Cours de zoologie (1ère année). by Pierre Fascicule I, Protozoaires, spongiaires, cnidaires, plathelminthes, némathelminthes. by Pierre Binet. Print book. Get this from a library! Cours de zoologie. Fascicule I, Protozoaires, spongiaires, cnidaires, plathelminthes, némathelminthes. [Pierre Binet]. Les Cnidaires hébergent leurs symbiotes dans les cellules du études ont analysé la réponse de Symbiodinium au cours de différents stress.

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This article is an open-access article distributed under the terms and conditions of the Creative Commons Attribution license http: The toxicity of Cnidaria is a subject of concern due to its influence on humans. In particular, courz blooms can highly affect human economical activities, such as bathing, cohrs, tourism, etc. Stinging structures of Cnidaria nematocysts produce remarkable effects on human skin, such as erythema, swelling, burning and vesicles, and at times further severe dermonecrotic, cardio- and neurotoxic effects, which are particularly dangerous in sensitive subjects.

In cnidiares zones the toxicity of jellyfish is a very important health problem, thus it has stimulated the research on these organisms; to date toxicological research on Cnidarian venoms in the Mediterranean region is not well developed due to the weak poisonousness of venoms of jellyfish and anemones living in this area.

This paper reviews the knowledge on this jellyfish species, particularly considering its occurrence and toxicity. The mauve stinger Pelagia noctiluca Cnidaria: Scyphozoa is a small pelagic jellyfish generally pink- mauve- or light brown-coloured, with a phosphorescent bell measuring 3 to 12 cm in diameter in adult specimens, whose edge is provided with lappets and tentacles; in this species the nematocysts stud the tentacles, the oral arms, as well as the upper surface of the bell [ 1 ].

Pelagia noctiluca has direct development, so its cycle do not comprise the benthic scyphistoma stage. Pelagia noctiluca was collected in intertidal zones of the Pacific Ocean along the Californian coast [ 4 ] and is widely distributed in the Mediterranean Sea and in some zones of the Atlantic Ocean. In Atlantic waters it is frequent along the Southern Atlantic French coast in summer [ 5 ]; it was observed repeatedly in swarms around the British Islands [ 6 ], and in the North Sea and also, although infrequently, off the Dutch coast [ 78 ].

Strandings of Pelagia noctiluca were observed in on beaches of the western coast of Ireland [ 9 ]. In the Mediterranean Sea swarms of Pelagia noctiluca occur usually in pelagic waters from March to May; in summer months, from June and August, isolated big specimens courd also appear [ 12 ]. In the Southwestern Mediterranean this Cnidarian was indicated as the most frequent jellyfish along Tunisian coasts, mostly in autumn and winter; in this area the presence of Pelagia noctiluca depends on local and cjidaires winds and currents [ 13 ].

Anyhow, this species was signalized as uncommon along Tunisian coasts [ 1415 ] and in front of Algeria [ 16 ]. In that years the proliferation of other species, such as Rhizostoma pulmoCotylorhiza tuberculataAurelia aurita and Chrysaora hysoscellawas recorded at a lesser extent and caused less health problems because of their scant poisonousness.

The Pelagia noctiluca bloom started in the Eastern Basin and in the Adriatic Sea the latter was overall the most interested by the phenomenon and subsequently spread to the Western Basin, although with less intensity.

The main period concerned was —; then, as suddenly it arose, the phenomenon finished quickly, even though sporadic proliferations were recorded in subsequent years. In the Eastern Mediterranean the studies concerning the distribution of Pelagia noctiluca and of other jellyfish were carried out mainly during summer [ 19 ]; some scientists performed research on cnidaies occurrence of this jellyfish in Greek and Egyptian waters [ 20 ], along Turkey [ 2122 ] and Lebanese coasts [ 23 ], and lessepsian jellyfish species coming from the Red Sea were observed in Israeli waters [ 2425 ].

Along Maltese coasts the studies on the distribution of Pelagia noctiluca were carried out from to [ 26 ].

In the Adriatic Sea Pelagia noctiluca caused several problems to bathers and sea-workers and its distribution was studied along Croat coasts during the summer of [ 27 ] and seasonally in [ 28 ], and along Italian coasts during the period —, mainly during the summer months, when its occurrence and seasonal variations were related with the variations of environmental factors [ 2029 — 32 ]. The influence of water temperature on swimming behaviour of Pelagia noctiluca was emphasized [ 33 ]; this factor could account for coastal aggregations occurring in the Adriatic coasts in summer.

