Marine Envenomation in Okinawa: Overview and Treatment Concept.

Okinawa prefecture is a popular tourist destination due to its beaches and reefs. The reefs host a large variety of animals, including a number of venomous species. Because of the popularity of the reefs and marine activities, people are frequently in close contact with dangerous venomous species and, thus, are exposed to potential envenomation. Commonly encountered venomous animals throughout Okinawa include the invertebrate cone snail, sea urchin, crown-of-thorns starfish, blue-ringed octopus, box jellyfish, and fire coral. The vertebrates include the stonefish, lionfish, sea snake, and moray eel. Treatment for marine envenomation can involve first aid, hot water immersion, antivenom, supportive care, regional anesthesia, and pharmaceutical administration. Information on venomous animals, their toxins, and treatment should be well understood by prehospital care providers and physicians practicing in the prefecture.

First record of association of copepods with highly venomous box jellyfish Chironex, with description of new species of Paramacrochiron (Cyclopoida: Macrochironidae).

Paramacrochiron chironecicola n. sp. (Copepoda: Cyclopoida: Macrochironidae) is described from the highly venomous box jellyfish Chironex sp. collected from Malampaya Sound, Palawan Island, The Philippines. This is the first record of copepods associated with cubozoan medusae, although other cnidarian groups such scyphozoans, hydrozoans, and anthozoans are common hosts for symbiotic copepods. The infection sites were on the subumbrella, pedalium, and rhopalium, but also rarely on the adradial furrow. The new species is distinguished from other congeners by a combination of the following features: (1) the fifth pedigerous somite dorsally covering the anterior part of the female genital double-somite; (2) the fine structures of the antenna (relative lengths of segments) and maxilliped (positions of terminal elements) of the female; (3) the relatively long outer spines on the exopodal segments of legs 1-4; (4) the relatively long and thick female leg 5 bearing a long protopodal seta which reaches to the distal margin of the exopod; (5) the relatively short caudal ramus in the female; and (6) the plump prosome and short urosome in the male. Since members of the genus typically parasitize scyphozoans, especially rhizostomes, the association of this parasitic copepod on cubozoans may reflect the relatively close phylogenetic relationship between cubozoans and scyphozoans.

Nematocyst Types and Characteristics in the Tentacles of Gershwinia thailandensis and Morbakka sp. (Cubozoa: Carybdeida) from the Gulf of Thailand.

Nematocysts, specialized stinging cells in cnidarians, play a crucial role in both defense and prey capture, containing venomous, coiled tubes within a capsule. While box jellyfish are recognized as a medical threat, information on the nematocysts of species like Gershwinia thailandensis and Morbakka sp. from Thai waters remains sparse. This study explores the types and morphology of nematocysts found in the tentacles of these species using light and scanning electron microscopy. We identified three nematocyst types: club-shaped microbasic p-mastigophores, oval isorhizas, and oval microbasic p-rhopaloids. Notably, significant differences in capsule sizes were observed, especially in the microbasic p-mastigophores and isorhizas. The discharge tubules tapered from the proximal to the distal ends, featuring arrow-shaped spines in a helical pattern. A distinct lancet structure was present in both microbasic p-mastigophores and p-rhopaloids. These findings suggest that variations in nematocyst size and morphology may be linked to evolutionary adaptations, functional roles, and venom toxicity. Further research into venom discharge mechanisms could offer valuable insights into the ecological and medical importance of these cnidarians.

Elucidation of Medusozoan (Jellyfish) Venom Constituent Activities Using Constellation Pharmacology.

