Invasion History

First Non-native North American Tidal Record: 1940
First Non-native West Coast Tidal Record: 1940
First Non-native East/Gulf Coast Tidal Record:

General Invasion History:

The sea anemone Diadumene franciscana is known only from the California coast and Hawaii, but is believed to be introduced to both regions (Hand 1956; Carlton 1979; Carlton and Eldredge 2009). Its area of origin is unknown. It was first described from San Francisco Bay, California by Hand (1956), although it was originally collected around 1940 (Light 1941, cited by Carlton 1979). It has been regarded as a probable introduction because of the lack of previous records, its preference for settling on pilings and floats, and within warm embayments, including those with thermal effluents (Carlton 1979; Cohen and Carlton 1995). Since this species, or a similar form, has not been described from Japan, where the anemone fauna is well-studied, an Indo-Pacific or Southwest Pacific origin and transport by shipping or ballast water seems more probable than an introduction with Japanese oysters (Carlton 1979; Cohen and Carlton 1995).

North American Invasion History:

Invasion History on the West Coast:

Diadumene franciscana was first collected in San Francisco Bay, California in 1940 at Fruitvale Bridge in Oakland Harbor (Hand 1956), but is now widespread in ports and marinas throughout the bay, occurring in San Pablo Bay (Port San Pablo), South San Francisco Bay (San Leandro Marina, Pete's Harbor), and the Presidio Yacht Club, near the Golden Gate (Cohen 2005). It first appeared outside San Francisco Bay, in Morro Bay in 1973, where it was found in power plant effluents (Carlton 1979). In 1977, it was found in Mission Bay, San Diego (Dygert 1981, cited by Cohen and Carlton 1995). In 2000, Cohen et al. (2002) found it in several southern California locations, including the Agua Hedionda Lagoon, Los Angeles-Long Beach Harbor, Marina del Rey (Venice), and Channel Islands Harbor (near Oxnard). In 1995, it was collected in Tomales Bay (Cohen and Carlton 1995), and in 1998 it was found in Elkhorn Slough (Wasson et al. 2001). It is likely that most of these records outside San Francisco Bay represent transport by coastal shipping and boating, rather than invasions from the original source region.

Invasion History in Hawaii:

In 1998, D. franciscana was collected in Ala Wai Yacht Harbor in Honolulu, Oahu (Coles et al. 1999a). It has also been found on the south shore of Kaneohe Bay, Oahu (Carlton and Eldredge 2009).


When extended, the column of the Diadumene franciscana polyp is about 2x the width. Most specimens are less than 20 mm tall and 10 mm in diameter. This anemone has acontia, threadlike structures lined with cnidocytes (cells bearing nematocysts) which extend from the middle lobes of incomplete mesenteries, which partially divide the gastrovascular cavity. The acontia can be extended into the body cavity, or extruded through pores, as a defense in response to disturbance or handling. There are fewer than 100 tentacles, and there is a substantial tentacle-free zone around the mouth. The two tentacles (called directive tentacles) at each end of the slot like mouth are closer to the mouth than the other tentacles and are yellowish in color. This anemone is transparent when extended, but cream, gray, or light green when contracted. It is usually marked with longitudinal single or double white stripes, but can be unmarked. This anemone often occurs in clusters, because of the frequency of asexual reproduction (description from: Hand 1956; Cohen 2005; Fautin, in Carlton 2007).


Taxonomic Tree

Kingdom:   Animalia
Phylum:   Cnidaria
Class:   Anthozoa
Subclass:   Zoantharia
Order:   Actiniaria
Suborder:   Thenaria
Family:   Diadumenidae
Genus:   Diadumene
Species:   franciscana


Potentially Misidentified Species

Diadumene leucolena
This East Coast anemone has pink or salmon-colored tentacles, though the column may be almost white. The column is long and slender, when extended (Cohen 2005; Fautin, in Carlton 2007).

Diadumene lighti
This native anemone lives on the open coast, among algal holdfast, and usually has bulges and kinks in its column (Cohen 2005; Fautin, in Carlton 2007).

Diadumene lineata
This northwest Pacific anemone has a stout column, which is highly variable in color, but most frequently brown with green and orange vertical stripes, and white tentacles.

Diadumene sp. 1
This anemone, of unknown origin, lacks distinctive directive tentacles, and is usually light orange or yellow.