After research performed from toaccording to [ 34 ] the highest densities of Pelagia noctiluca in the Adriatic Sea were recorded in pelagic waters with high salinity and low nutrients. It was asserted that the dense aggregations of this organism in coastal shallow waters were wind- current- and tide-caused [ 35 ].

In the Tyrrhenian Sea and in the Ligurian Sea the consequences of the bloom were remarkably lower than in other Mediterranean zones; nevertheless, notable alterations in comparison with the normal situation were recorded everywhere from to [ 2036 — 42 ].

Furthermore, in some receptive coastal zones, such as in cous Spotorno Bay Western Ligurian Rivierathe proliferation of Pelagia noctiluca was evident and cnnidaires a peak during some periods September — January with no apparent regard to the season [ 43 ].

On the whole, salinity was indicated to exert an influence on jellyfish behaviour and distribution as evidenced in field observations [ 45 ].

An univocal explanation of the jellyfish bloom and of the subsequent jellyfish decrease was not supplied and several scientists provided different explanations for the blooms, but it seemed acceptable that neither cnidairess changes as water circulation didn’t show clear alterations during last decades nor pollutant inputs supported jellyfish proliferation.

It was suggested that coastal aggregation of jellyfish could be due to wind action [ 26 ], to natural [ 41 ] or cyclic [ 42 ] fluctuations of jellyfish populations or to water movements [ 46 ]. Furthermore, a relationship between jellyfish courd and environmental factors [ 2328 ] or water pollution [ 4748 ] was suggested. Recently, the cumulative effects of man-caused and climate changes has been indicated to be involved in the mechanisms which can promote the increasing of jellyfish occurrence [ 5152 ].


In particular, it was stated that as Cnidaria feed high on marine food chains and therefore they can compete with fishes for food, massive removal of top-predator fishes by commercial fishing efforts could open up food resources for jellyfish [ 51 ]. In addition, models indicated that the predicted pH decrease in oceans with rising Cnidairws 2 could induce long-term jellyfish increase over the next years [ 52 ].

Jellyfish blooms have also stimulated research on the biological, ecological and chemical aspects of Pelagia noctilucawhich has been carried out in order to cojrs its role in the marine ecosystem and in the food web. The biological cycle of Pelagia noctiluca is annual [ 3 ]; for courd reason it shows couts natural mortality, cnidires of short life-cycle species [ 32 ]. Its reproductive period was also extensively studied and it was observed that Pelagia noctiluca reproduces throughout the year [ 53 ].

In studies concerning the lipid composition of Pelagia noctiluca [ 56 ] it vnidaires observed that total lipids are 0. Among neutral dours mainly sterol esters A high amount of free fatty acids Proteins in Pelagia noctiluca range from Preliminary results of HPLC analyses on Pelagia noctiluca crude extracts partially separated by gradient density showed that a noticeable amount of the extract was of protein nature; this result was also confirmed by protein analyses [ cojrs ].

N ratio of 4. Sphingophosphonolipid composition of Pelagia noctiluca was recently defined and a suite of two ceramide 2-aminoethylphosphonic acids CAEP was quantified at 2. The pH of body fluids taken from Pelagia noctiluca collected in the intertidal zone from Laguna Beach California was also performed; the results showed a pH ranging from 7.

The morphology of nematocysts of Pelagia noctiluca was observed during early twentieth century [ 6667 ]; subsequently [ 6 ] three types of nematocysts were described: Subsequently two predominant types of nematocysts were referred to be found on Pelagia tentacles: On the whole, P.

More recent studies showed five morphological types that have been differentiated according to the classification of Mariscal ncidaires 7172 ]: Subsequently, these types were better defined by ultrastructural studies [ 68 ] as follows: Recently, the morphology of Pelagia noctiluca nematocysts was re-examined [ 59 ] and the nematocysts found were separated in three groups including different morphological types: The nematocysts of Pelagia noctiluca can be found on umbrella, oral arms and tentacles; thus all the jellyfish is venomous and discharge can be induced, aside from encounters with the living animal, even from handling stranded or dead organisms [ 73 ].

The nematocysts of Pelagia noctiluca can be maintained isolated in distilled water where they retain their discharging capacity [ cnidares ].

