Diadumene lineata
Family: Diadumenidae
Common names: Orange Striped Green Anemone,  more...
Synonyms: Aiptasiomorpha luciae Verrill 1898,  more...
Diadumene lineata image
Diadumene lineata  

Species Description: The striped anemone, Diadumene lineata, is a small, greenish anemone with white or orange stripes and usually 50-60 (and as many as 100) fully retractile, transparent or slightly colored tentacles. The body is smooth and cylindrical (Eldredge and Smith 2001).

A number of distinct morphs of this species, based on body color and stripe pattern were identified several decades ago, although these may actually represent points along a gradient in appearance (Uchida 1932, Shick and Lamb 1977).

Potentially Misidentified Species: Diadumene lineata may be potentially confused with other co-occurring anemones in the IRL, such as the pale anemone (Aiptasia pallida) and the warty anemone (Bunodosoma cavernata). The body of A. pallida is pale to brownish, more slender than that of H. lineata and lacking vertical stripes, possesses about half as many tentacles, and often irregular has pale rings around the tentacles. The tissues of A. pallida also typically harbor symbiotic photosynthetic zooxanthellae, discernable via microscopic examination. B. cavernata is typically brownish green with pale bluish columnar dots (warts) on its body.

Regional Occurrence: Diadumene lineata occurs intertidally to subtidally on solid substrata in protected areas.

This U.S. non-native, presumed to have come from a native range encompassing the Pacific Coast of Asia, now occupies suitable marine habitats throughout the northern hemisphere. Introduced populations are known to occur in the British Isles and in Western Europe, in the Mediterranean Sea, and on both coasts of North America (Barnes 1994, Cohen 2005). On the U.S. east coast, the species can be found in Maine and from Massachusetts to Florida. (Shick and Lamb 1977). H. lineata has also been previously collected in Texas and from the Suez Canal but appears not to have become established in these locations (Cohen 2005).

IRL Distribution: Diadumene lineata is likely to occur throughout the IRL basins where hard fouling surfaces such as rocks, pier pilings, boat hulls, mangrove roots, and oyster shells are available.

Age, Size, Lifespan: Diadumene lineata is a small anemone, typically less than 4 cm in height and with a tentacular crown of around the same size (Eldredge and Smith 2001).

Abundance: Localized Diadumene lineata populations are often ephemeral as well as irruptive, suddenly appearing in sizeable numbers and then after a time disappearing just as abruptly (Shick and Lamb 1977).

Reproduction: Like other anemones, Diadumene lineata can reproduce asexually or sexually (Slick 1991, Cohen 2005). Asexual propagation may be by means of longitudinal fission (splitting in half along a vertical plane) or through pedal laceration (pulling away from its point of attachment and leaving bits of tissue to be regenerated). Sexual reproduction occurs through the release of gametes into the water column and subsequent external fertilization (Shick and Lamb 1977). Carlton (1979) indicates that sexual reproduction occurs only infrequently outside of this species' native range.

Embryology: Embryonic development in Diadumene lineata occurs via a free-living planktonic stage persisting in the water column for an unknown duration.

Temperature: Diadumene lineata is broadly eurythermal, as evidenced both by its latitudinal range and by its ability to survive intertidal exposure to extreme summer and winter temperatures in parts of its range (Shick and Lamb 1977).

Different localized populations within the broader regional landscape exhibit very different and locally adaptive responses to extreme temperatures. For example, at 10°C H. lineata populations in Virginia exhibit reduced metabolic activity and protect themselves through encystment in mucus whereas cold-adapted Maine populations remain metabolically active at 0°C and below (Sassaman and Magnum 1970, Shick 1976).

H. lineata in San Francisco Bay experience annual temperatures between 14-24°C (Cohen 2005).

Salinity: The intertidal Diadumene lineata is euryhaline, able to cope with large salinity reductions when they occur [see references in Shick and Lamb 1977]. San Francisco Bay populations typically experience salinities ranging from 18-34 ppt. Individuals from these populations may succumb to prolonged exposure to lethal salinities below 12 ppt.

Desiccation: Intertidally located Diadumene lineata can retract their tentacles and contract into globular hemispheres to minimize exposure and possible desiccation. Encystment in mucus may also be employed during periods of prolonged exposure, and this trait may enhance the ability of the species to survive long-distance accidental transport (Cohen 2005).

Trophic Mode: Diadumene lineata is a carnivore that preys largely on water column protists and small crustaceans and other invertebrates (Bumann 1995).

Associated Species: None reported.

Invasion History: Unlike many past marine introductions, the historic spread of H. lineata to U.S. waters is well chronicled with the earliest biogeographic records dating to New Haven, Connecticut in 1892. Carlton (1979) indicates that this western Pacific (Japan, China, and Hong Kong) native was also present on the Pacific coast of North America within a decade of its arrival on the east coast.

