- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- History of Introduction and Spread
- Risk of Introduction
- Habitat List
- Biology and Ecology
- Notes on Natural Enemies
- Means of Movement and Dispersal
- Economic Impact
- Environmental Impact
- Social Impact
- Risk and Impact Factors
- Detection and Inspection
- Similarities to Other Species/Conditions
- Prevention and Control
- Gaps in Knowledge/Research Needs
- Links to Websites
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Gonionemus vertens A. Agassiz, 1862
Other Scientific Names
- Gonionemus depressus Goto, 1903
- Gonionemus murbachi Mayer, 1901
- Gonionemus murbachii Mayer, 1901
- Gonionemus oshoro Uchida, 1929
- Gonionemus vindobonensis Joseph, 1918
- Haleremita cumulans Schaudinn, 1894
International Common Names
- English: angled hydromedusa; clinging jellyfish; orange-striped jellyfish
Local Common Names
- Netherlands: kruiskwal
Summary of InvasivenessTop of page
G. vertens is a small hydrozoan jellyfish whose type specimen was recorded in Puget Sound, Washington State, USA in 1861 (Agassiz, 1861). The natural range of this nearshore limnomedusa appears to span from southern California through British Columbia, Alsaka and Kamchatka to northern Japan, and also to include the Arctic Ocean. On the Pacific coast of north America it is not common south of Puget Sound (Washington State) but some blooms have appeared farther south such as near Santa Barbara, California (McConnaughey et al., 1986). It is also relatively common on parts of the Atlantic coast of North America (Maine, Massachusetts) although it is not clear if this is a part of its natural range or a result of translocation. Japanese populations appear to be centred along the northwest coast of Honshu from Niigata northwards to Hokkaido, i.e. the eastern shore of the Sea of Japan (Otsuru et al., 1974). This is directly opposite the coastline of eastern Russia and Vladivostok, and the proximity of the Japanese and Russian locations for Gonionemus vertens most probably accounts for the presence of the species in both countries. The spread of this species beyond its natural range (i.e. European waters) is likely to have been influenced by movements of oysters, shipping and marginal spread of established populations (Carlton, 1985). Transport on ships' hulls at the polyp stage from the western Pacific Ocean in the nineteenth century appears to be the most probable mechanism of introduction although hydromedusae can disperse in water currents and ballast water (Carlton, 1985). Specimens were found in Argentinean waters in 2008. Apart from its ability to inflict severe stings on humans in the north-western Pacific ocean (but not most other parts of its range), the species appears to have few adverse effects in either its native or its introduced range.
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Metazoa
- Phylum: Cnidaria
- Class: Hydrozoa
- Order: Limnomedusae
- Family: Olindiasidae
- Genus: Gonionemus
- Species: Gonionemus vertens
Notes on Taxonomy and NomenclatureTop of page
In addition to Gonionemus vertens a number of species and local forms within the genus have been described from different geographical regions, distinguished by the shape and thickness of the bell, and the number of tentacles and statocysts (Edwards, 1976); these are listed by WoRMS (2015), and some examples are described in the 'Description' section of this datasheet. Most are now considered synonymous with G. vertens (WoRMS, 2015).
Early references often list this species as a member of the Trachyline medusae which has now been revised (McConnaughey et al., 1986).
DescriptionTop of page
Cowles (2015), referring to the form found in the coastal waters of Washington State (USA) and British Columbia (Canada) from which the type specimen of G. vertens was collected, describes the species thus: 'This bell-shaped hydromedusa (usually just slightly broader than tall) has about 60-80 unbranched tentacles which are evenly spaced around the margin of the bell. The tentacles have large rings of nematocysts all along their length, and halfway back from the tip of each tentacle is a larger adhesive knob or pad used for attachment to objects. The tentacle tends to bend at the disk. The tentacle bulbs at the base of the tentacles are yellowish-tan. The 4 radial canals are unbranched and continue all the way to the margin of the bell. There are no centripetal canals. Ruffled flap-like orange, red, violet (in females), or yellow-brown (in males) gonads hang down along the 4 radial canals and form a clearly visible X shape. The manubrium is coloured tan and hangs down about to the bell margin, with 4 slightly frilly lips. The bell may be clear or light green (it is unusual for a hydrozoan medusa to be coloured). Diameter to 2.5 cm'. According to Wrobel (undated), referring to the genus Gonionemus as found in the Pacific, the number of statocysts is approximately equal to the number of tentacles.
