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Phylllorhiza punctata von Lendenfeld, 1884 originates from Australia and Coral Triangle, but its occurrence has been reported in the Atlantic Ocean and Mediterranean Sea, so it is necessary to better understand its geographic range. Two specimens were collected in Nagasaki and Kagoshima Prefectures, Japan, and morphological and molecular studies suggest that they are P. punctata. These are the first records of the species in Japan, and it is possible that individuals have been transported to Japan by the Kuroshio Current.

Abstract Most host-parasite associations are explained by phylogenetically conservative capabilities for host utilization, and therefore parasite switches between distantly related hosts are rare. Here we report the first evidence of a parasitic spillover of the burrowing sea anemone Edwardsiella carnea from the invasive ctenophore Mnemiopsis leidyi to two scyphozoan hosts: the native Mediterranean barrel jellyfish Rhizostoma pulmo and the invasive Indo-Pacific nomad jellyfish Rhopilema nomadica, collected from the Eastern Mediterranean Sea. Edwardsiella carnea planulae found in these jellyfish were identified using molecular analyses of the mitochondrial 16S and nuclear 18S rRNA genes. Overall, 93 planulae were found on tentacles, oral arms, and inside of the gastrovascular canals of the scyphomedusae, whereas no infection was observed in co-occurring ctenophores. DNA metabarcoding approach indicated seasonal presence of Edwardsiella sp. in the Eastern Mediterranean mesozooplankton, coinciding with jellyfish blooms in the region. Our findings suggest a non-specific parasitic relationship between Edwardsiella carnea and various gelatinous hosts based on shared functionality rather than evolutionary history, potentially driven by shifts in host availability due to jellyfish blooms. This spillover raises questions about the ecological impacts of parasitism on native and invasive scyphozoan hosts and the potential role of Edwardsiella in controlling their populations.

The collection and preservation of biological material before DNA analysis is critical for inter alia biomedical research, medical diagnostics, forensics and biodiversity conservation. In this study, we evaluate an in-house formulated buffer called the Forensic DNA Laboratory-buffer (FDL-buffer) for preservation of biological material for long term at room temperature. Human saliva stored in the buffer for 8 years, human blood stored for 3 years and delicate animal tissues from the jellyfish Pelagia noctiluca comb jelly Beroe sp., stored for 4 and 6 years respectively consistently produced high-quality DNA. FDL-buffer exhibited compatibility with standard organic, salting out and spin-column extraction methods, making it versatile and applicable to a wide range of applications, including automation.

Jellyfish, microorganisms, and the marine environment collectively shape a complex ecosystem. This study aimed to analyze the microbial communities associated with five jellyfish species, exploring their composition, diversity, and relationships. Microbial diversity among the species was assessed using 16S rRNA gene sequencing and QIIME analysis. Significant differences in bacterial composition were found, with distinct dominant taxa in each species: Mycoplasmataceae (99.21%) in Aurelia coerulea, Sphingomonadaceae (22.81%) in Cassiopea andromeda, Alphaproteobacteria_unclassified (family level) (64.09%) in Chrysaora quinquecirrha, Parcubacteria_unclassified (family level) (93.11%) in Phacellophora camtschatica, and Chlamydiaceae (35.05%) and Alphaproteobacteria_unclassified (family level) (38.73%) in Rhopilema esculentum. C. andromeda showed the highest diversity, while A. coerulea exhibited the lowest. Correlations among dominant genera varied, including a positive correlation between Parcubacteria_unclassified (genus level) and Chlamydiaceae_unclassified (genus level). Genes were enriched in metabolic pathways and ABC transporters. The most abundant potential pathogens at the phylum level were Proteobacteria, Tenericutes, Chlamydiae, and Epsilonbacteraeota. The differing microbial compositions are likely influenced by species and their habitats. Interactions between jellyfish and microorganisms, as well as among microorganisms, showed interdependency or antagonism. Most microbial gene functions focused on metabolic pathways, warranting further study on the relationship between pathogenic bacteria and these pathways.

Abstract Fatty acids (FAs) are vital biomolecules crucial for determining food quality for higher trophic levels. To investigate FA transfer and turnover time in predators, we conducted a diet switch experiment using jellyfish polyps. These polyps were fed food sources including Artemia sinica nauplii and FA‐manipulated copepod Pseudodiaptomus annandalei, maintained on distinct algal diets with varied FA compositions. Our findings reveal that copepods may have a strong potential to synthesize long‐chain polyunsaturated FA to maintain biochemical homeostasis when consuming low‐quality food. Consequently, the species‐specific fatty acid composition within plankton, combined with effects of seasonal environmental fluctuations and climate change, leads to changes in the FA composition of foundational food web components. These alterations create a complex “nutrient black box” effect as they propagate up trophic levels. Our study shows that jellyfish polyps fail to accumulate EPA and DHA but display high levels of ARA compared to their zooplankton and phytoplankton food sources, suggesting a potential association with dietary EPA and DHA through an unidentified pathway. Certain FA components indicate variations in the turnover time when polyps undergo a dietary shift. Understanding the trajectory of FA metabolism across the “phytoplankton–zooplankton” interface, along with its turnover time, provides crucial insights for modeling diet estimation of components within food webs.

This is the third Cochrane Corner in the International Journal of First Aid Education, provided to you by Cochrane First Aid. Like any Cochrane Corner, it summarizes the findings of a Cochrane systematic review. It is meant to give first aid trainers, laypeople providing first aid, and guideline developers direct access to highly relevant first aid-related evidence tailored to them, which they might otherwise not have access to. Additionally, this Cochrane Corner is accompanied by a visual abstract that highlights the key findings. Cochrane First Aid aims to support Cochrane’s work by disseminating Cochrane evidence to a wider audience. To find out more, we refer you to Cochrane First Aid: the next step towards evidence-based first aid and the Cochrane First Aid website (firstaid.cochrane.org). This Cochrane Corner is based on a review that investigates the benefits and harms associated with interventions aimed at treating jellyfish stings in both adults and children. The updated review was developed by the Cochrane Pain, Palliative and Supportive Care Group and is published in the Cochrane Database of Systematic Reviews 2023, Issue 6, DOI: 10.1002/14651858.CD009688.pub3 (see www.cochranelibrary.com for information). Since Cochrane reviews are regularly updated as new evidence emerges and in response to feedback, the Cochrane Database of Systematic Reviews should be consulted for the most recent version of the review. Both the Cochrane Corner and the visual abstract were checked by Dr. Richard G McGee, the corresponding author of this Cochrane review.

Jellyfish venoms cause different reactions in human skin after exposure. The most common skin findings are linear, urticarial, and painful eruptions at the areas of tentacular contact. Delayed and recurrent rashes may also occur less commonly. We report a case of a 45-year-old female patient who developed acute pruritic rash and burning as well as dizziness on the right arm while swimming off the Island of Sicily in the Mediterranean Sea. Our patient, who had an increase in lesions from time to time in the following weeks, was diagnosed with delayed and recurrent jellyfish dermatitis according to her history and clinical findings. She was treated with systemic antihistamines, systemic steroids and topical steroids. The lesions of our patient, whose lesions did not show significant improvement with systemic antihistamines, systemic steroids, or topical steroids, improved with topical tacrolimus. Since this picture is rare in our country, we found it appropriate to present our case to emphasize that jellyfish dermatitis should be kept in mind in the differential diagnosis of patients presenting with this type of skin rash and that topical tacrolimus is effective in delayed and recurrent reactions.