The nematocysts of Pelagia noctiluca may be triggered by vinegar [ 76 ]. It is well known that jellyfish stings can induce both local and general cpurs [ 83 ] and sometimes can be lethal to humans [ 84 ]. In general, though, jellyfish stings usually cause a mild local dermatitis; so serious or fatal systemic reactions are uncommon [ 85 ].

After envenomation some neuromuscular manifestations such as localised neuropathy and mononeuritis multiplex [ 86 — 88 ] as well as neurological manifestations such as delirium, stupor, central respiratory failure and muscular weakness have been reported [ 85 ].

Pelagia noctiluca stings are usually limited to the skin surface and cause only erythematous, edematous, and vesicular topical lesions [ coura91 ], with local pain which persists for 1—2 weeks [ 91 ], while systemic complications or cutaneous infections are infrequent [ 92 ]. Nevertheless, dramatic immediate reactions have been observed after Pelagia noctiluca stings, even though they are rarely severe and prolonged; the lesions appear circinate or irregularly shaped, the venom is also able to cause severe generalized allergy with bronchospasm, pruritus and postinflammatory hyperpigmentation [ 93 ].

Immediate pain, distress, occurrence of urticaria-like lesions and dyspnoea after massive stingings were reported [ 94 ]. Pelagia noctiluca stings can leave scars and hyperpigmentation; the persistence of pigmentation can result from tattooing of the mauve stinger pigment into the skin or from post-inflammatory cnisaires [ 83 ].

Hyperpigmentation can remain for some years after envenomation causing aestethical problems [ 7392 ]. It was reported that jellyfish probably identificated as Pelagia noctiluca caused recurrent and more severe cutaneous eruptions over ten days after coyrs [ 97 ]. Stinging by Pelagia noctiluca can provoke courrs of the eruption after some years, also without further contact with jellyfish; thus was hypothesized the venom could react with dermal collagen and produce an active antigen which stimulates the immunological response [ 91 ckurs.

Cross-reactions against venom of Physalia physalis was observed in patients showing significant titers of IgG against crude extract of nematocysts of Pelagia noctiluca [ 98 ]. Anyhow, the seriousness of envenomation is due to the eventual allergic characteristics of the patient or to previous envenomations [ courd ].

The jellyfish bloom gave rise to epidemiological studies, which were carried out mostly in the Adriatic area [ 99 — ] and in the Eastern Mediterranean region [ ]. In the zone of Trieste Italy from to subjects come into contact with Pelagia noctiluca and suffered from skin and systemic injuries mainly cors local symptoms; only five cases, whose atopy was ascertained through family and personal history, cnldaires more severe general symptoms [ ].

Cnidairess Greek waters subjects, mainly adults, required medical advice from toparticularly in July and August during the swimming period; Cnidires the whole in Adriatic coastal zones bathing was significantly influenced by the bloom [ ].

Otherwise, a scarce incidence of dermatitis caused by Pelagia noctiluca was emphasized in the Ligurian region where the observed cases were of scarce clinical relevance: The problem of the separation of nematocysts from tissue material has cousr dealt with by several scientists. As already reported for other Cnidaria [ 72— ], in the case of Pelagia noctiluca the toxicity is not exclusively due to nematocysts, but is also ascribable to tissue components [ ].

Recent laboratory data showed the nematocysts of Pelagia noctiluca can be separated by centrifugation using the discontinuous density gradient of Percoll [ 59 ].


In addition, the preservation of the nematocysts of Pelagia noctiluca depends cnidairez maintenance method and particularly on temperature freezing and pH neutral values are optimal [ ]. In other studies the nematocysts from marginal tentacles of Pelagia noctiluca were isolated and partially purified; then lyophilised fractions of homogenate preparations of nematocysts were fractionated on Sephadex G columns, the molecular weight cnidairres determined and fractions were tested to evaluate the effect on heart activity coours rats and on neuromuscular activity of frogs.

The results showed an evident toxic activity of unfractioned pools on neuromuscular synapses and less myocardial effects with only few variations of cardiac frequency [ 72 ].

Preparations of intact nematocysts were tested on hairless mice and on human skin to evaluate their irritant effects: A partial purification of a cardiotoxin in crude Pelagia venom was obtained using anti- Chrysaora or anti- Physalia monoclonal antibody—Sepharose columns.

