Box Jellyfish Research Articles

Updated Nematocyst Types in Tentacle of Venomous Box Jellyfish, Chironex indrasaksajiae (Sucharitakul, 2017) and Chiropsoides buitendijki (Horst, 1907) (Cnidaria, Cubozoa) in Thai Waters

The multiple-tentacle box jellyfish, Chironex indrasaksajiae (Sucharitakul, 2017) and Chiropsoides buitendijki (Horst, 1907), are venomous species found in Thai waters. They are responsible for numerous envenomations through their stinging organelles, nematocysts. These specialized microscopic structures discharge venom, yet detailed knowledge of their types and morphology in these species remains limited. This study updates the characterization of nematocyst types and features in C. indrasaksajiae and C. buitendijki using light and scanning electron microscopy for detailed examination. Four distinct nematocyst types were identified: banana-shaped microbasic p-mastigophores, oval-shaped microbasic p-rhopaloids, sub-spherical microbasic p-rhopaloids, and rod-shaped isorhizas. In C. indrasaksajiae, banana-shaped microbasic p-mastigophores exhibited significant intraspecific variability, ranging from 30.26 µm to 102.56 µm in length and 6.42 µm to 17.01 µm in width. Conversely, C. buitendijki showed a narrower size range, 72.17 µm to 98.37 µm in length and 10.73 µm to 16.48 µm in width, based on multiple individuals. The size ranges for the other nematocyst types were consistent across both species. This study enhances the understanding of nematocyst morphology in these box jellyfish, providing a foundation for further research on venom delivery mechanisms and improved management of jellyfish envenomations in Thai waters.

Molecular signatures reveal intra-species divergence, undetectable by traditional morphology, in the deadly box jellyfish, Chironex yamaguchii (Cubozoa; Chirodropidae) of Western Pacific

Molecular signatures reveal intra-species divergence, undetectable by traditional morphology, in the deadly box jellyfish, Chironex yamaguchii (Cubozoa; Chirodropidae) of Western Pacific

Integrating complexity in population modelling: From matrix to dynamic models

Matrix models are widely used in population ecology studies and are valuable for analysing population dynamics, although they are limited in the use of time-varying parameters. This limitation can be overcome by dynamic models. In this study, we revisit a previously published study on a matrix model of a population of the box jellyfish Carybdea marsupialis (L. 1758) in the Western Mediterranean. A dynamic model integrating the transition matrix of the original model is developed in STELLA Architect with the following improvements: (1) Sensitivity study of the reliability of the methodology for calculating the transition matrix and estimation of the errors of the fitting parameters; (2) Closure of the jellyfish life cycle by adding the polyp stage. This will make it possible to simulate scenarios of ecological interest over several years such as a decline in food supply, jellyfish removal strategies, changes in drift currents and changes in substrate availability for planulae to settle. (3) The inclusion of more biological reality. In particular, a temporal pattern of strobilation is added, which improves the fit of the model to the field data.

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.

Environmental and ecological factors associated with stinging jellyfish at a tourism hotspot in the Gulf of Thailand

The waters of Thailand are associated with some of the most severe cases of envenomation from jellyfish in Asia, often attributed to the extensive marine recreational tourism industry it supports. The western Gulf of Thailand in particular has been shown to host among the highest abundances of box jellyfish, while also being home to some of the highest marine recreational tourism, such as along the Koh Samui archipelago. Here we utilise aspects of the same tourism industry to develop a deeper understanding of stinging jellyfish population dynamics, by combining citizen science at the island of Koh Tao, with dedicated in-situ surveys and remote sensing data. Our analyses of 170 box jellyfish sightings and 81 blooms of Pelagia sp. across a six-year period revealed a strong seasonal trend, with both groups being most abundant between July and December. Decision tree analysis of the complete observation dataset and multiple environmental variables revealed a combination of precipitation and lunar cycle to be the strongest predictors of the assessed stinging jellyfish at Koh Tao. Furthermore, blooms of Pelagia sp. were associated with extensive medusivory by a large diversity of predators, including reef building corals. These observations add to the growing literature showing that scleractinian corals are readily able to ingest larger prey items, either by solitary or protocooperative feeding strategies. Meanwhile, no consumption of box jellyfish medusae was recorded during the study. These findings may allow for improved tourism management practices while also supporting a wider biogeographic assessment of stinging jellyfish in south-east Asia.