Within the phylum Cnidaria, sea anemones (class Anthozoa) express a rich diversity of ion-channel peptide modulators with biomedical applications, but corollary discoveries from jellyfish (subphylum Medusozoa) are lacking. To bridge this gap, bioactivities of previously unexplored proteinaceous and small molecular weight (~15 kDa to 5 kDa) venom components were assessed in a mouse dorsal root ganglia (DRG) high-content calcium-imaging assay, known as constellation pharmacology. While the addition of crude venom led to nonspecific cell death and Fura-2 signal leakage due to pore-forming activity, purified small molecular weight fractions of venom demonstrated three main, concentration-dependent and reversible effects on defined heterogeneous cell types found in the primary cultures of mouse DRG. These three phenotypic responses are herein referred to as phenotype A, B and C: excitatory amplification (A) or inhibition (B) of KCl-induced calcium signals, and test compound-induced disturbances to baseline calcium levels (C). Most notably, certain Alatina alata venom fractions showed phenotype A effects in all DRG neurons; Physalia physalis and Chironex fleckeri fractions predominantly showed phenotype B effects in small- and medium-diameter neurons. Finally, specific Physalia physalis and Alatina alata venom components induced direct excitatory responses (phenotype C) in glial cells. These findings demonstrate a diversity of neuroactive compounds in jellyfish venom potentially targeting a constellation of ion channels and ligand-gated receptors with broad physiological implications.

Species-specific eDNA assay development for enhanced box jellyfish risk management in coastal environments.

Human interaction with marine creatures holds both positive and negative dimensions. Coastal communities benefit from marine environments, relying on them for sustenance and livelihoods. Fishing activities support economies, and marine biodiversity contributes to overall ecosystem health. However, challenges like overfishing, habitat destruction, and pollution pose threats to both marine life and human communities. Recently, there has been widespread concern regarding the potential increase in jellyfish populations across global marine ecosystems, attributed mainly to environmental factors such as climate drivers and anthropogenic forces, or their complex interactions. Encounters with hazardous marine species, such as box jellyfish, exemplify the dangers associated with coastal activities. Unintended interactions may lead to stings, injuries, and even fatalities, necessitating proactive measures and advanced technologies. This study addresses the inadequacies of existing measures in preventing box jellyfish incidents by introducing environmental DNA (eDNA) assays for detecting the deadly Chiropsoides buitendijki and focuses on developing qPCR and dPCR-based eDNA assays. Emphasising prevention over treatment, the study establishes a proactive system to assess C. buitendijki distribution across 63 tourist beaches in the Gulf of Thailand. Comparative analysis highlights the superior performance of dPCR over qPCR and traditional surveys. The dPCR experiment yielded positive results for all eDNA samples collected at sites where C. buitendijki had previously been identified. Remarkably, the eDNA testing also detected positive results in 16 additional sample locations where no physical specimens were collected, despite reported jellyfish stings at some of these sites. These findings underscore the precision and efficacy of the proposed eDNA detection technology in the early detection and assessment of box jellyfish distribution. This advancement therefore not only aids ecological research but also serves as a valuable tool for safeguarding public health, providing an early warning system for potential jellyfish encounters. Balancing positive human-marine interactions with effective risk mitigation strategies is crucial for sustainable coexistence, the preservation of marine ecosystems, and human well-being.

Differences in clinical manifestations between cases stung by single-tentacle and multiple-tentacle box jellyfish over two decades.