Abstract Background We report a case of anaphylaxis induced by natto (fermented soybeans) allergy that occurred following dermal sensitization from a jellyfish sting. Case presentation A 49-year-old male presented to the emergency room complaining of an acute onset of erythema with pruritis that appeared while he was surfing. Given that his heart rate dropped to ~ 40 bpm without a decline in blood pressure or oxygen saturation, we suspected anaphylaxis and administered 0.5 mg of adrenaline intramuscularly. Immediately after the muscular adrenaline injection, his heart rate recovered to ~ 60–70 bpm. Conclusions The major allergen that induces natto allergy is poly(γ-glutamic acid) (PGA), which is present in its mucilage. Given that PGA is also produced by jellyfish tentacles, it can be inferred that the PGA sensitization occurred via dermal exposure to jellyfish PGA. This is an example of a food allergy induced by animal stings. As PGA is a high-molecular-weight polymer, natto allergy, despite being IgE-mediated, often presents with late-onset anaphylaxis, which typically develops half a day after digestion. PGA has a wide range of applications in pharmaceuticals, cosmetics, and foods. Patients may develop allergic symptoms and experience repeated anaphylaxis with no known cause. Therefore, it is important to obtain a detailed medical history and individually instruct patients suspected of being allergic to PGA to avoid PGA-containing products.

Abstract The growing interest in valorizing industrial by-products has led researchers to focus on exploring different sources and optimizing collagen extraction conditions over the past decade. While bovine hide, cattle bones, pork, and pig skins remain the most abundant collagen sources, there is a growing trend in the industrial utilization of collagen from non-mammalian species. This review explores alternative marine collagen sources and summarizes emerging trends in collagen recovery from marine sources, with a particular focus on environmentally friendly methods. Additionally, this review covers the colloidal structure-forming properties of marine collagens, including foam, film, gel, and emulsion formation. It also highlights the potential and important applications of marine collagen in various food products. Based on the currently reported marine sources, collagens extracted from fish, jellyfish, and sea cucumbers were found to have the highest yield and mostly comprised type-I collagen, while crustaceans and mollusks yielded lower percentages of collagen. Traditional extraction techniques isolate collagen based on acetic acid and pepsin treatment, but they come with drawbacks such as being time-consuming, causing sample destruction, and using solvents. Conversely, marine collagen extracted using conventional methods assisted with ultrasonication resulted in higher yields and strengthened the triple-stranded helical structures. Recently, an increasing number of new applications have been found in the food industry for marine collagens, such as biodegradable film-forming materials, colloid stabilizers, foaming agents, and micro-encapsulating agents. Furthermore, collagen is a modern foodstuff and is extensively used in the beverage, dairy, and meat industries to increase the stability, consistency, and elasticity of products. Graphical abstract

This study explores the moral dimensions of the planet’s challenges by examining the intersection of environmental ethics, metaphorical expressions, and geography in the context of the escalating climate crisis. The study employs the jellyfish metaphor and geographical ethics to link theoretical ethical issues with real-world societal behaviours. The study emphasizes the need to contextualize metaphors like climate change and jellyfish resilience to make them more relevant in real-world situations. This approach represents a shift in societal attitudes toward sustainable coexistence, emphasizing the use of metaphors to promote environmental consciousness and ethical action. The study aims to strongly promote ethical behaviour and environmental awareness.

In this study, three genes associated with the metabolism of Pampus argenteus, namely dehydropeptidase (dp), carboxypeptidase A (cpa), and sulfotransferase (sult), were cloned and evaluated using transcriptomics analysis, and their functions in the digestion and absorption of jellyfish were discussed. First, full-length cDNA sequences for dp1, cpa2l, and sult2 were cloned using RACE and confirmed using sequencing. The total length of the dp1 was 2 522 bp, with this transcript including an open reading frame (ORF) of 1 272 bp, a signal peptide composed of 23 amino acids, and an amide hydrolase superfamily domain. The cpa2l transcript was 1 421 bp long and encoded a 1 260 bp ORF. This protein consisted of a signal peptide of 16 amino acids and was characterized by a typical M14 metal carboxypeptidase family domain. sult2 was 1 834 bp in length, producing an ORF of 714 bp, which included a typical sulfatase domain. In addition, homology evaluations of these three P. argenteus genes revealed that they were most similar to the bluefin tuna (Thunnus maccoyii), and phylogenetic tree analysis showed that dp1, cpa2l, and sult2 were all closely related to their corresponding genes from T. maccoyii. RT-qPCR was then used to evaluate the expression levels of these three genes in different tissues and the changes in expression patterns in response to jellyfish ingestion. These experiments revealed that dp1 expression was naturally the highest in the liver (P < 0.05) and significantly increased in the brain, gills (P < 0.01), midgut, and kidney (P < 0.05), but significantly decreased in the muscle (P < 0.05) when compared to that in the non-feeding control. cpa2l expression was highest in the middle intestine in the non-jellyfish feeding group and the kidney in the jellyfish feeding group (P < 0.05) and was shown to be significantly increased in the liver (P < 0.01) but significantly decreased in the midgut and muscle (P < 0.01) when compared to that in the non-feeding group. sult2 expression was highest in the liver (P < 0.05) and significantly increased in the midgut, brain, gill, liver, and kidney in the feeding group compared to that in the non-feeding group (P < 0.05). Taken together, these results suggest that dp1, cpa2l, and sult2 play important roles in nutrient digestion, absorption, and metabolism in P. argenteus, especially in response to jellyfish feeding. In addition, the results of the tissue expression patterns for each of these genes following jellyfish ingestion suggest that dp1 is primarily involved in the regulation of digestion, absorption, and nutrient deposition; cpa2l is involved in the regulation of nutrient metabolism in the liver; and sult2 may play an important role in the overall process of digestion, absorption, and metabolism.

This study aimed to develop bioactive protein hydrolysates from low-value edible jellyfish obtained from local fisheries using enzymatic hydrolysis. Fresh white jellyfish were hydrolyzed using several commercial proteases, including alcalase (WJH-Al), flavourzyme (WJH-Fl), and papain (WJH-Pa). The antioxidant, immunomodulatory, and anticancer activities of these white jellyfish hydrolysates (WJH) were investigated. The results demonstrated that the crude WJH exhibited strong antioxidant properties, including DPPH, ABTS, and hydroxyl radical scavenging activities, as well as ferric-reducing antioxidant power. Additionally, the hydrolysates showed notable immunomodulatory activity. However, all WJH samples displayed relatively low ability to inhibit HepG2 cell proliferation at the tested concentrations. Among the hydrolysates, WJH-Pa demonstrated the highest antioxidant and immunomodulatory activities and was therefore selected for further bioactive peptide isolation and characterization. Ultrafiltration membranes with three molecular weight (MW) cut-offs (1, 3, 10 kDa) were used for peptide fractionation from WJH-Pa. Six potential peptides were identified with the MW range of 1049–1292 Da, comprising 9–12 residues, which exhibited strong antioxidant and immunomodulatory activities.