Species now synonymised (WoRMS, 2015) with G. vertens include: G. murbachii from the northeastern seaboard of North America, which is somewhat shallower than a hemisphere and has 60-80 tentacles, half the number of statocysts, and a stomach smaller than that of G. vertenssensu stricto (Mayer, 1909); G. agassizi from the Aleutian Islands, which is stated to have more tentacles than G. vertenssensu stricto (probably up to 100) and be characterised by a much shallower bell (Murbach and Shearer, 1902, 1903); G. depressum from southern Japan, which has 64 tentacles, about twice as many as statocysts, and a bell shallower than a hemisphere (Goto, 1903); and G. oshoro from northern Japan, which has up to 80 tentacles and about the same number of statocysts, is very shallow with a thin bell, and has fewer gonadial folds than G. murbachii (see Edwards, 1976).
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|Arctic Sea||Present||Romer and Schaudinn, 1906||General distribution, specific site not detailed.|
|Atlantic, Northeast||Present||Introduced||Land et al., 2001; Fofonoff et al., 2015|
|Atlantic, Northwest||Present||Anon, 1980; Fofonoff et al., 2015|
|Atlantic, Southwest||Present, few occurrences||Introduced||2008||Fofonoff et al., 2015||Near Mar del Plata, Argentina|
|Mediterranean and Black Sea||Widespread||Introduced||possibly early 1900s||Land et al., 2001||Broad but patchy distribution throughout Mediterranean sea, not fully defined|
|Pacific, Eastern Central||Present, few occurrences||McConnaughey et al., 1986|
|Pacific, Northeast||Present||Native||Fenner, 1997; Fofonoff et al., 2015|
|Pacific, Northwest||Present||Native||Yakovlev and Vaskovsky, 1993; Fofonoff et al., 2015|
|Japan||Present||Native||Maas, 1909; Otsuru et al., 1974||Centered around north-west coast of Honshu|
|-British Columbia||Present||Native||McClean Fraser, 1942; Fofonoff et al., 2015|
|USA||Present||Native||Uncertain whether east coast populations are native or introduced|
|-Alaska||Present||Native||Murbach and Shearer, 1902; Fofonoff et al., 2015|
|-California||Present, few occurrences||McConnaughey et al., 1986|
|-Florida||Last reported||1901||Mayer, 1901||Dry Tortugas|
|-Maine||Localised||Anon, 1980; Anon, 1980; WoRMS, 2015||Cobscook Bay, Washington County|
|-Massachusetts||Present||Fofonoff et al., 2015; WoRMS, 2015||First recorded at Woods Hole in 1894; disappeared in 1931; reappeared in recent years|
|-New York||Last reported||1898||Hargitt, 1898|
|-Washington||Present||Agassiz, 1861; Cowles, 2015||Type specimen recorded in Puget Sound in 1861|
|Argentina||Present, few occurrences||Introduced||2008||Fofonoff et al., 2015||Near Mar del Plata|
|Belgium||Present||Introduced||possibly early 1900s||Leloup, 1948||Atlantic seaboard|
|France||Localised||Introduced||possibly early 1900s||Leloup, 1948; Leewis, 2002; Müller, 2004; WoRMS, 2015||English Channel and Mediterranean|
|Germany||Present||Introduced||possibly early 1900s||Gollasch and Nehring, 2006||German Bight|
|Italy||Present||Introduced||early 1900s||Nappi, 1918||Bay of Naples|
|Netherlands||Localised||Introduced||Leloup, 1948; Leentvaar, 1961; Bakker, 1980; Leewis, 2002|
|Norway||Present||Introduced||possibly early 1900s||Edwards, 1976||Patchy distribution|
|Russian Federation||Present||Present based on regional distribution.|
|-Eastern Siberia||Present||Native||Fofonoff et al., 2015|
|-Russian Far East||Present||Yakovlev and Vaskovsky, 1993|
|Scandinavia||Widespread||Introduced||possibly early 1900s||Leloup, 1948||Skaggerak, broad but patchy distribution|
|UK||Widespread||Introduced||possibly early 1900s||Eno et al., 1997||Patchy distribution around British coasts, low density|
History of Introduction and SpreadTop of page
This species shows a variable, generally moderate rate of spread beyond its natural range in the North Pacific (and possibly the Atlantic coast of North America -- see Summary of Invasiveness). It is thought to have been initially introduced to Europe in Portugal where the population was localised due to currents, temperatures and salinities. It was exported from 1867 onwards from Portugal to France, this time attached at the polyp stage to oysters. This mechanism has probably allowed spread to other European countries including the UK and Ireland, since France was a major oyster exporter (Edwards, 1976). By 1960 the species had been recorded from several coastal locations in Europe. Records in Europe are dated from England (1913), Norway (1922), Sweden (1930), France (1930, 1932, 1950), Belgium (1948), northwest Germany (1950), the Mediterranean (1952, 1953), Ireland (1953), and the Netherlands (1960) (Russell, 1953; Leentvaar, 1961).
