion History on the West Coast:

In 2003, Corella inflata appeared in Coos Bay, Oregon, but disappeared following heavy rains in 2006 (R. Emlet and J. T. Carlton, pers. comm., cited by Chang 2009). It reappeared later in Coos Bay, and settling larvae were photographed by Onuma (2011). Corella inflata was common in Humboldt Bay in 2009, during a study of fouling organisms (Wilson 2011), but was not found in 2011 samples (Gretchen Lambert, personal communication). In 2008, C. inflata was abundant in San Francisco Bay at San Francisco Marina and Sausalito Marine Harbor (Chang 2009), and in additional locations in a 2010 survey (Richardson Bay and St. Francis Yacht Harbor, Steve Foss, personal communication).


The solitary tunicate Corella inflata has an oblong-oval body, distorted by a greatly enlarged atrial chamber, giving it a roughly cubical outline. The test is more or less transparent or translucent. The oral and atrial apertures open at the same level at the anterior end, and have poorly developed siphons. The rectum, sperm duct, and oviduct are short, about half the body length, and end at the base of the expanded atrial chamber. In C. willmeriana, which has a very small atrial chamber, the rectum, sperm duct and oviduct extend the full body length to the atrial siphon. The eggs are spawned into the dorsal atrial chamber, and are brooded there in a floating mass due to their very large ammonium-filled follicle cells, until several hours after the tadpoles hatch. The filiform oral tentacles are in one row, and vary in number from 35 to 65, while those in C. willmeriana are sometimes in two or three rows, and range from 45 to 95. The oral musculature in C. inflata is weak, and the body is flaccid when removed from the tunic, while in C. willmeriana it is more developed, and often contracts in preservation, making it difficult to count the tentacles. Body length and width of C. inflata are about equal, reaching about 30 mm (Van Name 1945; Lambert et al. 1981).


Taxonomic Tree

Kingdom:   Animalia
Phylum:   Chordata
Subphylum:   Tunicata
Class:   Ascidiacea
Order:   Phlebobranchia
Family:   Corellidae
Genus:   Corella
Species:   inflata


Potentially Misidentified Species

Corella borealis
Arctic species (Van Name 1945)

Corella eumyota
Southern Hemisphere species, recently introduced to Europe

Corella willmeriana
Alaska to California (Van Name 1945; Abbot et al., in Carlton 2007)



A solitary tunicate is ovoid, elongate or vase-like in shape, with two openings or siphons. Most solitary tunicates attach to substrates by their side or base, but some attach with a conspicuous stalk. They are sessile filter feeders and have an oral and an atrial siphon. Water is pumped in through the oral siphon, where phytoplankton and detritus is filtered by the gills, and passed on mucus strings to the stomach and intestines. Waste is then expelled in the outgoing atrial water.

Solitary ascidians are hermaphroditic, meaning that both eggs and sperm are released to the atrial chamber. Eggs may be self-fertilized or fertilized by sperm from nearby animals, but many species have a partial block to self-fertilization. Depending on species, eggs may be externally or internally fertilized. In external fertilizers, eggs and sperm are released through the atrial siphon into the surrounding water column were fertilization takes place. In internal fertilizers, eggs are brooded and fertilized within the atrial chamber and then released into the water column upon hatching. Fertilized eggs hatch into a tadpole larva with a muscular tail, notochord, eyespots, and a set of adhesive papillae. The lecithotrophic (non-feeding, yolk-dependent) larva swims briefly before settlement. Swimming periods are usually less than a day and some larvae settle immediately after release, but the larval period can be longer at lower temperatures. Once settled, the tail is absorbed, the gill basket expands, and the tunicate begins to feed by filtering (Barnes 1983).


Phytoplankton, detritus

Trophic Status:

Suspension Feeder



General HabitatRockyNone
General HabitatMarinas & DocksNone
General HabitatGrass BedNone
Salinity RangePolyhaline18-30 PSU
Salinity RangeEuhaline30-40 PSU
Tidal RangeSubtidalNone
Vertical HabitatEpibenthicNone

Tolerances and Life History Parameters

Minimum Salinity (‰)20Chang et al. 2020
Maximum Height (mm)30Lambert and Lambert 1981
Broad Temperature RangeNoneCold-temperate
Broad Salinity RangeNonePoly-euhaline

General Impacts

There are no reported impacts for introduced populations of Corella inflata.

