Download Gonionemus vertens

Clinging jellyfish (Gonionemus vertens)
Photo © David Wrobel, www.jellieszone.com
Common names
in English
Clinging jellyfish. Orange striped jellyfish. “Spider” medusa.
… and in other languages
Dutch: Kruiskwal. Dwergkwal.
Scientific name
Gonionemus vertens
Organism group
Cnidarians. Hydrozoa, Olindiidae.
Size and appearance
Hydrozoans are related to jellyfish (Scyphozoa) and to corals and sea
anemones (Anthozoa), but, despite their appearance (and the common
name of this species), they are not in fact true jellyfish. Like other
cnidarians, they alternate between a polyp and a medusa stage.
The mouth of a hydrozoan is surrounded by tentacles, which can be of
many different colours. Using these tentacles, which are equipped with
stinging cells, the animal captures and stuns small fish and
zooplankton and leads its prey to its mouth.
A fully developed medusa of Gonionemus vertens has a number of
small adhesive discs some way along each tentacle (visible as lighter
spots). Its uses them to attach to eelgrass or macroalgae, although it
is also capable of swimming freely. The bell-shaped gastrovascular
cavity is transparent, and within it four orange to yellowish gonads can
be seen, in the shape of a cross. Around the rim of the bell there can
be up to 80 tentacles. The bell of this species has a diameter of around
20–25 mm and can grow to a height of about 35 mm. The tentacles
are roughly 10 mm long and light brown in colour. A distinctive feature
is that they are sharply bent at the tips.
In its polyp stage, the species is only around a millimetre long
(excluding its tentacles). In this entirely benthic stage, too, G. vertens
attaches to algae and eelgrass.
May be confused with
–
Geographical origin
Not entirely clear, but probably the north-west Pacific (China, Korea
and Japan). Possibly also more northerly stretches of the Atlantic coast
of North America. The species was reported from Puget Sound on the
north-west coast of the United States in 1860, and from the east coast
of the US (Massachusetts) in 1894.
First observed in
Swedish waters
In 1923 and 1930, in Gullmarsfjorden on the Skagerrak.
Occurrence in Swedish
seas and coastal areas
?
Occurrence in
other sea areas
Gonionemus vertens is present in Norwegian waters and in Danish
parts of the Kattegat and Belt Sea. In Norway the species was first
discovered in 1921, in Oslofjorden and Trondheimsfjorden; in Denmark
the earliest record is from 1961, off Fredrikshavn.
In the North Sea, the first discovery of G. vertens was in 1913, in
north-east England. In 1929 and 1931 the species was observed on
the Channel coast of Brittany in France. It was subsequently found in
1946–47 on the coasts of Belgium (the port of Ostend) and Germany
(island of Sylt), and in 1960 along the Dutch coast. It is now
considered extinct in German areas of the North Sea. G. vertens also
occurs in the Mediterranean.
In North America the species can be found from Alaska in the north to
California in the south. In the eastern United States, however, it is
now regarded as an introduced species (probably carried by ships from
Europe), despite the early finds there.
Gonionemus vertens is common along the coasts of northern Japan
and Korea (Sea of Japan) and in the Sea of Okhotsk, off the
Kamchatka Peninsula, Sakhalin Island and the southern Kuril Islands.
Probable means
of introduction
Shipping, in ballast water or sediment or as a fouling organism. It is
unclear in which stage transport of the species is more likely to occur.
According to some sources, the species was first introduced to
Portugal and was exported from there to France in 1867, in the polyp
stage and with oysters. Its spread then continued via exports of
oysters from France to other parts of Europe. In the medusa stage,
the species can also disperse in ballast water or with marine currents.
There are also theories about the species having been introduced to
Europe with imported Japanese oysters (Crassostrea gigas) from Japan
or American oysters (Crassostrea virginica) from eastern North
America. According to other theories, polyps of Gonionemus vertens
may have been carried from Norway to the German island of Sylt
during the Second World War by seaplanes travelling between the two
countries. Finds of G. vertens in European aquaria could also be an
indication that the species has spread to northern Europe from the
Mediterranean.
Habitat(s) in which
species occurs
Gonionemus vertens thrives best in temperate waters, and feeds
chiefly on small crustaceans. It lives close to the coast, often in
eelgrass meadows, and can be difficult to discover when attached to
swaying eelgrass. The fact that eelgrass meadows are becoming
increasingly uncommon along the coasts of northern Europe could be a
factor limiting the potential for G. vertens to spread and become more
established.