Biomimetic Soft Robotic Jellyfish for Lentic Ecosystem Monitoring

Environmental monitoring of lentic ecosystems is well suited for swarm robotics applications since they can operate autonomously and cover large regions. For such a task, a locomotion mechanism is necessary for traversal. Due to the challenging nature of underwater environments, researchers often draw inspiration from nature to improve robot mechanical performance. A box jellyfish in a good inspiration due to their efficient jet propulsion. Soft and smart materials are helpful in mimicking their propulsion because they can perform flexible and complex movement. Shape memory alloy (SMA) springs have been used for this purpose, but their slow actuation rate is a well-known disadvantage. This project aims to improve cycle rate and thus swim speed by implementing a bistable spring configuration into a soft robotic jellyfish. The bistable mechanism stores energy slowly in the expansion of the elastic silicone bell, then releases it suddenly in a contraction which propels the robot forwards with a higher force than would be possible with direct SMA actuation. Additionally, the antagonistic arrangement of SMA springs reset each other and produce the same outward expansion on both up and down stroke, improving cycles speeds by removing the need for a dedicated reset stroke which is typically required before using the springs again. Also, increasing the number of spring pairs does not interfere with the actuation, meaning cycle rates can be further improved by cycling which pair of springs is active. The proof-of-concept device operates at a frequency of 0.4 Hz, and produces enough thrust while tethered to swim through a tank. Future work involves performing fluid visualization tests to validate a simple mathematical model of flow through the bell, as well as optimize the design, integrate onboard environment sensors and implement autonomy to allow operation in a larger swarm.

Copula lucentia sp. nov., a new box jellyfish (Cnidaria: Cubozoa: Carybdeida) from Western Mediterranean Sea

A new species of box jellyfish, Copula lucentia sp. nov., is described from El Campello, Spain, and compared to the holotype of Copula sivickisi that was successfully recovered after being lost for almost 60 years. So far, the only cubozoan species recorded in the Western Mediterranean was Carybdea marsupialis. The genus Copula just included the type species (Copula sivickisi) reported from different localities in the Pacific, Atlantic, and Indian Oceans. Morphologically, this new species possesses the typical characteristics of the genus Copula (four adhesive pads on the apex and a vertical keyhole-shaped rhopalial niche ostium) but it can be differentiated from the C. sivickisi holotype by the velarial canal pattern. In C. lucentia sp. nov., the velarial canal roots taper towards the velarial rim and each root bears one to two narrow triangular canals with sharp tips, resembling a bird beak. In contrast, the velarial canal roots of C. sivickisi bear two short, broad canals that increase breadth towards the velarial rim and split up into three- to six-lobed, finger-like canals with rounded tips, giving the canal pattern a paw-like appearance. Molecular analyses of mitochondrial cytochrome c oxidase subunit I (COI) and nuclear 16S ribosomal DNA genes confirm the distinction of the new species and show that there are even more Copula species than expected, but which will not be focused on here. This study highlights not only that there are species yet to be discovered in the Mediterranean Sea but that a revision of the genus Copula is necessary.

First report of Carybdea xaymacana Conant, 1897 (Cnidaria, Cubozoa, Carybdeida) in Colombia

Carybdea xaymacana Conant, 1897 is a box jellyfish belonging to the family Carybdeidae and is currently recorded from the Mexican Caribbean (State of Quintana Roo), Puerto Rico, the Bahamas, Jamaica, Panama, and Venezuela. Here, we report for the first time the presence of this species in Colombia, based on collections made in three departments of the Colombian Caribbean. Documenting the extension in the distribution range of this species is of great importance due to its ecological role in regional ecosys-tems.