There are no routine laboratory investigations to identify jellyfish species and toxins in Thailand. Distinguishing clinical manifestation is important for medical care and also recommendations for the population. This study aimed to describe the clinical manifestations of box jellyfish stinging cases and determine differences between cases stung by single- (SBJ) and multiple-tentacle box jellyfish (MBJ). This retrospective study was conducted in Thailand. Data regarding injuries and deaths eligible for inclusion were those pertinent to stinging by box jellyfish under the National Surveillance System of Injuries and Deaths Caused by Toxic Jellyfish. All cases detected by the Toxic Jellyfish Networks were investigated. There were 29 SBJ, 92 MBJ, and 3 SBJ/or MBJ cases in the period 1999 to 2021. In about half of the cases in each group had abnormal heart rates and about one-third had respiratory distress. The SBJ group had a high proportion of pain in the other parts of the body (38.2%), abdominal cramps (13.8%), fatigue (24.1%), anxiety/agitation (24.1%), and there was no death. The MBJ group had a high proportion of severe pain and severe burning pain at the site of the wounds (44.3%), swelling/edema at the affected organs/areas (46.8%), collapse/near-collapse (30.4%), worse outcomes (9.8%), and 9.8% deaths. In comparison to the MBJ group, the SBJ group were 13.4 times (95% Confidence Intervals of Relative Risk: 4.9, 36.6) and 6.1 times (1.2, 31.4) more likely to have pain in other parts of the body and abdominal cramps, subsequently. MBJ group was 1.8 times (1.4, 2.2) more likely to have pain at wounds than the SBJ group. Some initial symptoms might make health professionals misdiagnose SBJ as MBJ stinging. The Irukandji-like syndrome that appeared later among SBJ cases is the clue for correct diagnosis. These results are useful for the improvement of diagnosis, medical care, and surveillance.

A New Species of Box Jellyfish (Cnidaria: Tripedaliidae: Tripedalia) from Hong Kong, China.

We describe a box jellyfish, Tripedalia maipoensis sp. nov., based on samples collected from a shrimp pond in Hong Kong. This new species is morphologically distinct from other species of the family Tripedaliidae by the following combination of characters: (1) three pedalia at each bell corner; (2) each pedalium with one tentacle; and (3) velarium with forked canals. Phylogenetic analyses based on a concatenated dataset of the 16S, 18S and 28S rRNA genes show that T. maipoensis sp. nov. is sister to the morphologically similar species T. cystophora, but the two species exhibit 17.4% divergence in the 16S rRNA gene, supporting T. maipoensis sp. nov. as a distinct species. This new species represents the fourth described species of Tripedaliidae, and the first record of the family in Chinese coastal waters.

Learning in Cnidaria: a summary.

Based 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.

Expression of Opsins of the Box Jellyfish Tripedalia cystophora Reveals the First Photopigment in Cnidarian Ocelli and Supports the Presence of Photoisomerases.

Cubomedusae, or box jellyfish, have a complex visual system comprising 24 eyes of four types. Like other cnidarians, their photoreceptor cells are ciliary in morphology, and a range of different techniques together show that at least two of the eye types-the image-forming upper and lower lens eyes-express opsin as the photopigment. The photoreceptors of these two eye types express the same opsin (Tc LEO), which belongs to the cnidarian-specific clade cnidops. Interestingly, molecular work has found a high number of opsin genes in box jellyfish, especially in the Caribbean species Tripedalia cystophora, most of which are of unknown function. In the current study, we raised antibodies against three out of five opsins identified from transcriptomic data from T. cystophora and used them to map the expression patterns. These expression patterns suggest one opsin as the photopigment in the slit eyes and another as a putative photoisomerase found in photoreceptors of all four eyes types. The last antibody stained nerve-like cells in the tentacles, in connection with nematocytes, and the radial nerve, in connection with the gonads. This is the first time photopigment expression has been localized to the outer segments of the photoreceptors in a cnidarian ocellus (simple eye). The potential presence of a photoisomerase could be another interesting convergence between box jellyfish and vertebrate photoreceptors, but it awaits final experimental proof.

Corrigendum: Expression of opsins of the box jellyfish Tripedalia cystophora reveals the first photopigment in cnidarian ocelli and supports the presence of photoisomerases.

[This corrects the article DOI: 10.3389/fnana.2022.916510.].

Fatal jellyfish envenoming-Pediatric and geographic vulnerabilities.

Lethal jellyfish envenoming is a very rare event. Two illustrative cases of fatalities following envenomation from the multi-tentacled box jellyfish, Chironex fleckeri, are reported that involved a six-year-old boy and a three-year-old girl, both of whom had been playing in shallow beach waters in remote Northern Territory communities (Australia). A recommended approach to autopsy in suspected cases is described, which should include examination of the clothing and skin surfaces for the fine tentacles of Chironex fleckeri. In addition, the combined length and maximum width of tentacle marks should be measured/calculated and collection of unfixed tentacles with adhesive tape onto a glass slide should be undertaken to check for nematocysts. Such rare cases show that children are at higher risk of a lethal outcome, particularly if they are resident in remote coastal tropical communities.

