Mnemiopsis leidyi (sea walnut)
- 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
- Air Temperature
- Water Tolerances
- Natural enemies
- Notes on Natural Enemies
- Pathway Causes
- Pathway Vectors
- Economic Impact
- Environmental Impact
- Threatened Species
- Risk and Impact Factors
- Uses List
- Similarities to Other Species/Conditions
- Prevention and Control
- Links to Websites
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Mnemiopsis leidyi A. Agassiz, 1865
Preferred Common Name
- sea walnut
Other Scientific Names
- Mnemiopsis gardeni L. Agassiz, 1860
- Mnemiopsis mccradyi Mayer, 1900
Local Common Names
- Denmark: amerikansk ribbegople
- Finland: amerikankampamaneetti
- Germany: Meerwalnuss; Rippenqualle
- Lithuania: mnemiopsis
- Netherlands: Amerikaanse langlobribkwal
- Norway: amerikansk kammanet; amerikansk lobemanet
- UK: American comb jelly; comb jelly; comb jellyfish; sea gooseberry; warty comb jelly
Summary of InvasivenessTop of page
The native habitat of the ctenophore M. leidyi is the Atlantic coast of North and South America where it can live over a broad range of salinity and temperature conditions. M. leidyi is a polymorphic species with wide environmental tolerance and high phenotypic variability. It may reach high numbers in conditions of abundant prey (zooplankton concentrations) in optimal salinity and temperature conditions in native areas. It is a self-fertilizing hermaphrodite, pre-adapted to rapid colonization (Kremer, 1976). Pianka reported that up to 100% normal development has been repeatedly obtained from self-fertilized eggs of single ctenophores, and the significance of out-breeding in ctenophores is controversial. In addition, M. leidyi has an ability to regenerate from fragments larger than one quarter of an individual. It is also a generalist carnivorous feeder. It was accidentally introduced first into the Black Sea in the early 1980s, possibly with ballast water from the northwestern Atlantic coastal region. From the Black Sea, it spread north to the Sea of Azov, south to the Sea of Marmara and to the eastern Mediterranean. In 1999, it reached the Caspian where it is currently expanding at an even more rapid rate than in the Black Sea. In 2005, it was found in the Adriatic Sea. In 2006, it was first recorded in the North Sea and the Baltic Sea.
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Metazoa
- Phylum: Ctenophora
- Class: Tentaculata
- Order: Lobata
- Family: Bolinopsidae
- Genus: Mnemiopsis
- Species: Mnemiopsis leidyi
Notes on Taxonomy and NomenclatureTop of page
Until recently, three species were included in the Mnemiopsis genus: M. gardeni, M. leidyi and M. mccrady (Moser, 1908, 1909; Mayer, 1912; Main, 1928; Pratt, 1935). When the genus Mnemiopsis appeared in the Black Sea observations of the new ctenophore were significantly aggravated by the inconsistencies between the descriptions of the morphological features of the Mnemiopsis genus by researchers (L. Agassiz, 1860; A. Agassiz, 1865; Fewkes, 1881) and the later descriptions of this genus by Mayer (1912), Main (1928), and Pratt (1935).
DescriptionTop of page
M. leidyi is characterized by the presence of two large mobile lobes referred to as lateral or oral lobes). The oral lobes are derivatives of the ctenophore body (spherosome). Four smaller lobes are situated under the two principal oral lobes. Closing over one another by their distal edges, they completely envelop the mouth area of the animal (Agassiz, 1860; Mayer, 1912; Seravin, 1994).
Under the oral lobes, four smaller lobes are located called auricles. When oral lobes are closed, they completely cover the auricles. At the oral edge of the body, on either flattened side, there is a tentacular apparatus. The central part of the tentacular apparatus is located above the lip of the slit-like mouth. Right and left of the tentacular bulb, fascicles of thin tentacles extend over the sides of the body following special deep grooves. Both sides of the long slit-like mouth are bordered with a row of short simple tentacles, which are continuous with those of the deep lateral furrows.