Abstract Fram Strait, the gateway between the Arctic and Atlantic Oceans, is undergoing major climate change‐induced physical and biological transformations. In particular, rapid warming and ongoing “Atlantification” are driving species range shifts and altering food web structures in the Arctic. Understanding and predicting the consequences of these processes on future ecosystems requires detailed assessments of local and pelagic biodiversity. Gelatinous zooplankton (GZP) is an important component of pelagic communities, and recent evidence indicates that such communities are undergoing major changes in the Fram Strait. However, as sampling GZP is challenging, they are regularly underestimated in biodiversity, distribution, and abundance. To overcome this and address existing ecological knowledge gaps, we investigated patterns of pelagic metazoan diversity in Fram Strait using environmental DNA (eDNA) metabarcoding of the cytochrome c oxidase I (COI) gene. We successfully detected a broad range of taxa from the marine metazoan and GZP communities across sampling locations and ocean depth zones. We demonstrate the vertical structuring of diversity and elucidate relationships between taxa and water mass indicators, such as salinity and temperature. Furthermore, when comparing eDNA data with net and video transect data for GZP at the same period and location, we found that eDNA uncovered a higher number of taxa, including several that were not detected by the other methods. This study is a contribution to the formation of baseline Arctic GZP biodiversity datasets, as well as future research on changing marine metazoan biodiversity and community composition.

Many metazoans contain molecules capable of fluorescence, the absorption and re-emission of light. Since the anatomical distribution, or patterning, of these molecules is variable across taxa, patterns of fluorescence may serve as a powerful diagnostic tool in taxonomy and ecology. However, species-specific fluorescence patterns among marine invertebrates are poorly understood. Here, we show that hydrozoans have diverse fluorescence patterns, which may result from molecules that are produced intrinsically or obtained from dietary sources. We surveyed hydrozoans including siphonophores, hydromedusae, and hydroids across 5 orders from pelagic and benthic marine environments in Bocas del Toro, Panama. Our findings show that fluorescence patterns are highly prevalent and may vary across hydrozoan species and throughout development. Most of the examined hydrozoan taxa exhibited some form of fluorescence, with variation observed between life stages and body parts. Fluorescence was documented in 88% of hydromedusae (Leptothecata, Anthoathecata, Limnomedusae and Narcomedusae), 50% of hydroid, and 75% of siphonophore taxa that were observed in this study. Our results illustrate how fluorescence patterns may serve as a useful diagnostic tool to explore marine biodiversity, highlighting the need for further documentation of fluorescence patterns across marine diversity and research into the molecules that underlie this phenomenon.

Atherosclerosis, a noncommunicable disease caused by cholesterol plaque, can cause chronic diseases. The antiplatelet medicines used in its treatment can cause complications. Marine collagen peptides can be used as a natural atherosclerosis remedy. The present study investigated the preparation and characterization of hydrolyzed collagen (HC) from jellyfish and its conjugation with black jelly mushroom extract (BJME). Their cytotoxicity and ability to prevent cholesterol-induced endothelial cell injury were also examined. HC was prepared using Alcalase or papain hydrolysis (0.2–0.4 units/g of dry matter (DM)). Higher yield, degree of hydrolysis, and antioxidant activities (AAs) were found in the HC obtained from Alcalase, especially at 0.4 units/g DM (A-0.4), compared to other processes (p < 0.05). Thus, A-0.4 was further conjugated with BJME (1–4%, w/w of HC). The HC-2%BJME conjugate showed the highest surface hydrophobicity and AAs compared to other samples. The FTIR spectra and size distribution also confirmed the conjugation between HC and BJME. When EA.hy926 endothelial cells were treated with HC or HC-2%BJME (25–1000 µg/mL), HC-2%BJME had no cytotoxicity, whereas HC at 1000 µg/mL induced cytotoxicity (p < 0.05). Both samples also exhibited protective ability against cholesterol-induced apoptosis and VE-cadherin downregulation of cells. Therefore, HC and conjugate could be natural agents for preventing atherosclerosis.

In recent years, there have been frequent jellyfish outbreaks in Chinese coastal waters, significantly impacting the structure, functionality, safety, and economy of nuclear power plant cooling water intake and nearby ecosystems. Therefore, this study focuses on jellyfish outbreaks in Chinese coastal waters, particularly near the Shandong Peninsula. By analyzing jellyfish abundance data, a Generalized Additive Model integrating environmental factors reveals that temperature and salinity greatly influence jellyfish density. The results show variations in jellyfish density among years, with higher densities in coastal areas. The model explains 42.2% of the variance, highlighting the positive correlation between temperature (20–26 °C) and jellyfish density, as well as the impact of salinity (27.5–29‰). Additionally, ocean currents play a significant role in nearshore jellyfish aggregation, with a correlation between ocean currents and site coordinates. This study aims to investigate the relationship between jellyfish blooms and environmental factors. The results obtained from the study provide data support for the prevention and control of blockages in nuclear power plant cooling systems, and provide a data basis for the implementation of monitoring measures in nuclear power plants.

ABSTRACTBlooms of gelatinous zooplankton, an important source of protein-rich biomass in coastal waters, often collapse rapidly, releasing large amounts of labile detrital organic matter (OM) into the surrounding water. Although these blooms have the potential to cause major perturbations in the marine ecosystem, their effects on the microbial community and hence on the biogeochemical cycles have yet to be elucidated. We conducted microcosm experiments simulating the scenario experienced by coastal bacterial communities after the decay of a ctenophore (Mnemiopsis leidyi) bloom in the northern Adriatic Sea. Within 24 h, a rapid response of bacterial communities to the M. leidyi OM was observed, characterized by elevated bacterial biomass production and respiration rates. However, compared to our previous microcosm study of jellyfish (Aurelia aurita s.l.), M. leidyi OM degradation was characterized by significantly lower bacterial growth efficiency, meaning that the carbon stored in the OM was mostly respired. Combined metagenomic and metaproteomic analysis indicated that the degradation activity was mainly performed by Pseudoalteromonas, producing a large amount of proteolytic extracellular enzymes and exhibiting high metabolic activity. Interestingly, the reconstructed metagenome-assembled genome (MAG) of Pseudoalteromonas phenolica was almost identical (average nucleotide identity >99%) to the MAG previously reconstructed in our A. aurita microcosm study, despite the fundamental genetic and biochemical differences of the two gelatinous zooplankton species. Taken together, our data suggest that blooms of different gelatinous zooplankton are likely triggering a consistent response from natural bacterial communities, with specific bacterial lineages driving the remineralization of the gelatinous OM.IMPORTANCEJellyfish blooms are increasingly becoming a recurring seasonal event in marine ecosystems, characterized by a rapid build-up of gelatinous biomass that collapses rapidly. Although these blooms have the potential to cause major perturbations, their impact on marine microbial communities is largely unknown. We conducted an incubation experiment simulating a bloom of the ctenophore Mnemiopsis leidyi in the Northern Adriatic, where we investigated the bacterial response to the gelatinous biomass. We found that the bacterial communities actively degraded the gelatinous organic matter, and overall showed a striking similarity to the dynamics previously observed after a simulated bloom of the jellyfish Aurelia aurita s.l. In both cases, we found that a single bacterial species, Pseudoalteromonas phenolica, was responsible for most of the degradation activity. This suggests that blooms of different jellyfish are likely to trigger a consistent response from natural bacterial communities, with specific bacterial species driving the remineralization of gelatinous biomass.

ABSTRACTBased on a systematic literature search, I recently reviewed learning in the phylum Cnidaria, animals possessing a nerve net as a nervous system but no centralized brain. I found abundant evidence of non-associative learning, both habituation and sensitization, but only sparse evidence of associative learning. Only one well-controlled study on classical conditioning in sea anemones provided firm evidence, and no studies firmly supported operant conditioning in Cnidaria, although several provided suggestive evidence. More research on associative learning in this phylum is needed.