Swimming ability of the Carybdea marsupialis (Cnidaria: Cubozoa: Carybdeidae): implications for its spatial distribution

AbstractAlthough usually considered part of the plankton, cubozoans are strong swimmers. The aim of this study was to determine the influence of the active swimming ability of the box jellyfish Carybdea marsupialis on the spatial distribution of a well‐studied population in the NW Mediterranean where adults and juveniles do not overlap geographically. To accomplish this, we analyzed the swimming speed, effective velocity, effective displacement index (EDI), and proficiency of 27 individuals with diagonal bell widths (DBWs) ranging from 1.1 to 36 mm. The laboratory analysis utilized conventional video recordings and the video analysis tool Tracker. Mean swimming speed for small juveniles, medium juveniles and adults was 9.7 ± 0.8, 21.9 ± 2.3 and 43.1 ± 1.8 mm s−1 (mean ± se), respectively. Effective velocity was also proportional to size, ranging from 5.0 ± 0.7 to 38.8 ± 3.1 mm s−1 (mean ± se). The calculated EDI for each group was 0.51 ± 0.05, 0.84 ± 0.06 and 0.90 ± 0.05 (mean ± se), respectively. Proficiency showed an inverse trend, from 6.4 ± 0.6 s−1 for the small juveniles to 1.36 ± 0.05 for adults (mean ± se). Comparing the swimming speed results with the local currents obtained from drifting buoys analyzed in the area, adults would be able to swim strongly enough to overcome almost 70% of the currents, whereas the small juveniles would not reach 17%. This would allow larger individuals to select their habitat, while smaller individuals are left dependent on advection. Although experiments adding currents in aquaria would be necessary to confirm these theoretical results, the data obtained would be useful in improving the performance of bio‐mathematical models used to predict jellyfish blooms since, even though the sting of C. marsupialis is non‐fatal, it may produce systemic effects in sensitive swimmers.

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.

Use of eDNA to Determine Source Locations of Deadly Jellyfish (Cubozoa) in an Open Coastal System

Challenges associated with cubozoan jellyfish detection and the limitations of current detection techniques limit the ability of scientists to fill critical knowledge gaps surrounding their ecology. Environmental DNA (eDNA), however, has proven useful as an ecological survey tool to detect and study these deadly jellyfish. This study aimed to leverage the power of eDNA to detect and explore the distribution of the Australian box jellyfish (Chironex fleckeri), encompassing both its medusae and polyp life history stages, within an open coastal bay (Horseshoe Bay) of Magnetic Island, Queensland, Australia. Our investigation focused on a hypothesis concerning the source locations of the jellyfish within Horseshoe Bay and, through a comparison of both life history stage distributions, aimed to determine potential population stock boundaries. eDNA results aligned with the predicted nearshore distribution of medusae. Further, the elusive benthic polyp stage was also detected. These findings confirmed Horseshoe Bay as a source location of the jellyfish. Moreover, our evidence supported a model that the area likely represents a population stock of the species. This adds to growing evidence suggesting some cubozoan jellyfish have population stocks of small spatial scales in both open and relatively closed ecosystems such as estuaries. In conclusion, this study serves as a notable example of eDNA’s ability to resolve critical knowledge gaps surrounding cubozoan ecology and to enhance the management ability of these deadly jellyfish to reduce envenomations.

Cubomedusae (Cubozoa, Carybdeida, Carukiidae) in Hong Kong, China: first records of cubozoans in Chinese waters confirmed using citizen science and digital authentication

The Hong Kong Jellyfish Project uses photographs and videos from citizen scientists to document the occurrence of jellyfish in this region. Based on these records, we describe sightings of two previously unrecorded species of box jellyfish, Malo filipina (Bentlage & Lewis, 2012) and an unidentified species of Morbakka sp. Gershwin, 2008, in Hong Kong Special Administrative Region, China. This understanding of where these species currently occur is important due to the potential impacts of box jellyfish on human activities and their role in local ecosystems.

Associative learning: Box jellyfish learns to avoid bumps

Operant conditioning- learning to do something for a desired outcome- has never been convincingly demonstrated in Cnidaria. A study now shows that box jellyfish, Tripedalia cystophora, can learn to avoid bumping into an obstacle based on visual cues.