DistributionTop of page
M. leidyi was first discovered in the northwestern Black Sea in November 1982 (Pereladov, 1988) where it most probably was introduced with ballast waters from the northern American coastal area. By the autumn of 1988 it was found everywhere in the Black Sea (Vinogradov et al., 1989). M. leidyi spread to the Sea of Azov via the Kerch Strait in August 1988 (Studenikina et al., 1991); a first peak followed in September 1989. It can live in the Sea of Azov only during warm seasons, dying when temperature reaches 3°C and re-appears every spring or summer depending on direction of the current (Shiganova et al., 2001). Then probably in 1989-1990 it spread to the Sea of Marmara with the Black Sea currents (Shiganova, 1993). It now occurs year-round in the upper water layer of the Sea of Marmara. M. leidyi was first recorded in Saronikos Gulf during late spring-summer 1990, as well as in the neighbouring, eutrophic Elefsis Bay (Aegean Sea). Swarms were observed during summer in several coastal areas of the Aegean Sea (Skyros, Limnos and Alonissos Islands, Halkidiki Peninsula) in 1991-1996. Furthermore M. leidyi populations were rare along the Limnos coasts in summer 1997, 1998, and 1999 (Shiganova et al., 2001). Further east, M. leidyi appeared in Mersin Bay in spring 1992 (Kideys and Niermann, 1994), and in Syrian coastal waters in October 1993 (Shiganova, 1997).
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.Last updated: 10 Feb 2022
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|Azerbaijan||Present||Original citation: Shiganova et al. (2004)|
|Georgia||Present||Introduced||First reported: 1980 - 1989|
|Iran||Present||Original citation: Shiganova et al. (2004)|
|Syria||Present||Original citation: Shiganova et al. (2001)|
|Turkey||Present||Introduced||First reported: 1980 - 1989|
|Turkmenistan||Present||Original citation: Shiganova et al. (2004)|
|Bulgaria||Present||Introduced||First reported: 1980 - 1989|
|Greece||Present||Introduced||First reported: 1980 - 1989|
|Romania||Present||Introduced||First reported: 1980 - 1989|
|Russia||Present, Widespread||Introduced||1999||Invasive||First found in Caspian Sea in 1999|
|Atlantic - Northeast||Present|
|Atlantic - Western Central||Present||Native||As Mnemiopsis sp.|
|Mediterranean and Black Sea||Present||Introduced||Invasive|
History of Introduction and SpreadTop of page
The native habitat of the ctenophore, Mnemiopsis, is the temperate to subtropical estuaries along the Atlantic coast of North and South America (Kremer, 1994; Mianzan, 1999).
Risk of IntroductionTop of page
M. leidyi is able to occupy and establish itself in any temperate or subtropical productive or eutrophicated coastal area, semi-closed seas or estuaries where salinity is not less than 4‰ and temperature not higher than 28°C.
Habitat ListTop of page
|Brackish||Inland saline areas||Present, no further details|
|Littoral||Coastal areas||Present, no further details|
|Brackish||Estuaries||Present, no further details|
|Marine||Inshore marine||Present, no further details|
|Marine||Pelagic zone (offshore)||Present, no further details|
|Marine||Benthic zone||Present, no further details|
Biology and EcologyTop of page
M. leidyi is a hermaphrodite with two fascicles of gonads (ovaries and testicles) in its gastrodermis. The gonads of the Black Sea Mnemiopsis are located along eight meridional canals of the gastrovascular system. They are localized in the spaces between the ctens (comb flappers). The rows of ovaries face the principal symmetry planes - saggital and tentacular. On the opposite side of each meridional canal, rows of testicles extend. Thus, in adjacent canals, the rows of testicles are arranged in a mirror-like manner, which is characteristic of Lobata. Gonads are formed in the central parts of the canals from the level of the statocyst almost up to the extreme ctens toward the oral edge of the body.
Optimal conditions for M. leidyi are temporal or subtropical climates. Climatic conditions control epidemics of M. leidyi even in optimal environments and spread to adjacent seas from the Black Sea to the Sea of Azov or eastern Mediterranean or from the Southern Caspian to the Middle and Northern Caspian (Shiganova et al., 2007).