We identified a new human voltage-gated potassium channel blocker, NnK-1, in the jellyfish Nemopilema nomurai based on its genomic information. The gene sequence encoding NnK-1 contains 5408 base pairs, with five introns and six exons. The coding sequence of the NnK-1 precursor is 894 nucleotides long and encodes 297 amino acids containing five presumptive ShK-like peptides. An electrophysiological assay demonstrated that the fifth peptide, NnK-1, which was chemically synthesized, is an effective blocker of hKv1.3, hKv1.4, and hKv1.5. Multiple-sequence alignment with cnidarian Shk-like peptides, which have Kv1.3-blocking activity, revealed that three residues (3Asp, 25Lys, and 34Thr) of NnK-1, together with six cysteine residues, were conserved. Therefore, we hypothesized that these three residues are crucial for the binding of the toxin to voltage-gated potassium channels. This notion was confirmed by an electrophysiological assay with a synthetic peptide (NnK-1 mu) where these three peptides were substituted with 3Glu, 25Arg, and 34Met. In conclusion, we successfully identified and characterized a new voltage-gated potassium channel blocker in jellyfish that interacts with three different voltage-gated potassium channels. A peptide that interacts with multiple voltage-gated potassium channels has many therapeutic applications in various physiological and pathophysiological contexts.

The escalation of jellyfish stings has drawn attention to severe skin reactions, underscoring the necessity for novel treatments. This investigation assesses the potential of hydroxybenzoic acid derivatives, specifically protocatechuic acid (PCA) and gentisic acid (DHB), for alleviating Nemopilema nomurai Nematocyst Venom (NnNV)-induced injuries. By employing an in vivo mouse model, the study delves into the therapeutic efficacy of these compounds. Through a combination of ELISA and Western blot analyses, histological examinations, and molecular assays, the study scrutinizes the inflammatory response, assesses skin damage and repair mechanisms, and investigates the compounds’ ability to counteract venom effects. Our findings indicate that PCA and DHB significantly mitigate inflammation by modulating critical cytokines and pathways, altering collagen ratios through topical application, and enhancing VEGF and bFGF levels. Furthermore, both compounds demonstrate potential in neutralizing NnNV toxicity by inhibiting metalloproteinases and phospholipase-A2, showcasing the viability of small-molecule compounds in managing toxin-induced injuries.

Due to its excellent biocompatibility and ease of biodegradation, jellyfish gelatin has gained attention as a hydrogel. However, hydrogel produced from jellyfish gelatin has not yet been sufficiently characterized. Therefore, this research aims to produce a jellyfish gelatin-based hydrogel. The gelatin produced from desalted jellyfish by-products varied with the part of the specimen and extraction time. Hydrogels with gelatin: glutaraldehyde ratios of 10:0.25, 10:0.50, and 10:1.00 (v/v) were characterized, and their cefazolin release ability was determined. The optimal conditions for gelatin extraction and chosen for the development of jellyfish hydrogels (JGel) included the use of the umbrella part of desalted jellyfish by-products extracted for 24 h (WU24), which yielded the highest gel strength (460.02 g), viscosity (24.45 cP), gelling temperature (12.70 °C), and melting temperature (22.48 °C). The quantities of collagen alpha−1(XXVIII) chain A, collagen alpha−1(XXI) chain, and collagen alpha−2(IX) chain in WU24 may influence its gel properties. Increasing the glutaraldehyde content in JGel increased the gel fraction by decreasing the space between the protein chains and gel swelling, as glutaraldehyde binds with lateral amino acid residues and produces a stronger network. At 8 h, more than 80% of the cefazolin in JGel (10:0.25) was released, which was higher than that released from bovine hydrogel (52.81%) and fish hydrogel (54.04%). This research is the first report focused on the production of JGel using glutaraldehyde as a cross-linking agent.

The abundance of gelatinous organisms, such as salps and jellyfish, in the Adriatic Sea has significantly increased over the past decade. Environmental factors play a key role in driving this shift in abundance through rising temperatures and a consequent decrease in oxygen levels in the water, for which jellyfish have higher tolerance levels. Additionally, fisheries may contribute to the proliferation of jellyfish by diminishing their natural predators and food competitors. Pelagic trawl catch data from 2015 to 2023 acquired during MEDIAS acoustic surveys in the western Adriatic Sea were reviewed to extract information concerning the abundance and distribution of salps and jellyfish. These data were subsequently analyzed and compared with satellite environmental information to identify potential correlations. When considering environmental information related to the month of the survey, the results show two significant relationships: one between the abundance of Aequorea aequorea and average salinity and another one between the abundance of Rhizostoma pulmo and bottom temperature. Furthermore, when considering environmental data from the month preceding the survey, a relationship between the overall abundance of gelatinous organisms, salps and jellyfish together, and surface temperature was identified. Additionally, an analysis was conducted on specific hauls that almost exclusively yielded jellyfish, with the aim of identifying their echo traces. Although it was not possible to allocate one jellyfish species to a specific echo trace due to the frequent co-occurrence of more than one species, a general indication of typical backscatter for these species, with a higher response at 70 kHz, was consistently observed in all cases examined.

In 1980, reports of deep-sea jellyfish blooms in Norwegian fjords led researchers to investigate the problem. The helmet jellyfish, Periphylla periphylla, has since migrated far north into Arctic waters. This paper examines what happened when the jellyfish blooms were noticed in 1980 from a historical and ethnographic perspective. It traces four research projects and business ideas that proposed solutions to the jellyfish problem and asks how they are representative of the ways in which humans meet the challenges of anthropogenic climate change. The paper concludes that the jellyfish problem was met with a “techno-fix” attitude that sought to “turn a problem into a resource”, which eventually leads to what Julia Livingston has termed “self-devouring growth”. In a final outlook, the article asks how we can engage with questions of conservation from a humanities perspective and concludes that the jellyfish story can help us to ask questions about “conservation for whom”.

In this study, microporous activated carbon was produced from jellyfish-based biomass to capture carbon dioxide (CO2), toward addressing one of the biggest modern problems. The surface functional groups and porosity of activated carbon derived from jellyfish were investigated according to the activation conditions. It was confirmed that the jellyfish-based porous carbon prepared by NaOH activation comprised many micropores that facilitated CO2 adsorption under the influence of Na and P present in the microstructure of the jellyfish. In addition, the JFBC-based activated carbon had surface functional groups such as nitrogen, calcium, and magnesium, which facilitated CO2. The jellyfish-based activated carbon shows very excellent CO2 adsorption capacity (9.52 mmol/g and 5.18 mmol/g at 273 K and 298 K, respectively) compared to activated carbon prepared from porous carbon-based adsorbents for CO2 capture. This performance is attributed to the microstructure and various heteroatoms of the jellyfish biochar. Therefore, this study may provide insight into new biomass with competitive adsorption power and without requiring complicated manufacturing steps.

In recent years, large numbers of jellyfish have congregated in marine areas, leading to a decline in other plankton and fisheries. Jellyfish themselves have a certain toxicity and aggression, which have a serious impact on the safety of human life. In order to detect the quantity and distribution of underwater jellyfish, and to be more proactive in the prevention and control of Aurelia outbreaks, this study proposed a method for in-situ detection of underwater jellyfish based on the improved Faster R-CNN network model. Firstly, the real data sets of three species of jellyfish in the Qinhuangdao sea area were established by using underwater high-definition camera. The Multi Scale Retinex with Colour Restoration (MSRCR) algorithm was used to improve the brightness and contrast of the underwater images. Secondly, the residual network Resnet50 was integrated into the backbone network for better feature extraction; then the semi-precision floating-point number FP16 was added to improve the training speed. Finally, comparative experiments were conducted to verify the improved network. The F1 value, the P-R curve, the Loss curve and the AP value of the three detection models were evaluated and compared. The experimental results showed that compared to Vgg16 network and YOLO V3 network, the training speed was improved from 1.85bit/s to 7.35bit/s, and the accuracy was also improved to over 0.98. The experimental results were good, and the research results provided a more accurate and faster method for the in-situ detection of underwater jellyfish.