Human-mediated dispersal modes historically contributing to the spread of the species include attachment to ship hulls and accidental inclusion in commercial shipments of oysters and seaweed (Shick and Lamb 1977, Gollasch and Riemann-Zurneck 1996, Cohen 2005). Hull fouling from Japan is the likely source of the initial east coast introduction while oyster shipments (Crassostrea virginica) from the Atlantic states to California likely led to introduction within San Francisco Bay. Hull fouling from New England probably led to introduction of H. lineata in Great Britain which had been confirmed by 1896.

Physiological tolerance with regard to several abiotic factors (see above), combined with the ability to propagate asexually are likely key reasons for the success of H. lineata as an invasive species (Gollasch and Riemann-Zurneck 1996).

Potential to Compete With Natives: Competitive interactions between introduced Diadumene lineata and native species have not been studied, but are presumed to be minimal.

Possible Economic Consequences of Invasion: The economic impacts of H. lineata introduction have not been studied, but are presumed to be minimal.

Barnes R.S.K. 1994. The brackish-water fauna of northwestern Europe. Cambridge, Cambridge University Press.

Bumann D. 1995. Localization of Digestion Activities in the Sea Anemone Haliplanella luciae. Biological Bulletin 189: 236-237.

Carlton J.T. 1979. History, biogeography, and ecology of the introduced marine and estuarine invertebrates of the Pacific coast of North America. Unpublished Ph.D. Dissertation, University of California, Davis. 904 pp.

Cohen A.N. 2005 Guide to the Exotic Species of San Francisco Bay. San Francisco Estuary Institute, Oakland, CA. Available online at exoticsguide.org.

Dunn F.D. 1982. Sexual reproduction of two intertidal sea anemones (Colenerata: Actiniaria) in Malaysia. Biotropica 14:262-271.

Eldredge L.G. and C.M. Smith. 2001. A guidebook of introduced marine species in Hawaii. Bishop Museum Technical Report 21.

Gollasch, S. and K. Riemann-Zurneck. 1996. Transoceanic dispersal of benthic macrofauna: Diadumene lineata (Verrill, 1898) (Anthozoa, Actinaria) found on a ship's hull in a ship yard dock in Hamburg Harbour, Germany. Helgolander Meeresuntersuchungen, 50:253-258.

Shick J.M. and A.N. Lamb. 1977. Asexual Reproduction and Genetic Population Structure in the Colonizing Sea Anemone Haliplanella luciae. Biological Bulletin 153:604-617.

Sassaman and Magnum 1970. Patterns of temperature adaptation in North American coastal actinians. Marine Biology 7:123-130.

Slick J.M. 1991. A functional biology of sea anemones. Chapman and Hall, London.

Acrorhagi: Plural of Acrorhagus.

Acrorhagus: Cnidocyte-covered elevation on specialized sweeper tentacles or on the column of anthozoans.

Cnida: An eversible cnidarian organelle that occurs in the cnidocyte.

Cnidae: Plural of cnida.

Cnidocil: A short, stiff, bristle-like cilium that is borne on the cnidocyte and acts as a trigger for the cnida or nematocysts.

Coelenteron: The body cavity and gut of cnidarians and ctenophores; gastrovascular cavity.

Column: The stalk portion of sea anemones.

Hydromedusa: Hydrozoan medusa.

Hydromedusae: Plural of hydromedusa.

Hydrorhiza: Horizontal rootlike stolon of a hydroid colony that grows over the substratum.

Hydrorhizae: Plural of hydrorhiza.

Mesoglea: Connective tissue layer between the epidermis and gastrodermis of cnidarians and ctenophores.

Nematocyst: Stinging cnida of cnidarians.

Ocelli: Plural of ocellus.

Ocellus: A small cluster of photoreceptors; a simple eye.

Oral Disk: Area around the mouth of an anthozoan polyp which bears eight to several hundred hollow tentacles.

Pedal Disk: In some sea anemones, a flattened disc at the aboral end of the column for attachment.

Planula: A cnidarian larva that is elongated and radially symmetrical but with anterior and posterior ends.

Planulae: Plural of planula.

Septa: Plural of septum.

Septum: A double-walled tissue partition in the radial plane of a cnidarian.

Spirocyst: Cnida with a long adhesive thread that functions in capture of prey and in attachment to a substratum.

Tentacle: Evagination of the body wall surrounding the mouth which aids in the capture and ingestion of food.

Zooxanthella: A golden-brown alga, usually a dinoflagellate, that is symbiotic with various marine animals, especially cnidarians.

Zooxanthellae: Plural of zooxanthella.

Diadumene lineata image
Diadumene lineata