The species is tolerant and adaptable, and also thrives in aquaria. It
lives in both brackish-water (coastal) and more fully marine (opensea) environments. It probably requires warm water to be able to
reproduce successfully; sexually mature medusae are only found
during the summer months.
Ecological effects
?
Other effects
The stinging cells of Gonionemus vertens operate in the same way as
similar cells in true jellyfish – contact with its tentacles causes sharp
pain and severe irritation of the skin.
G. vertens reportedly has an even more potent sting in its original
environment in the Seas of Okhotsk and Japan. Sensitive humans who
come into contact with its stinging cells in that region may suffer
severe allergic reactions, resulting in the worst cases in fatal
anaphylactic shock.
FIND OUT MORE
•
North European and Baltic Network on Invasive Alien Species: Gonionemus vertens
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State of the Environment: Examples of alien marine species that have become
established in Norwegian waters
http://www.nobanis.org/speciesInfo.asp?taxaID=2955
http://www.environment.no/templates/PageWithRightListing____2249.aspx
•
8,7 MB: Bundesanstalt für Gewässerkunde: Neozoa (Makrozoobenthos) an
der deutschen Nordseeküste: Eine Übersicht.
http://www.stefannehring.de/downloads/083_Nehring+Leuchs-1999_BfG-Bericht-1200_neozoa-nordsee.pdf
Baltic Sea Alien Species Database: Gonionemus vertens
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Stichting Anemoon: Kruiskwal
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De Onderwaterwereld: Gonionemus vertens
http://www.onderwaterwereld.net/oww_ml/php/data.php?PHPSESSID=
d4be9db9441c319306abf2571d791fe8&TLC=NL&SOC=KWPOL&SSC=Gonionemus%20vertens
3,4 MB: Nationaal Natuurhistorisch Museum: Non-indigenous marine and estuarine
species in The Netherlands: Gonionemus vertens
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http://www.ku.lt/nemo/directory_details.php?sp_name=Gonionemus+vertens
http://www.anemoon.org/soorten/coelenterata/Gonver01.html
http://www.marbee.fmns.rug.nl/pdf/marbee/2005-Wolf-ZoolMed.pdf
•
Marine and estaurine macroinvertebrates, macroalgae and fish introduced to
the Netherlands: Gonionemus vertens
http://home.hetnet.nl/~faassema/Gonionemusvertens.html
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Natuurlijk mooi: Gonionemus vertens
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Duikschool The SeaMasters vzw: De kleine giftige kruiskwal
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Kruiskwal (Dwergkwal)
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De Digitale School: Kruiskwal (Gonionemus vertens)
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Joint Nature Conservation Committee: Gonionemus vertens
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University of Liverpool: Invasive Non-native Species in the UK
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Muséum de Genève: Hydrozoa Directory: Gonionemus vertens
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European Nature Information System Database (EUNIS): Gonionemus vertens
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Robots4Farms: Scuba Diving Pictures: Vancouver Island, Canada: Clinging jellyfish
http://www.robots4farms.com/scubadivingpictures_files/porthardy_files/jhs_c_Jellyfish_90p_P7080017.jpg
US Geological Survey: Nonindigenous Aquatic Species: Gonionemus vertens
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http://www.natuurlijkmooi.net/zeeland/kwallen/gonionemus_vertens.htm
http://www.seamasters.be/bio/kruiskwal.htm
http://www.seamasters.be/bio/netel/kruiskwal.htm
http://www.digischool.nl/bi/onderwaterbiologie/html/biologie/zeeland/kruiskwal.htm
http://www.jncc.gov.uk/page-1681
http://138.253.199.114/IAAP%20Web/IAAPwebsite/Marinesppintro2.asp?ID=22
http://www.ville-ge.ch/musinfo/mhng/hydrozoa/limno/gonionemus-vertens.htm
http://eunis.eea.europa.eu/species-factsheet.jsp?idSpecies=37768&idSpeciesLink=37768
http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=2376
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The JelliesZone: Jellyfish and other gelatinous zooplankton: Gonionemus vertens
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UN Atlas of the Oceans: The Ocean and Man's Health
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Alamy Images: Clinging jelly fish
http://jellieszone.com/gonionemus.htm
http://www.oceansatlas.org/unatlas/-ATLAS-/chapter13.html
http://www.alamy.com/stock_photography/3/1/David+Fleetham/AP4YJE.html
PHOTO CREDIT
©
David Wrobel,
http://www.jellieszone.com
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This factsheet on Gonionemus vertens was created on 30 November 2006
First update: 16 December 2006
Translated by Martin Naylor on 12 January 2007