Underwater biological surveys have been conducted around the Antarctic continent for several decades, and our knowledge of the species present in the shallow waters (

Abstract Background While the majority of reported cases of jellyfish envenomation are self-limited with few lasting complications, a few can cause life-threatening and debilitating illnesses. We present the case of a 15-year-old male who had an unusual presentation of a jellyfish sting that led to acute compartment syndrome. Case presentation A 15-year-old Lebanese (Arab) boy was stung by a jellyfish, which led to acute compartment syndrome in the left arm. Decompression fasciotomy and local application of diluted nitroglycerin helped to relieve the ulnar and radial artery spasms. The patient was left with shoulder and elbow pain and elbow flexion weakness, which improved after physiotherapy over a period of 6 weeks. Conclusions Current therapy recommendations for acute compartment syndrome following jellyfish stings are mainly based on case reports. Urgent fasciotomy and local application of nitroglycerin have been demonstrated to be helpful in severe jellyfish stings associated with acute compartment syndrome.

The Red Sea is a rich ecosystem with thousands of species containing a variety of bioactive compounds that have potential pharmacological applications. This study will highlight the potential importance of sea urchins and jellyfish extracts. The gas chromatography-mass spectrometry (GC–MS) revealed many phenolic compounds in the extracts of the sea urchin (Diadema savignyi) and jellyfish (Aurelia aurita). The extracts were also tested for their potential radical scavenging activity as well as their safety and toxicity in vitro and in vivo. Both extracts showed significant total antioxidant capacity (P-value

Due to their ubiquity and potential risks, microplastics (MPs) and nanoplastics (NPs) are concerning environmental issues. Yet there are still significant knowledge gaps in understanding the tissue-specific accumulation and dynamic change of MPs and NPs in the aquatic organism and how these micro/nano-scale emerging contaminants interact with other environmental pollutants such as persistent organic pollutants (POPs). Here, in vivo imaging systems (IVIS), radioisotope tracing, and histological staining were innovatively used to reveal the fate and toxicity of fluorescently-labeled MPs/NPs and 14C-labeled 2,4,4′-trichlorobiphenyl (PCB28) in edible jellyfish Rhopilema esculentum. These contaminants' ingestion, biological effects, and interactions were visualized at cellular, tissue, and whole-body multidimensional levels. Both MPs and NPs were shown to be preferentially accumulated in the mouthlets of oral arms, and most ingested MPs/NPs were present in the extracellular environment instead of being internalized into the mesoglea. Moreover, the presence of MPs or NPs in the seawater significantly inhibited the bioaccumulation of PCB28 in the jellyfish tissue, thus alleviating physiological alteration, gastric damage, and apoptosis caused by PCB28. This study provides a multi-dimensional visualization strategy to display the distribution and biological effects of typical pollutants in marine organisms and offers new insights for understanding the impacts of MPs/NPs and POPs on marine ecosystems.

The rhizostomatid scyphozoan Rhopilema nomadica is one of the most notorious marine invasive species established in the eastern Mediterranean Sea. Using seven microsatellite loci, here, we examined the population genetic structures on 587 individual tissue samples collected from 21 sites along the Mediterranean coast of Israel over a period of 16 years. The results indicate unique microsatellite landscapes for all samples, which belong to a single unstructured population. The >20 alleles found in most loci, low fixation index (F) values (average 0.106), and high heterozygosity (average 0.667) suggest random or assortative mating. Additionally, the low overall differentiation (Fst) values (0.043) and pairwise Fst values between the samples collected in different years indicated gene flow and random mating over the years, potentially due to the long-lasting podocytes, scyphistomae, and adults causing a population overlap between the sampled months/years. Likewise, analyses were conducted between seasons, sites, and early/intermediate/late periods of collecting years. These results support the previous analyses performed on the mitochondrial gene cytochrome oxidase subunit I (COI) sequences, altogether indicating a highly polymorphic single unstructured R. nomadica population in the Levant, possibly backed by independent introductions. The results hint to the existence of highly functional connectivity with a genetically highly diverse source population.

Ctenophores, hydroid jellyfish, appendicularians, salpas, and the pteropoda mollusk Clione limacina, conditionally combined into the group of “jellyfish”, are found in the food of all Pacific salmon — chum salmon, pink salmon, sockeye salmon, coho salmon and chinook salmon, but only in chum salmon their share is most significant, which is shown both absolute criteria (CHIN-private index of gastric filling of certain species and groups of jelly beans) and relative (share of jelly in the total INJ-general index of stomach filling). In food, chum salmon were present in 45.0 % of samples, pink salmon — 11.0 %, sockeye salmon — 7.0 %, coho salmon — 3.3 %, chinook salmon — 1.1 %. Chum salmon is well adapted to nutrition with jelly, because. has a stomach many times larger than that of other salmon, and in the diet of gelatinous it takes first place among them. Thus, in the event of a shortage of the main food (crustaceans, fish, squid), the chum salmon, due to the ability to consume and assimilate low-calorie food in large volumes, receives additional benefits in competitive relations with salmon and other pelagic fish.

Knowledge of life histories is crucial for understanding ecological and evolutionary processes, but for many hydrozoan species only incomplete life cycles have been described due to challenges in linking hydromedusae with their polyp stages. Using a combination of DNA barcoding, morphology, and ecological information, we describe for the first time the polyp stage of Halopsis ocellata Agassiz, 1865 and re-describe that of Mitrocomella polydiademata (Romanes, 1876). Campanulinid hydroids referable to Lafoeina tenuis Sars, 1874 and collected in the same biogeographic region as the type locality of this species are shown to be the polyp stage of these two mitrocomid hydromedusae. The nominal species L. tenuis thus is a species complex that includes the polyp stage of medusae belonging to at least two genera currently placed in a different family. Consistent morphological and ecological differences were found between the polyps linked to each of these two hydromedusae, but molecular results suggest that yet other species may have morphologically similar hydroids. Polyps morphologically identified to L. tenuis are therefore better referred to as Lafoeina tenuis-type until further associations are resolved, particularly when occurring outside of the area of distribution of H. ocellata and M. polydiademata. Molecular identification integrated with traditional taxonomy is confirmed as an effective approach to link inconspicuous stages of marine invertebrates with hitherto unknown life cycles, especially in often-overlooked taxa. Disentangling the relationships between L. tenuis, H. ocellata, and M. polydiademata lays the ground for future research aimed at resolving the taxonomy and systematics of the enigmatic families Mitrocomidae and Campanulinidae.