Associative learning in the box jellyfish Tripedalia cystophora

Associative learning, such as classical or operant conditioning, has never been unequivocally associated with animals outside bilatarians, e.g., vertebrates, arthropods, or mollusks. Learning modulates behavior and is imperative for survival in the vast majority of animals. Obstacle avoidance is one of several visually guided behaviors in the box jellyfish, Tripedalia cystophora Conant, 1897 (Cnidaria: Cubozoa), and it is intimately associated with foraging between prop roots in their mangrove habitat. The obstacle avoidance behavior (OAB) is a species-specific defense reaction (SSDR) for T.cystophora, so identifying such SSDR is essential for testing the learning capacity of a given animal. Using the OAB, we show that box jellyfish performed associative learning (operant conditioning). We found that the rhopalial nervous system is the learning center and that T.cystophora combines visual and mechanical stimuli during operant conditioning. Since T.cystophora has a dispersed central nervous system lacking a conventional centralized brain, ourwork challenges the notion that associative learning requires complex neuronal circuitry. Moreover, since Cnidaria is the sister group to Bilateria, it suggests the intriguing possibility that advanced neuronal processes, like operant conditioning, are a fundamental property of all nervous systems.

Rapid and permanent cytotoxic effects of venom from Chiropsella bronzie and Malo maxima on human skeletal and cardiac muscle cells

Jellyfish envenomation is a global public health risk; Cubozoans (box jellyfish) are a prevalent jellyfish class with some species causing potent and potentially fatal envenomation in tropical Australian waters. Previous studies have explored the mechanism of action of venom from the lethal Cubozoan Chironex fleckeri and from Carukia barnesi (which causes “Irukandji syndrome”), but mechanistic knowledge to develop effective treatment is still limited. This study performed an in-vitro cytotoxic examination of the venoms of Chiropsella bronzie and Malo maxima, two understudied species that are closely related to Chironex fleckeri and Carukia barnesi respectively. Venom was applied to human skeletal muscle cells and human cardiomyocytes while monitoring with the xCELLigence system. Chiropsella bronzie caused rapid cytotoxicity at concentrations as low as 58.8 μg/mL. Malo maxima venom caused a notable increase in cell index, a measure of cell viability, followed by cytotoxicity after 24-h venom exposure at ≥11.2 μg/mL on skeletal muscle cells. In contrast, the cardiomyocytes mostly showed significant increased cell index at the higher M. maxima concentrations tested. These findings show that these venoms can exert cytotoxic effects and Malo maxima venom mainly caused a sustained increase in cell index across both human cell lines, suggesting a different mode of action to Chiropsella bronzie. As these venoms show different real-world envenomation symptoms, the different cellular toxicity profiles provide a first step towards developing improved understanding of mechanistic pathways and novel envenomation treatment.

The Dermatological Effects of Box Jellyfish Envenomation in Stinging Victims in Thailand: Underestimated Severity

The dermatological effects of box jellyfish envenomation among stinging victims in Thailand are not well reported, particularly concerning chronic effects. For first aid, different recommendations indicate the necessity for the removal of tentacles in life-threatening situations. This study aimed to describe the dermatological effects of box jellyfish envenomation and propose recommendations regarding first aid for victims in urgent care or life-threatening situations. Surveillance systems and Toxic Jellyfish Networks were established to improve detection and investigation. The networks investigated all severe victims of jellyfish envenomation. A retrospective study was conducted, and victims of stinging by box jellyfish investigated from 1999 to 2021 were included. One hundred and twenty-four victims were recorded. The majority of victims were males (55%), tourists (69%), and Thai nationals (49%). Direct contact had more severe consequences than indirect contact. Dermatological effects included edema, erythematous caterpillar track-like rash, blistering, bullae, papular eruption, necrosis, digital gangrene, recurrent dermatitis, dermal hypersensitivity, numbness, lichenification, hyperpigmentation, keloids, and scarring. Suffering and healing continued from several weeks to many years. Victims with multiple-tentacle box jellyfish stings had papular eruptions and greater severity of skin issues. All fatally envenomed victims collapsed within a few minutes and received incorrect/no first aid. The proposed first aid for life-threatening box jellyfish stings is continuous irrigation of the wound with vinegar for at least 30 s and initiation of cardiopulmonary resuscitation if there is no respiration or heartbeat. Tentacles often detach spontaneously, and removal is not always necessary, thus saving time. The findings provide input for improving diagnosis and treatment guidelines.