ClimateTop of page
|C - Temperate/Mesothermal climate||Preferred||Average temp. of coldest month > 0°C and < 18°C, mean warmest month > 10°C|
Air TemperatureTop of page
|Parameter||Lower limit||Upper limit|
|Absolute minimum temperature (ºC)||2||3|
|Mean annual temperature (ºC)||20||25|
|Mean maximum temperature of hottest month (ºC)||27||31|
|Mean minimum temperature of coldest month (ºC)||4||6|
Water TolerancesTop of page
|Parameter||Minimum Value||Maximum Value||Typical Value||Status||Life Stage||Notes|
|Depth (m b.s.l.)||25||50||Optimum||100 m+ tolerated. Present in the upper layer above the thermocline in warm seasons; in upper layer up to 25-50 m during other seasons. During unfavourable conditions they go down and stay near bottom|
|Dissolved oxygen (mg/l)||>1||Optimum|
|Salinity (part per thousand)||6||25||Optimum||4-39 tolerated|
|Water temperature (ºC temperature)||23||26||Optimum||6-31 tolerated|
Natural enemiesTop of page
|Natural enemy||Type||Life stages||Specificity||References||Biological control in||Biological control on|
Notes on Natural EnemiesTop of page
Only few animals are known to feed on M. leidyi, foremost of which are the scyphomedusan Chysaora quinquecirrha and the ctenophore Beroe ovata (Purcell et al., 2001).
Pathway CausesTop of page
|Interconnected waterways||Yes||Shiganova et al. (2001)|
Pathway VectorsTop of page
Economic ImpactTop of page
Losses for fishery industry are large for countries surrounding the Black, Azov and Caspian Sea areas.
Environmental ImpactTop of page
M. leidyi is a real ecosystem engineer. It affects physical conditions of several recipient productive ecosystems; for example in - the decrease in water transparency, hydrochemical - change nutrients contents and biota. After M. leidyi invasion cascading effects occurred at the higher trophic levels, from a decreasing zooplankton stock to collapsing planktivorous fish to dolphins (bottom-up). Similar effects occurred at lower trophic levels: from a decrease in zooplankton stock to an increase in phytoplankton, relaxed from zooplankton grazing pressure (top-down) and from increasing bacterioplankton to increasing zooflagellata and infusoria (Shiganova at al., 2004 a,b).
Threatened SpeciesTop of page
Risk and Impact FactorsTop of page
- Proved invasive outside its native range
- Has a broad native range
- Abundant in its native range
- Highly adaptable to different environments
- Is a habitat generalist
- Pioneering in disturbed areas
- Capable of securing and ingesting a wide range of food
- Highly mobile locally
- Fast growing
- Has high reproductive potential
- Has high genetic variability
- Altered trophic level
- Damaged ecosystem services
- Ecosystem change/ habitat alteration
- Increases vulnerability to invasions
- Modification of hydrology
- Modification of natural benthic communities
- Modification of nutrient regime
- Modification of successional patterns
- Negatively impacts aquaculture/fisheries
- Negatively impacts tourism
- Competition - monopolizing resources
- Pest and disease transmission
- Interaction with other invasive species
- Rapid growth
- Highly likely to be transported internationally accidentally
Uses ListTop of page
- Research model
Similarities to Other Species/ConditionsTop of page
M. leidyi may be mixed with other representatives of another Lobata species of genus Bolinopsis. B. infundibuilum, occursin the northern Atlantic, North, Baltic and Barrens Sea (Greve, 1970; Seravin, 1998) and the subtropical species B. vitrea, which occurs in the Mediterranean Sea and southern coastal America (Shiganova et al., 2004c; Oliveiro and Migotto, 2006). Oral lobes of both species originate about half-way between the mouth and the infundibulum while in M. leidyi oral lobes originate near the level of the infundibulum.
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.
There should be strict control of ballast waters in harbours to avoid introduction of alien species.
ReferencesTop of page
Faasse MA, Bayha KM, 2006. The ctenophore Mnemiopsis leidyi A. Agassiz 1865 in coastal waters of the Netherlands: an unrecognized invasion? Aquatic Invasions, 1(4):270-277. http://www.aquaticinvasions.ru/2006/AI_2006_1_4_Faasse_Bayha.pdf
GESAMP, 1997. Opportunistic settlers and the problem of the ctenophore Mnemiopsis leidyi invasion in the Black Sea. IMO/FAO/UNESCO-IOC/WMO/WHO/IAEA/UN/UNEP Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection. GESAMP.