Edwards (1976) also postulated that G. vertens may have arrived much earlier from Japan with importations of Japanese oysters, Crassostrea gigas, 500 or more years ago; this study also discusses other shipping- and seaplane-associated methods of transport. Nonetheless, the notion of transportation on commercial oysters is supported by the occurrence of medusae in aquaria at Vienna (Austria), Prague (Czech Republic), Cullercoats (UK), Port Erin (Isle of Man), Aberdour (UK) and Dunstaffnage (UK) following the introductions of oysters to the respective facilities (see Edwards, 1976). The exact nature of how the species was presumably translocated from the North Pacific to the Atlantic coast of North America is not known, although commercial shipping or attachment to commercial items again seem probable candidates.
The first report of the species from the south-western Atlantic was in 2008, when specimens were found in an aquarium filled with benthic organisms that had been collected near Mar del Plata, Argentina; shipping is considered to be the likely vector (Fofonoff et al., 2015).
Risk of IntroductionTop of page
G. vertens might be introduced / translocated into new areas via biotic and abiotic pathways. For example, in its medusa form the species can be moved over local scales (within suitable climatic envelopes) by current transport, as for any zooplanktonic species. Areas that introduce non-native oysters (particularly from the North Pacific) for commercial purposes may be at an increased risk as the polyps of G. vertens have been shown to attach to their shells, budding off to produce new medusae if the new site is characterised by suitable environmental parameters. Deliberate introductions of G. vertens itself are highly unlikely as the species has no commercial value and is typically considered a nuisance owing to its potent sting.
HabitatTop of page
This species seems to thrive in temperate to warm-temperate regions. It can be found attached to kelp, eelgrass, and other substrates (e.g. the shells of epibenthic bivalve molluscs) in summer, in at least partly protected waters (Cowles, 2005). Yerkes (1906) suggested that the preferred habitat of G. vertens is sheltered harbours which are affected by the tides, but where these tides are not to strong so as to dislodge the species from the algal fronds it is typically attached to. Any disturbance in the water causes the animals to detach themselves from the object to which they are attached – either by the viscid bodies of the tentacles or the lips of the manubrium – and swim to the surface.
Habitat ListTop of page
|Bays||Present, no further details|
Biology and EcologyTop of page
The conspicuous stage in the dimorphic (i.e. metagenic) life cycle is the small medusa. The polyploid stage is present as a tiny solitary polyp attached to a substrate at the seabed (including mollusc shells) which feeds on protozoa and other small plants and animals. The polyp stage closely resembles Hydra and is seldom seen (McConnaughey et al., 1986).
Physiology and Phenology
A very early, yet detailed, account of feeding in G. vertens is provided by Yerkes (1906). Prey items in Massachusetts consisted of small fishes, crustaceans, larvae of various kinds, and such dead organic material as came within reach. G. vertens were found attached by a few tentacles to a weed, with the exumbrellar surface of the bell against the weed and the manubrium swinging free in the water. It was additionally proposed that the the restricted range of G. vertens (on a localised scale) may relate to the distribution of its food supply, as sheltered coastal regions where the species is abundant are frequently found to contain masses of organic matter (Yerkes, 1906).
G. vertens use adhesive discs near the middle of each tentacle to attach to eelgrass, sea lettuce (Ulva spp.) or various types of algae instead of swimming. They are small (bell diameter to 25 mm) and hard to see when hanging on to swaying seaweed. Nevertheless they are capable of swimming when necessary. In Europe the species has been found in close association with the commercial oyster Crassostrea angulata (Edwards, 1976) which has been proposed as its principal artificial vector for introduction.
This species appears to be adaptable to the seasonal temperature fluctuations found at temperate latitudes and into the Arctic Ocean. Like many gelatinous zooplankton with a metagenic life cycle, it appears to be present year round in its polyp form with the planktonic medusa budding off in late spring/early summer to take advantage of seasonal abundances of its zooplankton prey.
Notes on Natural EnemiesTop of page
No specific studies have been undertaken on the predators of G. vertens. However, the general perception of gelatinous zooplankton within marine food webs as trophic dead ends (or conduits at best) has been radically challenged in recent years with many species now considered to be intrinsic dietary components for an increasing range of vertebrate and invertebrate species (see Arai (2005) for a full review).