Rapid and Accurate Species-Specific PCR for the Identification of Lethal Chironex Box Jellyfish in Thailand.

Box jellyfish are extremely potent venom-producing marine organisms. While they have been found worldwide, the highest health burden has been anticipated to be the tropical Indo-Pacific of Southeast Asia (SEA). At least 12 Cubozoan species have now been documented in Thai waters, and many of them inflict acutely lethal strings, especially those under the order Chirodropida. Our previous study has successfully differentiated species of box jellyfish using DNA sequencing to support the morphological study. In this study, we specifically designed polymerase chain reaction (PCR) primers for the 16S ribosomal RNA (rRNA) gene and the mitochondrial DNA cytochrome oxidase subunit I (COI) gene of lethal Thai Chironex species. The SYBR green-based real-time PCR panel was performed for rapid species identification. The sensitivity and specificity of the panel were determined by testing samples of different species. Moreover, we applied the panel to the tentacle sample from a real patient, which helped confirm the animal-of-cause of envenomation. Our results show a success for species identification of box jellyfish using 16S rRNA and COI PCR panel, which revealed congruence between molecular and morphological identification. Furthermore, the panel worked very well with the unknown samples and jellyfish tissue from the real envenomation case. The results demonstrated that molecular panels were able to identify three species of Chironex box jellyfish both rapidly and accurately, and can be performed without having a complete specimen or morphological study.

Irukandji-like syndrome caused by single-tentacle box jellyfish found in Thailand, 2007-2019.

BACKGROUND: Irukandji syndrome definition is still widely misunderstood. Irukandji-like syndrome is more unclear than Irukandji syndrome. This study aimed to describe Irukandji-like syndrome in cases involving stinging by single-tentacle box jellyfish species in Thailand. MATERIALS AND METHODS: Surveillance system and networks of toxic jellyfish incidents were established to enable case detection. In the period 2007 to 2019, all cases of stinging by single-tentacle box jellyfish resulting in collapse, hospital attendance or death were investigated. RESULTS: The majority of the 19 Irukandji-like syndrome cases were male (68.2%), median age 35.0 years (range 6.0-60.0), and Thai nationality (52.3%). Clinical manifestations of Irukandji-like syndrome were categorised as severe wound pain with immediate systemic reaction (66.7%), moderate wound pain with gradual systemic reaction (16.7%), and moderate wound pain with the immediate systemic reaction after a physical/chemical trigger (16.7%). The pain occurring when being stung differed from the pain occurring during the systemic reaction. The five most common symptoms were pain (100.0%), high blood pressure (100.0%), palpitations (86.7%), respiratory distress (52.6%), and near collapse/collapse (31.6%). The pain occurs when being stung was excruciating or burning pain at the wounds, felt like an electric shock, and rapidly expanded to heart pain. While the pain occurring during the systemic reaction was back pain, muscle pain, joint pain, abdominal pain, and body aches. The marks from the tentacles appeared similar in appearance to the caterpillar tracks of tanks. In 6 cases the species could be identified and all of them involving the Morbakka spp. CONCLUSIONS: This was the largest study of Irukandji-like syndrome cases involving stings by single-tentacle box jellyfish in Thailand and the different clinical manifestations might be caused by different species of single-tentacle box jellyfish.

Gonadal cnidocytes in the cubozoan Tripedalia cystophora Conant, 1897 (Cnidaria: Cubozoa).