Ivanov VI, Kamakim AM, Ushivtzev VB, Shiganova T, Zhukova O, Aladin N, Wilson SI, Harbison GR, Dumont HJ, 2000. Invasion of Caspian Sea by the comb jellyfish M.leidyi (Ctenophora). Jour. Biological Invasions, 2:255-258.
Konsulov A, Kamburska L, 1997. Sensivity to Antropogenic Factors of the Plankton Fauna Adjacent to the Bulgarian Coast of the Black Sea. In: Sensitivity of North Sea, Baltic Sea and Black Sea to Antropogenic and Climatic Changes [ed. by Ozsoy E, Mikaelyan A] Dordrecht, Netherlands: Kluwer Academic Publishers, 95-105.
Kremer P, 1975. Excretion and body composition of the ctenophore Mnemiopsis leidyi (A. Agassiz): comparisons and consequences. In: 10th European Symposium on Marine Biology [ed. by Persoone G, Jaspers E] Weeteren, Belgium: Universa Press, 351-362.
Kremer P, 1976. Population dynamics and ecological energetics of a pulsed zooplankton predator, the ctenophore Mnemiopsis leidyi. In: Estuarine Processes [ed. by Wiley M] New York, USA: Academic Press, 197-215.
Moser F, 1909. No English title available. (Die Ctenophoren der Deutschen Sudpolar- Expedition 1901-1903. Deutsche Subdpolar - Expedition 1901-1903 in Auftrage des Reichsamets des Innern. Berlin. Druck und Verlag von Georg Reiner.) Zoologie.V, 3:115-192.
Seravin LN, Shiganova TA, Luppova NE, 2002. Investigation history of comb jelly Beroe Ovata (Ctenophora, Atentaculata, Beroida) and certain structural properties of its Black Sea representative. Zool. Zh, 81(10):1193-1201.
Shiganova TA, 1997. Mnemiopsis leidyi abundance in the Black Sea and its impact on the pelagic community. In: Sensitivity of North Sea, Baltic Sea and Black Sea to Antropogenic and Climatic Changes [ed. by Ozsoy E, Mikaelyan A] Dordrecht, Netherlands: Kluwer Academic Publishers, 117-130.
Shiganova TA, 2000. Review of research of biology of invader Mnemiopsis leidyi (A.Agassiz) in the Black Sea. In: Ctenophore Mnemiopsis leidyi (A.Agassiz) in the Sea of Azov and the Black Sea and its effects on ecosystems [ed. by Volovik SP]: Rostov-on-Don, 33-75.
Shiganova TA, 2004. AgSome results of studying the intruder Mnemiopsis leidyi (A.Agassiz) in the Black Sea. In: Ctenophore Mnemiopsis leidyi in the Black and Azov Seas: Its Biology and Consequences of its Intrusion [ed. by Volovik SP]: Turkish Marine Research Foundation, 26-68.
Shiganova TA, Bulgakova YV, Siokou-Frangou I, Christou ED, Maley A, 2007. Changes in ctenophore Mnemiopsis leidyi phenology and population dynamics linked to environmental variability and climate forcing in its recipient areas of the Southern Seas. Human and Climate forcing of Zooplankton Populations. In: International Zooplankton Production Symposium. 28 May-1 June 2007, Hiroshima, Japan.
Shiganova TA, Dumont H, Sokolsky AF, Kamakin AM, Tinenkova D, Kurasheva EK, 2004. Population dynamics of Mnemiopsis leidyi in the Caspian Sea, and effects on the Caspian ecosystem. In: Aquatic Invasions in the Black, Caspian, and Mediterranean Seas, Nato Science Series: IV: Earth and Environmental Sciences [ed. by Dumont HT, Shiganova TA, Niermann U], 71-111.
Shiganova TA, Dumont HJD, Mikaelyan AS, Glazov DM, Bulgakova YV, Musaeva EI, Sorokin PY, Pautova LA, Mirzoyan ZA, Studenikina EI, 2004. Interaction between the Invading Ctenophores Mnemiopsis leidyi (A. Agassiz) and Beroe ovata Mayer 1912, and their Influence on the Pelagic Ecosystem of the Northeastern Black Sea. In: Aquatic Invasions in the Black, Caspian, and Mediterranean Seas. Nato Science Series: IV: Earth and Environmental Sciences [ed. by Dumont HT, Shiganova TA, Niermann U], 33-70.