Means of Movement and DispersalTop of page
Although typically attached to algae or shellfish near the seabed the medusae are also active swimmers that can propel themselves upward in the water column by rhythmic pulsations of the bell. G. vertens typically swims in bouts of 5 to 10 bell contractions, each bout lasting 1 to 3 s followed by periods of quiescence lasting around 10 to 90 s (Daniel, 1985). Natural mechanisms of dispersal include direct current transport and potential transportation on detached, rafting macroalgae. The introduction of non-native oysters into European waters more than a century ago has been proposed as the principal mechanism by which G. vertens, as attached polyps, became established in the region. This notion is backed up by the presence of species in aquaria in landlocked European countries where oysters were on display. Abiotic dispersal mechanisms include transport of polyps on ships' hulls and medusae in ballast water.
Transport on ships' hulls in the polyp stage (Carlton, 1985) from the western Pacific Ocean in the nineteenth century may be another mechanism of introduction. Edwards (1976) suggested that it may have arrived much earlier from Japan with importations of Japanese oysters, Crassostrea gigas, 500 or more years ago.
Economic ImpactTop of page
No specific economic impacts have been identified to date beyond the localised effects of G. vertens causing severe stings to female swimmers employed to harvest seaweed around Honshu, Japan (Fenner, 1997; see Social Impact section).
Environmental ImpactTop of page
G. vertens feeds largely on zooplanktonic taxa (i.e. copepod crustaceans) which are super-abundant at temperate latitudes, so it would not be expected to have a dramatic impact as an invasive species at an environmental level.
There are no predicted impacts on biodiversity as G. vertens is a mero-planktonic species operating within the extremely diverse planktonic communities found at temperate latitudes. In areas to which it has been accidentally introduced (i.e. Europe’s Atlantic fringe) the species poses no immediate threat in terms of outcompetition of native species.
Social ImpactTop of page
Stings from G. vertens are unusually venomous in parts of its range, and dense shoals of such jellyfish in warm seas pose a danger to swimmers. A sting from G. vertens causes a burning sensation in the skin, which is accompanied by rapid blistering and local oedema, followed in turn by general weakness after 10 to 30 minutes (see Fenner, 1997). However, there appears to be some regional variation regarding the severity of the stings (see Cornelius (1995) and references therein). For example, in the Pacific Northwest of North America G. vertens lacks a sting that is felt by people, but the same species in the Russian Far East is known to be venomous.
Risk and Impact FactorsTop of page Invasiveness
- Proved invasive outside its native range
- Has a broad native range
- Is a habitat generalist
- Capable of securing and ingesting a wide range of food
- Highly mobile locally
- Long lived
- Fast growing
- Has high reproductive potential
- Has propagules that can remain viable for more than one year
- Reproduces asexually
- Modification of natural benthic communities
- Negatively impacts human health
- Negatively impacts aquaculture/fisheries
- Causes allergic responses
- Induces hypersensitivity
- Highly likely to be transported internationally accidentally
- Difficult to identify/detect as a commodity contaminant
- Difficult to identify/detect in the field
- Difficult/costly to control
DiagnosisTop of page
Given the small size of G. vertens medusae (~2.5 cm bell diameter) and the elusive nature of their benthic polyps, the species is normally detected first through medical diagnosis of stings (although it is unlikely that in introduced areas the expertise to attribute stings to a particular species would be available).
Edwards (1976) suggested that G. vertens was introduced into European waters as polyps attached to non-native commercial oysters from the Pacific. Close inspection of oyster shells introduced under such circumstances is worthy of consideration to detect the present of minute benthic polyps.
Detection and InspectionTop of page
A convenient mode of capturing G. vertens proposed by Yerkes (1906) is to disturb the water and then dip-net the medusae as they appear at the surface. Upon reaching the surface they turn over, the mouth of the bell facing upwards, and begin to sink by force of gravity. Under ordinary circumstance the medusae are not at the surface of the water and are attached to seagrass fronds (or similar algae or substrates) at the seabed. It would appear, therefore, that they do not migrate upwards in any definite way for the purpose of feeding or in response to light. Surface towing at night has suggested that there are few, if any, more at the surface than in the daytime. In the light of these suggestions, provisional surveys to assess presence or absence should target sheltered bays and harbours where seagrass beds are present. Given that translocation of G. vertens on the hulls of commercial vessels and/or in ballast water may also be a problem (Edwards, 1976), harbour areas are again a logical place to undertake pilot surveys.
Similarities to Other Species/ConditionsTop of page
Eperetmus typus (Phylum Cnidaria; Class Hydrozoa; Order Limnomedusae; Family Olindiidae) is also deeply bell-shaped and has nematocyst rings on the tentacles, but it has no adhesive pads on the tentacles and the radial canals usually have many centripetal canals.