Cubozoans have a complex lifecycle in many ways similar to the scyphozoan lifecycle. The sexual reproduction within cubozoans varies between species with one clade having copulation and internal fertilization and the release of planula larvae. This cubozoan clade, the family Tripedaliidae, includes three species, Copula sivickisi, Tripedalia cystophora, and Tripedalia binata. In a recent study, it was suggested that in C. sivickisi cnidocytes play a new and important role during the sexual reproduction. Male derived cnidocytes anchor sperm packages to the female gonads and female derived cnidocytes protect the externalized embryo strand. Here, we have examined the gonads and gametes of T. cystophora and our results reveal that the male produced spermatozeugmata have a high number of isorhiza type cnidocytes, which are transferred along with the sperm during copulation. This adds further support to our hypothesis that they are important for sperm anchorage. The female gonads are lacking cnidocytes all together showing that cnidocyte production is not just a default state of the epithelium in these animals.

Revision of the genus Carybdea (Cnidaria: Cubozoa: Carybdeidae): clarifying the identity of its type species Carybdea marsupialis.

While records of Carybdea marsupialis in the literature suggest a worldwide distribution of this species, the validity of some of these records has been questioned recently, as has the validity of some nominal Carybdea species. We inspected material of all known species of Carybdea from multiple locations (i.e. Spain, Algeria, Tunisia, Puerto Rico, California, Hawaii, Australia, South Africa, and Japan) using morphological and genetic tools to differentiate Carybdea species as well as understand their evolutionary relationships. We observed morphological differences between adult medusae of Mediterranean and Caribbean C. marsupialis; the most obvious differences were the structure of the phacellae, the structure of the pedalial canal knee bend, and the number and structure of the velarial canals. The characters of the adult Mediterranean specimens agree with the description provided by Claus (1878) for individuals of C. marsupialis from the Adriatic Sea (Italy); specimens from the Caribbean (Puerto Rico) agreed with the description of C. xaymacana by Conant (1897). Significant differences between both species were also observed in the newly released medusa stage. Further, we resolved a discord about the undefined polyp culture originating from Puerto Rico that was long considered Carybdea marsupialis but should be referred to as C. xaymacana. Although C. marsupialis is currently considered the only species of Cubozoa to occur in the Mediterranean, specimens collected in Algeria and Tunisia suggest that species of Alatinidae may also be present in the Mediterranean. Our investigations indicate that Carybdea spp. are more restricted in their geographical distribution than has been recognized historically. These findings confirm that Carybdea arborifera Maas, 1897 from Hawaii, Carybdea branchi, Gershwin Gibbons, 2009 from South Africa, Carybdea brevipedalia Kishinouye, 1891 from Japan, Carybdea confusa Straehler-Pohl, Matsumoto Acevedo, 2017 from California, Carybdea marsupialis Linnaeus, 1758 from the European Mediterranean Sea, Carybdea rastonii Haacke, 1886 from South Australia, and Carybdea xaymacana, Conant, 1897 from the Caribbean Sea are valid names representing distinct species, rather than synonyms. A taxonomic key for all valid species is provided, and a neotype for C. marsupialis is designated.

Electrophysiological activity of a neurotoxic fraction from the venom of box jellyfish Carybdea marsupialis.

Carybdea marsupialis is a widely distributed box jellyfish found in the Mediterranean and in the tropical waters of the Caribbean Sea. Its venom is a complex mixture of biologically active compounds that are used to catch prey. In order to evaluate the activity of the neurotoxins in the venom, bioassays were carried out using the marine crab Ocypode quadrata. The proteins with neurotoxic effect were partially purified using low-pressure liquid chromatography techniques. Gel filtration (Sephadex G-50M) was used as the first step and the active fraction in crabs was passed through a QAE Sephadex A-25 column. Finally, the active fraction was run onto a Fractogel EMD SO3- column. No further purification step could be carried out due to the loss of neurotoxic activity. The Fractogel EMD SO3- fraction was analyzed electrophysiologically using the voltage-clamp technique in Xenopus laevis oocytes expressing membrane proteins from rat brain through mRNA injection. The crude venom and a fraction were observed to affect crustaceans and showed at least two types of bioactivity in oocytes expressing brain proteins. The effects were dose-dependent and completely reversible. These results evidence the presence of neurotoxins in Carybdea marsupialis venom that act on membrane proteins of the vertebrate nervous system.