Abstract Despite their seemingly watery constitution, jellyfish are eaten by a diverse range of predators. However, while the role of jellyfish in marine food webs is gaining attention, the nutritional value of these gelatinous organisms and how it varies remain poorly understood. In this study, we aimed to connect jellyfish food web biology and nutrition by determining the relationship between jellyfish size, diet, and nutritional quality. We measured stable isotope (SI) and fatty acid (FA) profiles of particulate organic matter (POM), plankton size classes, and gelatinous zooplankton collected from a coastal site in British Columbia, Canada, in July and September 2019. Gelatinous zooplankton comprised 152 Aurelia labiata collected across both months (bell diameters = 19–225 mm), and 2 Aequorea victoria and approximately 30 Pleurobrachia bachei collected in July for comparison. According to FA trophic markers and chlorophyll a concentrations, the POM was a mix of phytoplankton, microzooplankton, bacteria, and detritus. According to δ15N, POM was ~1 trophic level lower than plankton. All gelatinous zooplankton had low FA content (5–6 μg/mg dry mass) compared with zooplankton (43–65 μg/mg dry mass). A Bayesian mixing model (MixSIAR) was used to assess the contributions of POM and plankton to A. labiata diet, which demonstrated a size‐based shift from 40% plankton at 19 mm to 70%–75% at 225 mm. Similarly, both δ13C and δ15N increased with size and A. labiata of 19 mm were ~1 trophic level lower than A. labiata of 225 mm. We also documented size‐based changes in nutritional quality of A. labiata, where C:N decreased with A. labiata size, and essential FAs arachidonic acid (ARA) and docosahexaenoic acid (DHA) increased with size while eicosapentaenoic acid (EPA) did not change. A. labiata were elevated in ARA compared with other zooplankton, ranging from 1% to 9%. The changes in C:N and DHA of A. labiata with size mirrored the changes in their diet, but changes in ARA and EPA did not. Overall, these findings emphasize the importance of considering jellyfish size and taxonomy when evaluating nutritional pathways through jellyfish in marine food webs, and support that diet is one important driver of jellyfish biochemical composition.

IntroductionThe jellyfish Cassiopea has a conspicuous lifestyle, positioning itself upside-down on sediments in shallow waters thereby exposing its photosynthetic endosymbionts (Symbiodiniaceae) to light. Several studies have shown how the photosymbionts benefit the jellyfish host in terms of nutrition and O2 availability, but little is known about the internal physico-chemical microenvironment of Cassiopea during light–dark periods.MethodsHere, we used fiber-optic sensors to investigate how light is modulated at the water-tissue interface of Cassiopea sp. and how light is scattered inside host tissue. We additionally used electrochemical and fiber-optic microsensors to investigate the dynamics of O2 and pH in response to changes in the light availability in intact living specimens of Cassiopea sp.Results and discussionMapping of photon scalar irradiance revealed a distinct spatial heterogeneity over different anatomical structures of the host, where oral arms and the manubrium had overall higher light availability, while shaded parts underneath the oral arms and the bell had less light available. White host pigmentation, especially in the bell tissue, showed higher light availability relative to similar bell tissue without white pigmentation. Microprofiles of scalar irradiance into white pigmented bell tissue showed intense light scattering and enhanced light penetration, while light was rapidly attenuated over the upper 0.5 mm in tissue with symbionts only. Depth profiles of O2 concentration into bell tissue of live jellyfish showed increasing concentration with depth into the mesoglea, with no apparent saturation point during light periods. O2 was slowly depleted in the mesoglea in darkness, and O2 concentration remained higher than ambient water in large (> 6 cm diameter) individuals, even after 50 min in darkness. Light–dark shifts in large medusae showed that the mesoglea slowly turns from a net sink during photoperiods into a net source of O2 during darkness. In contrast, small medusae showed a more dramatic change in O2 concentration, with rapid O2 buildup/consumption in response to light–dark shifts; in a manner similar to corals. These effects on O2 production/consumption were also reflected in moderate pH fluctuations within the mesoglea. The mesoglea thus buffers O2 and pH dynamics during dark-periods.

Porpita porpita occurs in the tropical and sub-tropical waters of the Pacific, Atlantic, and Indian Oceans, and the mass numbers of stranded colonies seem to be increasing. Although its presence in Indian waters is minimal, this is the first record ever made of P. porpita in Visakhapatnam coastal waters. The present study provided a detailed description of the species and its global distribution. Further, the perceived increase in gelatinous zooplankton blooms in the observed area indicates that jellyfish can negatively affect fisheries because they compete with zooplanktivorous fish, prey upon fish eggs and larvae, and indirectly compete with higher trophic levels by reducing the plankton available to planktivores. Conversely, jellyfishes also play a vital role in regulating global marine plankton food webs, spatio-temporal dynamics, and biomass, which is a role that has been generally neglected so far.

Crude polysaccharides were extracted from the white jellyfish (Lobonema smithii) using water extraction and fractionated using ion-exchange chromatography to obtain three different fractions (JF1, JF2, and JF3). The chemical characteristics of four polysaccharides were investigated, along with their anti-inflammatory effect in LPS-stimulated RAW264.7 cells. All samples mainly consisted of neutral sugars with minor contents of proteins and sulphates in various proportions. Glucose, galactose, and mannose were the main constituents of the monosaccharides. The molecular weights of the crude polysaccharides and the JF1, JF2, and JF3 fractions were 865.0, 477.6, 524.1, and 293.0 kDa, respectively. All polysaccharides were able to decrease NO production, especially JF3, which showed inhibitory activity. JF3 effectively suppressed iNOS, COX-2, IL-1β, IL-6, and TNF-α expression, while IL-10 expression was induced. JF3 could inhibit phosphorylated ERK, JNK, p38, and NF-κB p65. Furthermore, flow cytometry showed the impact of JF3 on inhibiting CD11b and CD40 expression. These results suggest that JF3 could inhibit NF-κB and MAPK-related inflammatory pathways. The structural characterisation revealed that (1→3)-linked glucopyranosyl, (1→3,6)-linked galactopyranosyl, and (1→3,6)-linked glucopyranosyl residues comprised the main backbone of JF3. Therefore, L. smithii polysaccharides exhibit good anti-inflammatory activity and could thus be applied as an alternative therapeutic agent against inflammation.

Collagen has been considered a key treatment option in preventing damage to the articular cartilage over time and supporting the healing process, following the onset of osteoarthritis (OA). This study aimed to investigate the effect of collagen fermented from jellyfish (FJC) by Bacillus subtilis natto on anterior cruciate ligament transection with medial meniscectomy (ACLT + MMx)-induced knee OA in high-fat diet (HFD)-induced obesity in rats. The male Sprague–Dawley rats were fed an HFD for 6 weeks before ACLT + MMx surgery, after which they were administered a daily oral gavage of saline (control, OA, and OBOA), either with FJC (20 mg/kg, 40 mg/kg, and 100 mg/kg body weight) or glucosamine sulfate as a positive control (GS; 200 mg/kg body weight) for 6 weeks. Treatment with FJC decreased the fat weight, triglyceride, and total cholesterol levels in obese rats. Additionally, FJC downregulated the expression of some proinflammatory cytokines, including tumor necrosis factor-α, cyclooxygenase-2, and nitric oxide; suppressed leptin and adiponectin expression; and attenuated cartilage degradation. It also decreased the activities of matrix metalloproteinase (MMP)-1 and MMP-3. These results demonstrated that FJC showed a protective effect on articular cartilage and also suppressed the degradation of cartilage in an animal OA model, suggesting its potential efficacy as a promising candidate for OA treatment.