Melicertum octocostatum (Phylum Cnidaria; Class Hydrozoa; Order Leptomedusae; Family Melicertidae) is found on both coasts of the USA, being relatively common in coastal areas of the North Atlantic, and also found widely in the North Pacific (Bering Sea south to Oregon, USA). M. octocostatumis a near-shore jelly that can also be found in estuaries. It is a fairly distinct hydromedusa, with eight bright yellow or brownish-yellow linear gonads along the radial canals, easily visible through the transparent bell. The bell reaches a maximum length of 14 mm. The stomach is short and broad. Numerous tentacles line the bell margin, with up to 88 large tentacles alternating with smaller ones.
Prevention and ControlTop of page
Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.
Although G. vertens appears to have little adverse effect in most of its range, there are possible prevention and control measures that could be used if necessary.
Ecosystem impacts to a level requiring restorative measures have not been documented to date.
Gaps in Knowledge/Research NeedsTop of page
The most immediate gap in our knowledge of G. vertens relates to population connectivity. Studies focussed on the molecular ecology of the species should therefore be considered a priority.
ReferencesTop of page
Bakker C, 1980. On the distribution of Gonionemus vertens A. Agassiz (Hydrozoa, Limnomedusae), a new species in the eelgrass beds of Lake Grevelingen (S. Netherlands). Hydrobiological Bulletin, 14(3):186-195
Cornelius PFS, 1995. North-west European thecate hydroids and their medusae, Laodiceidea to haleciidae: keys and notes for the identification of the species (North-west European thecate hydroids and their medusae, Laodiceidea to haleciidae: keys and notes for the identification of the species). Linnean Society of London, Estuarine and Coastal Sciences Association and Field Studies Council. [Synopses of the British Fauna (new series), No. 50.]
Cowles D, 2015. Invertebrates of the Salish Sea. Anacortes, Washington, USA: Rosario Beach Marine Laboratory. http://www.wallawalla.edu/academics/departments/biology/rosario/inverts/index.html
Fofonoff PW, Ruiz GM, Steves B, Carlton JT, 2015. California Non-native Estuarine and Marine Organisms (Cal-NEMO) System. Edgewater, Maryland, USA: Smithsonian Environmental Research Center. http://invasions.si.edu/nemesis/calnemo/intro.html
Goto S, 1903. The Craspedote Medusa Olindias and Some of its Natural Allies. In: Mark Anniversary Volume [ed. by Parker, G.H.]. New York, USA: Henry Holt and Company, 1-22 (and plates I-III). http://www.biodiversitylibrary.org/item/16789#page/25/mode/1up
Land J van der, Vervoort W, Cairns SD, Schuchert P, 2001. Hydrozoa. In: Costello MJ, Emblow CS, White R, eds. European register of marine species: a check-list of the marine species in Europe and a bibliography of guides to their identification. Paris, France: Muséum national d'Histoire naturelle, 112-120. [Collection Patrimoines Naturels, 50]
Leentvaar P, 1961. Two interesting invertebrates, Limnadia lenticularis (L.)(Crustacea Phyllopoda) and Gonionemus vertens A. Agassiz (Limnomedusae), found in the Netherlands. Zoologische Mededelingen, 14:225-231
Leloup E, 1948. Presence of the trachymedusoid, Gonionemus murbachi Mayer, A.G. 1901, on the Belgian coast. (Présence de la trachyméduse, Gonionemus murbachi Mayer, A.G. 1901, à la côte belge). [Contrubution à l'étude de la faune belge, no. 16]
Maas O, 1909. Contributions to the natural history of East Asia: Japanese Medusae. (Beiträge zur Naturgeschiche Ostasiens: Japanische Medusen.) Abhandl. Math. Phys. Klasse de K. Bayer. Acad. der Wissenschaft Munchen, Abhandl 8(suppl. bol. 1). 4-65
Otsuru M, Sekikawa H, Hiroli Y, Suzuki T, Sato Y, Shirakat T, Nagashima T, 1974. Observations on the sting occurring amongst swimmers in the rocky seashore. Japanese Journal of Sanitary Zoology, 24:225-235
WoRMS, 2015. World Register of Marine Species. http://www.marinespecies.org/
Wrobel D, undated. JelliesZone. http://jellieszone.com/
ContributorsTop of page
14/06/10 Original text by:
Jonathan Houghton, Institute of Environmental Sustainability, School of the Environment & Society, Swansea University, Singleton Park, Swansea SA2 8PP, UK
Distribution MapsTop of page
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