In vitro angiotensin I converting enzyme inhibition by a peptide isolated from Chiropsalmus quadrigatus Haeckel (box jellyfish) venom hydrolysate.

The anti-angiotensin I converting enzyme activity of box jellyfish, Chiropsalmus quadrigatus Haeckel venom hydrolysate was studied. The venom extract was obtained by centrifugation and ultrasonication. Protein concentration of 12.99 µg/mL was determined using Bradford assay. The pepsin and papain hydrolysate was tested for its toxicity by Limit test following the OECD Guideline 425 using 5 female Sprague-Dawley rats. Results showed that the hydrolysate is nontoxic with an LD50 above 2000 mg/kg. In vitro angiotensin I converting enzyme (ACE) inhibitory activity was determined using ACE kit-WST. Isolation of ACE inhibitory peptides using column chromatography with SP-Sephadex G-25 yielded 8 pooled fractions with fraction 3 (86.5%) exhibiting the highest activity. This was followed by reverse phase - high performance liquid chromatography (RP-HPLC) with an octadecyl silica column (Inertsil ODS-3) using methanol:water 15:85 at a flow rate of 1.0 mL/min. Among the 13 fractions separated with the RP-HPLC, fraction 3.5 exhibited the highest ACE inhibitory activity (84.1%). The peptide sequence ACPGPNPGRP (IC50 2.03 µM) from fraction 3.5 was identified using Matrix-assisted laser desorption/ionization with time-of-flight tandem mass spectroscopy analysis (MALDI-TOF/MS).

Marine envenomations in returning French travellers seen in a tropical diseases unit, 2008-13.

BACKGROUND: Travel and aquatic activities are increasing in tropical regions. The risk and the spectrum of marine envenomation are unknown in travellers. This work aims to evaluate the prevalence and the characteristics of marine envenomations in returning travellers. METHODS: We retrospectively studied the medical charts of all returning travellers presenting with a health problem in a French tropical disease unit between 2008 and 2013, with focus on travellers complaining of marine envenomation. Characteristics of each type of envenomation are described. RESULTS: Of the 3315 travellers seen during the study period, 43 consulted for a presumed marine envenomation. Six patients were excluded, leaving 37 cases of confirmed marine envenomation. It corresponds to a prevalence of 1.1%. Sex ratio was balanced with 18 men and 19 women. Median age was 42 years (range 25-68 years). Median travel duration was 14 days (range: 6-62 days). The main travel destination was Southeast Asia in 10 cases, followed by islands of East Africa in seven cases. Median elapsed time between envenomation and consultation was 14 days (range: 2-130 days). The purpose of travel was tourism in all cases. The main clinical aspects were oedema, sting marks, cellulitis and flagellations. Eleven cases were presumably caused by corals, 10 by stonefish, 8 by jellyfish, 2 by weever fish, 2 by starfish, 2 by stingray, 1 by lionfish and 1 by sea anemone. CONCLUSION: Prevalence of marine envenomation is low in returning travellers. They are mostly caused by corals, stonefish and jellyfish.

Meteoronakishinouyei, a new family, genus and species (Cnidaria, Cubozoa, Chirodropida) from Japanese Waters.

A new family, genus and species of cubozoan box jellyfish belonging to the order Chirodropida is reported from the eastern Japan. Meteoronakishinouyei gen. et sp. n. possesses the following unique morphological characters with respect to other known species in the Chirodropida: having one tentacle per scalpel-like unbranched pedalium and slightly raised unbranched gastric saccules. A comparative table of the primary diagnostic characters of genus and order in the Chirodropida is given. The order Chirodropida is redefined. The family Chiropsellidae is established. Discussion is provided on the implications for these findings on our current understanding of Cubozoan systematics.