The light-dependent zooxanthellate jellyfish Cassiopea sp. (the upside-down jellyfish) is invasive/exotic in many shallow and clear marine habitats, where the jellyfish might be exposed to high levels of ultraviolet radiation (UVR). Compared to other reef organisms, the sensitivity/resilience of the semi-transparent jellyfish to UVR exposure is overlooked. Therefore, we experimentally investigated the metabolic and physiological responses of Cassiopea sp. from the Red Sea to natural levels of underwater UVR following 16 days of exposure to three light treatments: 1) control group with only photosynthetically active radiation (PAR), 2) PAR+UV-B, and 3) PAR+UV-B+UV-A. While jellyfish body mass increased (by 40%) significantly in the control group, it did not increase in either of the UV treatments. However, both UV-exposed jellyfish had higher (98% to 120%) mitochondrial electron transport system (ETS) activity than the control group. Therefore, the results indicate elevated aerobic respiration rates in UV-exposed jellyfish (i.e., reflecting a higher energy cost of UVR exposure). Neither the lactate dehydrogenase (LDH) activity nor the available energy (Ea) exhibited different levels among UVR treatments compared to the control group. In contrast, pyruvate kinase activity was significantly lower (by 46%) in all UV-exposed jellyfish compared to the control group. Unchanged Ea and LDH activity combined with higher ETS activity indicates a high aerobic capacity of jellyfish, which might explain their ability to cope with UVR exposure-induced higher energy demands without inducing the onset of anaerobiosis. The results indicated that UV-A does not amplify or modulate jellyfish physiology and growth under UV-B exposure. In conclusion, the findings suggest that the jellyfish is more resilient (i.e., in terms of survival) to UVR than other cnidarians. This study on Cassiopea is the first to address its metabolic and physiological responses to UVR. Therefore, it could be used as a framework for further studies aiming to better understand jellyfish physiology.

Patterns in biology can be considered as predetermined or arising from a self-organizing instability. Variability in the pattern can, thus, be interpreted as a trace of instability, growing out from noise. Studying this variability can, thus, hint toward an underlying morphogenetic mechanism. Here, we present the variability of the gastrovascular system of the jellyfish Aurelia. In this variability emerges a typical biased reconnection between canals and time-correlated reconnections. Both phenomena can be interpreted as traces of mechanistic effects, the swimming contractions on the tissue surrounding the gastrovascular canals, and the mean fluid pressure inside them. This reveals the gastrovascular network as a model system to study the morphogenesis of circulation networks and the morphogenetic mechanisms at play.

The jellyfish Cassiopea xamachana and C. frondosa co-occur within some habitats in the Florida Keys, but the frequency with which this occurs is low. It is hypothesized that the symbiosis with different dinoflagellates in the Symbiodiniaceae is the reason: the medusae of C. xamachana contain heat-resistant Symbiodinium microadriaticum (ITS-type A1), whereas C. frondosa has heat-sensitive Breviolum sp. (ITS-type B19). Cohabitation occurs at depths of about 3–4 m in Florida Bay, where the water is on average 0.36 °C cooler, or up to 1.1 °C cooler per day. C. frondosa tends not to be found in the warmer and shallower (C. frondosa medusae have a greater density of symbionts and appear darker in color compared to large C. xamachana. However, the number of symbionts per amebocyte are about the same, which implies that the large C. frondosa has more amebocytes than the large C. xamachana. The photosynthetic rate is similar in small medusae, but a greater reduction in photosynthesis is observed in the larger medusae of C. xamachana compared to those of C. frondosa. Medusae of C. xamachana have greater pulse rates than medusae of C. frondosa, suggestive of a greater metabolic demand. The differences in life history traits of the two species were also investigated to understand the factors that contribute to observed differences in habitat selection. The larvae of C. xamachana require lower concentrations of inducer to settle/metamorphose, and they readily settle on mangrove leaves, submerged rock, and sand compared to the larvae of C. frondosa. The asexual buds of C. xamachana are of a uniform and similar shape as compared to the variably sized and shaped buds of C. frondosa. The larger polyps of C. frondosa can have more than one attachment site compared to the single holdfast of C. xamachana. This appears to be an example of niche diversification that is likely influenced by the symbiont, with the ecological generalist and heat-resistant S. microadriaticum thriving in C. xamachana in a wider range of habitats as compared to the heat-sensitive symbiont Breviolum sp., which is only found in C. frondosa in the cooler and deeper waters.

Abstract Biofilms are responsible for about considerable amounts of cases of bacterial infections in humans. They are considered a major threat to transplant and chronic wounds patients due to their highly resistant nature against antibacterial materials and due to the limited types of techniques that can be applied to remove them. Here we demonstrate a successful in-situ bio-assisted synthesis of dual functionality nanoparticles composed of Silver and Gold. This is done using a jellyfish-based scaffold, an antibacterial material as the templating host in the synthesis. We further explore the scaffold’s antibacterial and photothermal properties against various gram-negative and positive model bacteria with and without photo-induced heating at the Near-IR regime. We show that when the scaffold is loaded with these bimetallic nanoparticles, it exhibits dual functionality: Its photothermal capabilities help to disrupt and remove bacterial colonies and mature biofilms, and its antibacterial properties prevent the regrowth of new biofilms. Graphical Abstract

Mucus secretion provides an interface with unique and multifunctional properties between the epithelial cells of many aquatic organisms and their surrounding environment. Indeed, mucus is involved in various essential biological processes including feeding, reproduction, osmoregulation, competition for space, defense against pathogens, xenobiotics, and a multitude of environmental stressors. The ability to produce a functional mucus layer is an important evolutionary step, arising first in Cnidaria that allowed for the development of the mucus-lined digestive cavity seen in higher metazoans. Mucus secretion by cnidarians has been moderately investigated in both corals and jellyfish, which among cnidarians are the ones that have shown the highest secretion rates to date. However, although in corals the production of mucus has received more attention, especially in view of the important ecological role played in coral reefs, in medusozoans the topic is little considered. Although the mucus secreted by corals has innumerable and important immunological, nutritional, and protective responsibilities, it should be remembered that jellyfish too represent a fundamental component of marine trophic web, playing numerous and important roles that are still unclear today. What is certain is that jellyfish are characterized (especially in the era of climate change) by large fluctuations in population density, the ecological implications of which are poorly understood. However, in both cases (Medusozoans and Anthozoans) to date some aspects relating to mucous secretions seem completely obscure, such as the microbiome and its variations as a function of environmental conditions or ontogenetic development, its implications in the field of immunological ecology, the consequent energy costs and finally the role played by the mucus in evolutionary terms. This review summarizes the properties, functions, ecological implications and evolutionary importance of mucus, in cnidarians, mainly focusing its roles in corals and jellyfish. Understanding these aspects relating to the ecological and evolutionary importance played by mucus is of fundamental importance for the ecosystems functioning.

The harmful jellyfish Cyanea nozakii Kishinouye has frequently occurred on Korean coasts, and its blooms have caused serious ecological and economic damages. DNA sequences of the C. nozakii for molecular detection and discrimination are relatively scarce. In this study, we determined the complete sequence of a single unit of tandemly repeated ribosomal DNA (rDNA) of the Korean C. nozakii and characterized the molecular features of the rDNA. The complete rDNA contained 8,003 bp (48.4% GC) with the same gene arrangement (18S, ITS1, 5.8S, ITS2, 28S, and IGS) to the typical eukaryotes. Dot plot analysis showed that the coding regions (18S, 5.8S, and 28S) were highly conserved, while the non-coding regions (ITS1, ITS2, and IGS) were more variable and parsimony-informative. The IGS contained a putative transcription termination signal (poly(T) tract) and four repeats of block minisatellites. Phylogenetic analyses using 18S and 28S rDNA revealed well-resolved relationships of C. nozakii within the order Semaeostomeae, separating it from other Cyanea species. The complete rDNA sequence provides various options for the selection of jellyfish taxonomic markers and may be useful for discriminating between species of C. nozakii and phylogeny reconstruction with close relatives.