Shiganova TA, Kamakin AM, Zhukova OP, Ushivtzev VB, Dulimov AB, Musaeva EI, 2001. Invader in the Caspian Sea - ctenophore Mnemiopsis and initial results of its effect on the pelagic ecosystem. Oceanology, 41(4):542-549.
Shiganova TA, Mirzoyan ZA, Studenikina EA, Volovik SP, Siokou-Frangou I, Zervoudaki S, Christou ED, Skirta AY, Dumont H, 2001. Population development of the invader ctenophore Mnemiopsis leidyi in the Black Sea and other seas of the Mediterranean basin. Marine Biol, 139:431-445.
Shiganova TA, Musaeva EI, Bulgakova YV, Mirzoyan ZA, Martynyuk ML, 2003. Invaders Ctenophores Mnemiopsis leidyi (A. Agassiz) and Beroe ovata Mayer 1912, and Their Influence on the Pelagic Ecosystem of Northeastern Black Sea. Biology Bulletin, 30(2):180-190.
US Fish and Wildlife Service, 2004. In: Endangered and Threatened Wildlife and Plants; Final Determination of Threatened Status for the Beluga Sturgeon (Huso huso). 69(77) US Fish and Wildlife Service, 21425-21438. http://ecos.fws.gov/docs/federal_register/fr4288.pdf
CABI, Undated. Compendium record. Wallingford, UK: CABI
CABI, Undated a. CABI Compendium: Status as determined by CABI editor. Wallingford, UK: CABI
Faasse M A, Bayha K M, 2006. The ctenophore Mnemiopsis leidyi A. Agassiz 1865 in coastal waters of the Netherlands: an unrecognized invasion? Aquatic Invasions. 1 (4), 270-277. DOI:10.3391/ai.2006.1.4.9
Ivanov V I, Kamakim A M, Ushivtzev V B, Shiganova T, Zhukova O, Aladin N, Wilson S I, Harbison G R, Dumont H J, 2000. Invasion of Caspian Sea by the comb jellyfish M. leidyi (Ctenophora). Jour. Biological Invasions. 255-258.
Konsulov A, Kamburska L, 1997. Sensivity to Antropogenic Factors of the Plankton Fauna Adjacent to the Bulgarian Coast of the Black Sea. In: Sensitivity of North Sea, Baltic Sea and Black Sea to Antropogenic and Climatic Changes. [ed. by Ozsoy E, Mikaelyan A]. Dordrecht, Netherlands: Kluwer Academic Publishers. 95-105.
Pereladov M V, 1988. Some observations for biota of Sudak Bay of the Black Sea. In: III All-Russian conference of marine biology. [III All-Russian conference of marine biology.], 1 Kiev, Russia: Naukova Dumka. 237-238.
Seebens H, Blackburn T M, Dyer E E, Genovesi P, Hulme P E, Jeschke J M, Pagad S, Pyšek P, Winter M, Arianoutsou M, Bacher S, Blasius B, Brundu G, Capinha C, Celesti-Grapow L, Dawson W, Dullinger S, Fuentes N, Jäger H, Kartesz J, Kenis M, Kreft H, Kühn I, Lenzner B, Liebhold A, Mosena A (et al), 2017. No saturation in the accumulation of alien species worldwide. Nature Communications. 8 (2), 14435. http://www.nature.com/articles/ncomms14435
Shiganova T A, Musaeva E I, Bulgakova Y V, Mirzoyan Z A, Martynyuk M L, 2003. Invaders Ctenophores Mnemiopsis leidyi (A. Agassiz) and Beroe ovata Mayer 1912, and their influence on the Pelagic Ecosystem of Northeastern Black Sea. Biology Bulletin. 30 (2), 180-190.
OrganizationsTop of page
Russian Federation: P. P. Shirshov Institute of Oceanology RAS, 36 Nakhimovsky Avenue, 117997 Moscow, http://www.ocean.ru
ContributorsTop of page
04/02/08 Original text by:
Tamara Shiganova, PP Shirshov Inst. of Oceanology, Russian Academy of Sciences, Nakhimovsky avenue, 3617997 Moscow, Russia
Distribution MapsTop of page
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