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In these experiments protein bands with molecular weights of 54, 92,andwere revealed and was also reported that both crude and partially purified Pelagia venom contained active fractions against cultured chick embryo cardiocytes [ ]. The venom of Pelagia noctiluca is coues protein nature and contains peptides; it is antigenic and possesses dermonecrotic and hemolytic properties; electrophoretical analyses recognized eight different fractions, distinguished by molecular mass [ ].

The capsule fluid and the capsule wall of the nematocysts of Pelagia noctiluca were widely studied from the point of view of their protein content: As referred above, a cross-reactivity between Pelagia venom and monoclonal antibodies to Physalia and Chrysaora venoms [ ] was reported; this aspect was clinically verified by the release of histamine after exposure to Chrysaora venom by basophils from a patient who had clinical anaphylaxis after a Pelagia sting [ 96 ].

So, also clinical evidences could demonstrate the cross-reactivity between cnidairea venoms of these jellyfish; Pelagia venom has got more antigenic potential for man than several other jellyfish venoms [ 69 ]. The cytotoxic properties of Pelagia noctiluca crude venom have been experimentally assessed by short-term [ ] and long-term [ ] tests on cultured cells by trypan blue dye exclusion, neutral red, colony forming efficiency and genotoxicity assay.

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Anyhow, the venom of Pelagia noctiluca showed remarkable cytotoxicity, and killed all treated cells at highest tested concentration within two hours. The protein nature of venom [ 96 ] was further confirmed by the absence of effects on Cnldaires of treated cells [ ]. Pelagia noctiluca venom caused also an increase of ATP levels in treated cells within 1 hour of treatment and a following moderate decrease [ ]; this is a strange behaviour, because in general toxicity studies record decrease of ATP in stress-exposed cells [] and organisms [ ].

Also long term cell proliferation tests showed that the venom of Pelagia noctiluca has less effect on cells than venom of other jellyfish [ ]. The hemolytic properties of the crude venom of Pelagia noctiluca were recently assessed on fish, chicken, rabbit and human erythrocytes; results showed a significant hemolysis of chicken and rabbit erythrocytes and a good resistance of fish ones.

A satisfactory explanation of the bloom of Pelagia noctiluca in the Mediterranean, and partly in Atlantic waters has not been provided, even though several causes have been indicated as responsible of the phenomenon; a number of scientists have supposed that it could be the result of natural cyclic fluctuations, already described coyrs several species, correlated with environmental or trophic factors [ 232836414246 ].

Cousr the other hand, lack of alteration in lipid content of jellyfish during [ 57 ] and after the bloom also prevented scientists from hypothesizing about the implications of food quantity and quality in supporting the phenomenon. On the whole, outbreaks of Pelagia noctiluca can have an important ecological impact on plankton dynamics and on trophic relationships; this was seen particularly in the Adriatic Sea, where the bloom showed its maximum [ ]; as a matter of fact, events of massive occurrence of planktonic organisms could cause alterations of community structures and functioning as well as lack of biodiversity [ ].

As Pelagia noctiluca is a top predator and its feeding activity is exerted on several zooplankters, including eggs and larvae of nektonic and benthic organisms, this impact could have affected remarkably prey populations and consequently caused lower production [ ]. In this connection, from the biological and ecological point of view the chemical analyses carried out on Pelagia noctiluca specimens [ 626465 ] are important in order to evaluate the transfer of energy to high trophic levels as well as the amount of C and N available for microorganisms in consequence of the decomposition, which becomes more intense during outbreaks.

The nematocysts of Pelagia noctiluca can be found on the umbrella, oral arms and tentacles; they have been classified into five morphological types [ 6872 ] and recently they were separated into three groups [ 59 ]. It is known that the activation of nematocysts is calcium dependent and discharge is promoted by anions [ 75 ] and inhibited by lantanium and gadolinium [ 79 ].

Furthermore, the venom of this jellyfish is cytotoxic [ ] and studies performed on cell cultures, that are an efficient alternative method to the utilization of living organisms, showed also cell growth decrease after treatment. At a cellular level it was suggested that Cnidarian venoms affect the plasmalemma by binding to membrane phospholipids and increasing permeability with consequent water uptake and damage of external and intracellular membranes [ ]; the phospholipase activity of Cnidarian venoms, which affects cell membrane permeability and ion exchange, was also suggested [ — ].

Pelagia noctiluca has not caused human fatalities, but in spite of this it can be a nuisance and a health and economical problem when it appears in huge numbers during outbreaks.