Abstract Background Jellyfish stings are known to induce allergic skin reactions; however, case reports of anaphylaxis after jellyfish ingestion have been increasing, especially in Asian countries. Some cases of anaphylaxis after jellyfish ingestion have been reported in patients with a previous history of frequent jellyfish stings. Herein, we report a pediatric patient with anaphylaxis after jellyfish ingestion with no history of jellyfish stings. Case presentation A 14-year-old girl developed two episodes of anaphylaxis, and her diet diaries revealed that edible jellyfish was common to the meals in both the anaphylaxis events. A skin prick test using five types of edible jellyfish products revealed a positive reaction to some jellyfish, and anaphylaxis was observed after the ingestion of jellyfish in an oral food challenge test. She had no history of jellyfish stings or frequent swimming in the ocean. The basophil activation test showed positive results on stimulation with extracts from various types of edible jellyfish. We observed serum immunoglobulin E (IgE) reactivity to purified jellyfish collagen and jellyfish acid-soluble extracts. Moreover, immunoblotting analysis showed IgE reactivity to two bands at approximately 40 and 70 kDa using purified jellyfish collagen, which may be a causative antigen. Conclusions Edible salted jellyfish can be one of the causative foods of anaphylaxis. Clinicians should be aware of the possibility of anaphylactic reactions due to jellyfish ingestion even without a history of jellyfish stings.

High throughput low-density SNP arrays provide a cost-effective solution for population genetic studies and monitoring of genetic diversity as well as population structure commonly implemented in real time stock assessment of commercially important fish species. However, the application of high throughput SNP arrays for monitoring of invasive species has so far not been implemented. We developed a species-specific SNP array for the invasive comb jelly Mnemiopsis leidyi based on whole genome re-sequencing data. Initially, a total of 1,395 high quality SNPs were identified using stringent filtering criteria. From those, 192 assays were designed and validated, resulting in the final panel of 116 SNPs. Markers were diagnostic between the northern and southern M. leidyi lineages and highly polymorphic to distinguish populations. Despite using a reduced representation of the genome, our SNP panel yielded comparable results to using a whole genome re-sequencing approach (832,323 SNPs), recovering similar values of genetic differentiation between samples and detecting the same clustering groups when performing Structure analyses. The resource presented here provides a cost-effective, high throughput solution for population genetic studies, allowing to routinely genotype large number of individuals. Monitoring of genetic diversity and effective population size estimations in this highly invasive species will allow for the early detection of new introductions from distant source regions or hybridization events. Thereby, this SNP chip represents an important management tool in order to understand invasion dynamics and opens the door for implementing such methods for a wider range of non-indigenous invasive species.

This data article includes a qualitative and quantitative description of the gelatinous macrozooplankton community of the North Sea during January-February 2021. Sampling was conducted during the 1st quarter International Bottom Trawl Survey (IBTS) on board the Danish R/V DANA (DTU Aqua Denmark) and the Swedish R/V Svea (SLU Sweden), as part of the ichthyoplankton investigation during night-time. A total of 147 stations were investigated in the western, central and eastern North Sea as well as the Skagerrak and Kattegat. Sampling was conducted with a 13 m long Midwater Ring Net (MIK net, Ø 2 m, mesh size 1.6 mm, cod end with smaller mesh size of 500 µm), equipped with a flow meter. The MIK net was deployed in double oblique hauls from the surface to c. 5 m above the sea floor [1,2]. Samples were visually analysed unpreserved on a light table and/or with a stereomicroscope or magnifying lamp within 2 hours after catch. A total of 13,510 individuals were counted/sized. Twelve gelatinous macrozooplankton species or genera were encountered, namely the hydrozoan Aequorea vitrina, Aglantha digitale, Clytia spp., Leuckartiara octona, Tima bairdii, Muggiaea atlantica; the scyphozoans Cyanea capillata and Cyanea lamarckii and the ctenophores Beroe spp., Bolinopsis infundibulum, Mnemiopsis leidyi, Pleurobrachia pileus. Abundance data are presented on a volume specific (m−3) and area specific (m−2) basis. Size data have been used to estimate wet weights based on published length-weight regressions (see Table 1). For the groups i) hydrozoan jellyfish, ii) scyphozoan jellyfish, iii) ctenophores, as well as iv) grouped gelatinous macrozooplankton, spatial weight specific distribution patterns are presented. This unpublished dataset contributes baseline information about the gelatinous macrozooplankton diversity and its specific distribution patterns in the extended North Sea area during winter (January-February) 2021. These data can be an important contribution to address global change impacts on marine systems, especially considering gelatinous macrozooplankton abundance changes in relation to anthropogenic stressors.

The phylum Cnidaria is composed of corals, jellyfish, hydras, and sea anemones. Cnidarians are well-known for their regenerative capability, with many species maintaining the ability to regenerate complete structures. This regenerative capacity has been used casually for propagation purposes (via dissection) for some cnidarians used in laboratory research but has yet been documented in a manner meant to be reproducible. One such cnidarian model system is the scyphozoan jellyfish Cassiopea xamachana. C. xamachana has become an emerging model system for studying the cnidarian-algal symbiotic relationship, so determining a reliable and fast method for expansion of laboratory animals is crucial. Here we outline a reproducible propagation method for continued generation and growth of C. xamachana polyps. This article has an associated First Person interview with the first author of the paper.

Citizen science projects are designed to encourage involvement of the public with science. Understanding demographics of participants and factors that motivate or create barriers to participation are central in ensuring citizen science is effective. Citizen science is not new to Asia, but its implementation is underrepresented in the published literature of that geographic area, with the current focus largely on Western countries. Here, we consider the experience of citizen scientists participating in the Hong Kong Jellyfish Project. Survey responses (N = 87) indicate demographics similar to other citizen science programs, with participant gender reflective of the general population, and participants typically in full-time employment and highly educated. The main motivating factors for participation were: the project had meaningful goals, and participants wanted to contribute to science and to learn more about jellyfish. The main barriers to participation were: not being aware that absence of jellyfish was a valid observation, lack of knowledge, and lack of time. Notably, survey responses indicate inclusive bilingual communication made the project more appealing to respondents, improved participation, and increased motivation. Interestingly, these results indicate demographic traits, motivating factors, and barriers to participation of citizen scientists in Hong Kong are similar to elsewhere, and further research should be conducted to see if the same patterns persist across other cultural contexts. Where recognized, these motivational factors and barriers can inform the design of citizen science projects to more effectively attract and engage participants.

Abstract Jellyfish are useful genetic indicators for aquatic ecosystems as they have limited mobility and are highly exposed to the water column. By using comparative genomics and the molecular clock (timetree) of Rhizostoma pulmo, we revealed a divergence point between the East and West Mediterranean Sea (MS) populations that occurred 4.59 million years ago (mya). It is suggested that the two distinct ecological environments we know today were formed at this time. We propose that before this divergence, the highly mixed Atlantic and Mediterranean waters led to the wide dispersal of different species including R. pulmo. At 4.59 mya, the Western and Eastern MS were formed, indicating the possibility of a dramatic environmental event. For the first time, we find that for the jellyfish we examined, the division of the MS in east and west is not at the Straits of Sicily as generally thought, but significantly to the east. Using genomics of the Aurelia species, we examined contemporary anthropogenic impacts with a focus on migration of scyphozoa across the Suez Canal (Lessepsian migration). Aurelia sp. is among the few scyphozoa we find in both the MS and the Red Sea, but our DNA analysis revealed that the Red Sea Aurelia sp. did not migrate or mix with MS species. Phyllorhiza punctata results showed that this species was only recently introduced to the MS as a result of anthropogenic transportation activity, such as ballast water discharge, and revealed a migration vector from Australia to the MS. Our findings demonstrate that jellyfish genomes can be used as a phylogeographic molecular tool to trace past events across large temporal scales and reveal invasive species introduction due to human activity.