Evaluation of a Guest Lecture on Medical Emergency of Box Jellyfish Envenomation Pathophysiology and First Aid for Medical Students.

Lethal box jellyfish envenomation has been reported in Indonesia and other countries; therefore, medical students should be equipped with related knowledge. The aim of this study was to evaluate the results of summative exams by student cohort and gender and determine the factors that contribute to success in the summative exams after novel intensive instruction in box jellyfish envenomation pathophysiology and first aid in undergraduate medical students in Surabaya, Indonesia. This study used explanatory sequential mixed methods, consisting of a cross-sectional study and interviews. A total population sampling of 203 sixth-semester students was employed. Student cohort, gender, previous semester grade point average (GPA), and English proficiency test (EPT) were considered. All statistical tests were carried out using IBM® SPSS® Statistics version 24.0 for Macintosh. The study was complemented by interviews conducted with 20 students. The one-way ANOVA test showed that students from the 2016 cohort had significantly higher mean scores in the exam than the 2015 and 2014 cohorts (p=0.002). Independent samples t-test showed that such differences were not gender-specific (p=0.249). In the binary logistic regression, the GPA in the previous semester was the only factor that contributed to success in the summative exam (OR 3.031, 95% CI: 1.520-6.044). All students commented that the lecture and practicum were interesting and beneficial. However, some considered that the language barrier might have prevented them from understanding the topic well. Results of the summative exam differed by the student cohorts, and previous semester GPA was a predictor of success in the summative exam.

Histological Investigation of the Female Gonads of Chiropsalmus quadrumanus (Cubozoa: Cnidaria) Suggests Iteroparous Reproduction

The box jellyfish Chiropsalmus quadrumanus (Chirodropida: Cubozoa: Cnidaria) is common in warm waters. Although it is assumed that external fertilization is a characteristic of Chirodropida, the life history of C. quadrumanus is not yet known since its reproductive behavior has never been described, nor has the polyp has been found in nature. As a result, in the absence of documentation of reproductive behavior, we sought to test the hypothesis of external fertilization through a histological analysis of the female gonads. Herein, we analyze ten females collected in São Paulo and Rio de Janeiro (Brazil) and describe the gonadal organization and pattern of oocyte development. The discovery of four distinct stages of oocyte differentiation augments the scant existing reports of the structural and functional maturation of sex cells in Cubozoa species. Furthermore, the gonads of mature females comprise both mature (average diameter of 122 µm) and immature oocytes, suggesting that C. quadrumanus is iteroparous and exhibits multiple reproductive cycles during its life. Medusa bell size was not found to correlate with maturity state as even small females possessed a high percentage of oocytes in late vitellogenesis, suggesting that sexual maturation occurs rapidly in C. quadrumanus females.

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 visual opsin from jellyfish enables precise temporal control of G protein signalling

Phototransduction is mediated by distinct types of G protein cascades in different animal taxa: bilateral invertebrates typically utilise the Gαq pathway whereas vertebrates typically utilise the Gαt(i/o) pathway. By contrast, photoreceptors in jellyfish (Cnidaria) utilise the Gαs intracellular pathway, similar to olfactory transduction in mammals1. How this habitually slow pathway has adapted to support dynamic vision in jellyfish remains unknown. Here we study a light-sensing protein (rhodopsin) from the box jellyfish Carybdea rastonii and uncover a mechanism that dramatically speeds up phototransduction: an uninterrupted G protein-coupled receptor – G protein complex. Unlike known G protein-coupled receptors (GPCRs), this rhodopsin constitutively binds a single downstream Gαs partner to enable G-protein activation and inactivation within tens of milliseconds. We use this GPCR in a viral gene therapy to restore light responses in blind mice.