Sea anemones of the genus Diadumene can reproduce sexually by releasing eggs and sperm into the water, and asexually by longitudinal fission, or by a method called pedal laceration. It is not known whether Diadumene franciscana reproduces sexually in California. Another introduced anemone, D. lineata, apparently reproduces primarily asexually in its introduced range (Shick et al. 1979; Ting and Geller 2000). In pedal laceration, as the anemone moves, a portion of its base is left behind, and grows into a new anemone (Barnes 1983). Its frequent occurrence in colonies of up to 200 individuals suggests asexual reproduction. However, to our knowledge, there have been no studies of the modes of reproduction in D. franciscana.

This anemone is known from estuaries and sheltered waters, where it grows on pilings, floats, and seaweeds (Carlton 1979; Cohen and Carlton 1995; Cohen 2005). Like other anemones, it feeds by trapping zooplankton and small epibenthic animals on its tentacles (Barnes 1983).


Zooplankton, small epibenthos

Trophic Status:




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

Tolerances and Life History Parameters

Broad Temperature RangeNoneCold temperate-Subtropical
Broad Salinity RangeNonePolyhaline-Euhaline

General Impacts

No impacts have been reported for Diadumene franciscana.

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
NEP-V Northern California to Mid Channel Islands 1940 Def Estab
NEP-VI Pt. Conception to Southern Baja California 1977 Def Estab
SP-XXI None 1998 Def Estab
P070 Morro Bay 1973 Def Estab
P080 Monterey Bay 1998 Def Estab
P090 San Francisco Bay 1940 Def Estab
P110 Tomales Bay 1995 Def Estab
P030 Mission Bay 1977 Def Estab
P023 _CDA_P023 (San Louis Rey-Escondido) 2000 Def Estab
P050 San Pedro Bay 2000 Def Estab
P060 Santa Monica Bay 2000 Def Estab
P062 _CDA_P062 (Calleguas) 2000 Def Estab
P093 _CDA_P093 (San Pablo Bay) 1940 Def Estab

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude


Barnes, Robert D. (1983) Invertebrate Zoology, Saunders, Philadelphia. Pp. 883

California Academy of Sciences 2005-2015 Invertebrate Zoology Collection Database. <missing URL>

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

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>

Carlton, James T.; Eldredge, Lucius (2009) Marine bioinvasions of Hawaii: The introduced and cryptogenic marine and estuarine animals and plants of the Hawaiian archipelago., Bishop Museum Bulletin in Cultural and Environmental Studies 4: 1-202

Cohen, Andrew N. 2005-2024 Exotics Guide- Non-native species of the North American Pacific Coat.

Cohen, Andrew N. and 12 authors (2002) Project report for the Southern California exotics expedition 2000: a rapid assessment survey of exotic species in sheltered coastal waters., In: (Eds.) . , Sacramento CA. Pp. 1-23

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>

Coles S. L., DeFelice R. C., Eldredge, L. G. (1999a) Nonindigenous marine species introductions in the harbors of the south and west shores of Oahu, Hawaii., Bishop Museum Technical Report 15: 1-212

Fautin, Daphne G.; Hand, Cadet (2007) <missing title>, University of California, Berkeley. Pp. 173-184

Gimenez, Lucas H.; Brante, Antonio (2021) Do non-native sea anemones (Cnidaria: Actiniaria) share a common invasion pattern? – A systematic review, Aquatic Invasions 16: 365-390

Glon, Heather; Daly, Marymega; Carlton, . James, T.; Flenniken, Megan M.; Currimjee, Zara (2020) Mediators of invasions in the sea: life history strategies; and dispersal vectors facilitating global sea anemone introductions, Biological Invasions 22: pages3195–3222

Hand, Cadet (1955) The sea anemones of central California. Part III: The Acontiarian anemones., The Wasmann Journal of Biology 13(2): 189-251

Shick, J. Malcolm; Hoffman, Richard J.; Lamb, Allen N. (1979) Asexual reproduction, population structure, and genotype-environment interactions in sea anemones., American Zoologist 19: 699-713

Ting, Joy H.; Geller, Jonathan B. (2000) Clonal diversity in introduced populations of an Asian sea anemone in North America, Biological Invasions 2: 23-32

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

Wasson, Kerstin; Zabin, C. J.; Bedinger, L.; Diaz, M. C.; Pearse J. S. (2001) Biological invasions of estuaries without international shipping: the importance of intraregional transport, Biological Conservation 102: 143-153