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
NEP-III Alaskan panhandle to N. of Puget Sound 0 Native Estab
NA-S1 None 0 Native Estab
P292 _CDA_P292 (San Juan Islands) 0 Native Estab
P290 Puget Sound 0 Native Estab
NEP-II Alaska south of the Aleutians to the Alaskan panhandle 0 Native Estab
NEP-IV Puget Sound to Northern California 2003 Def Estab
P170 Coos Bay 2004 Def Estab
P286 _CDA_P286 (Crescent-Hoko) 0 Native Estab
P293 _CDA_P293 (Strait of Georgia) 0 Native Estab
P130 Humboldt Bay 2009 Def Estab
NEP-V Northern California to Mid Channel Islands 2008 Def Estab
P090 San Francisco Bay 2008 Def Estab
P143 _CDA_P143 (Smith) 2010 Def Unk
P110 Tomales Bay 0 Def Unk

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude
767825 Ruiz et al., 2015 2011 2011-09-20 San Francisco Marina, San Francisco Bay, CA, California, USA Def 37.8067 -122.4432
768009 Ruiz et al., 2015 2012 2012-08-23 Sausalito Marine Harbor, San Francisco Bay, CA, California, USA Def 37.8609 -122.4853
768024 Ruiz et al., 2015 2012 2012-08-28 San Francisco Marina, San Francisco Bay, CA, California, USA Def 37.8071 -122.4341
768421 Ruiz et al., 2015 2013 2013-08-12 San Francisco Marina, San Francisco Bay, CA, California, USA Def 37.8078 -122.4354
768452 Ruiz et al., 2015 2013 2013-08-16 Sausalito Marine Harbor, San Francisco Bay, CA, California, USA Def 37.8611 -122.4851


Bingham, Brian L.; Reyns, Nathalie B. (1999) Ultraviolet radiation and distribution of the solitary ascidian Corella inflata (Huntsman), Biological Bulletin 196: 94-104

Carlton, James T. (Ed.) (2007) The Light and Smith Manual: Intertidal Invertebrates from Central California to Oregon Fourth Edition, Completely Revised and Expanded, University of California Press, Berkeley. Pp. <missing location>

Chang, Andrew Louis (2009) <missing title>, University of California at Davis, Davis CA. Pp. <missing location>

de Rivera, Catherine, and 27 authors (2005) Broad-scale non-indigenous species monitoring along the West Coast in National Marine Sanctuaries and National Estuarine Research Reserves report to National Fish and Wildlife Foundation, National Fish and Wildlife Foundation, Washington, D.C.. Pp. <missing location>

Green, Stephanie J. and 7 authors (2021) Broad-scale acoustic telemetry reveals long-distance movements and large home ranges for invasive lionfish on Atlantic coral reefs, Marine Ecology Progress Series 673: 117-134

Hines, Anson H.; Ruiz, Gregory M. (2000) Biological invasions of cold-water coastal ecosystems: ballast-mediated introductions in Port Valdez/Prince William Sound (Final Report), In: (Eds.) . , Valdez, Alaska. Pp. <missing location>

Lambert, Charles C.; Lambert, Ilsa M.; Lambert, Gretchen (1995) Brooding strategies in solitary ascidians: Corella species from north and south temperate waters, Canadian Journal of Zoology 73: 1666-1671

Lambert, Gretchen; Lambert, Charles C. (1981) Corella species in the American Pacific Northwest: distinction of C. inflata Huntsman from C. willmerinana Herdman 1898 (Ascidiacea, Phlebobranchia), Canadian Journal of Zoology 59: 1493-1504

Murray, Cathryn Clarke; Therriault, Thomas W.; Martone, Patrick T. (2012) Adapted for invasion? Comparing attachment, drag and dislodgment of native and nonindigenous hull fouling species, Biological Invasions <missing volume>: published online

Onuma, Megan 2011 Settling invertebrates of the Oregon Coast. <missing URL>

Simkanin, Christina; Fofonoff, Paul W.; Larson, Kriste; Lambert, Gretchen; Dijkstra, Jennifer A.; Ruiz, Gregory M. (2016) Spatial and temporal dynamics of ascidian invasions in the continental United States and Alaska, Marine Biology 163: Published online

U.S. National Museum of Natural History 2002-2021 Invertebrate Zoology Collections Database.

Van Name, Willard G. (1945) The North and South American ascidians, Bulletin of the American Museum of Natural History 84: 1-462

White, Laura F.; Orr, Lindsay C. (2011) Native clams facilitate invasive species in an eelgrass bed, Marine Ecology Progress Series 424: 87-95

Wilson, Emily Erin (2011) <missing title>, Humboldt State University, Eureka CA. Pp. <missing location>