Sensory physiology: brainless eyes.
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Animals↗
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Results for “Cubozoa”
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Advanced optics in a jellyfish eye.
Cubozoans, or box jellyfish, differ from all other cnidarians by an active fish-like behaviour and an elaborate sensory apparatus. Each of the four sides of the animal carries a conspicuous sensory club (the rhopalium), which has evolved into a bizarre cluster of different eyes. Two of the eyes on each rhopalium have long been known to resemble eyes of higher animals, but the function and performance of these eyes have remained unknown. Here we show that box-jellyfish lenses contain a finely tuned refractive index gradient producing nearly aberration-free imaging. This demonstrates that even simple animals have been able to evolve the sophisticated visual optics previously known only from a few advanced bilaterian phyla. However, the position of the retina does not coincide with the sharp image, leading to very wide and complex receptive fields in individual photoreceptors. We argue that this may be useful in eyes serving a single visual task. The findings indicate that tailoring of complex receptive fields might have been one of the original driving forces in the evolution of animal lenses.
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A randomized paired comparison trial of cutaneous treatments for acute jellyfish (Carybdea alata) stings.
The objective of the study was to compare cutaneous treatments (heat, papain and vinegar) for acute jellyfish (Carybdea alata) stings. Healthy adult volunteer subjects received a single-tentacle jellyfish sting on each forearm. One forearm was treated with hot-water immersion (40-41 degrees C). This was compared with the other forearm, which was randomized to a comparison treatment of papain meat tenderizer or vinegar. Pain was measured at 0, 2, 4, 6, 8, 10, 15, and 20 minutes using a 10-cm visual analog scale (VAS). For 25 subject runs, the average VAS scores at t = 0 were 3.6 cm (hot water) and 3.7 cm (comparison treatment). At t = 4 minutes (2 minutes after treatment had started), the differences between hot-water and comparison group VAS scores were 2.1 cm versus 3.2 cm, respectively. The mean difference between hot-water and comparison treatments was 1.1 cm (95% confidence interval, 0.6 to 1.6). At t = 20 minutes (the end of the study period), the differences between hot-water and comparison group VAS scores were 0.2 cm versus 1.8 cm, respectively. The mean difference between hot-water and comparison treatments was 1.6 cm (95% confidence interval, 0.9 to 2.3). This study suggests that the most efficacious initial treatment for C alata jellyfish envenomation is hot-water immersion to the afflicted site.
Acetic Acid↗
Marine antivenoms.
There is an enormous diversity and complexity of venoms and poisons in marine animals. Fatalities have occurred from envenoming by sea snakes, jellyfish, venomous fish such as stonefish, cone snails, and blue-ringed octopus. Deaths have also followed ingestion of toxins in shellfish, puffer fish (Fugu), and ciguatoxin-containing fish. However antivenoms are generally only available for envenoming by certain sea snakes, the major Australian box jellyfish (Chironex fleckeri) and stonefish. There have been difficulties in characterizing the toxins of C. fleckeri venom, and there are conflicting animals studies on the efficacy of C. fleckeri antivenom. The vast majority of C. fleckeri stings are not life-threatening, with painful skin welts the major finding. However fatalities that do occur usually do so within 5 to 20 minutes of the sting. This unprecedented rapid onset of cardiotoxicity in clinical envenoming suggests that antivenom may need to be given very early (within minutes) and possibly in large doses if a life is to be saved. Forty years of anecdotal experience supports the beneficial effect of stonefish antivenom in relieving the excruciating pain after stonefish spine penetration. It remains uncertain whether stonefish antivenom is efficacious in stings from spines of other venomous fish, and the recommendation of giving the antivenom intramuscularly needs reassessment.
Animals↗
Jellyfish responsible for Irukandji syndrome.
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Animals↗
Cardiovascular actions of the venom from the Irukandji (Carukia barnesi) jellyfish: effects in human, rat and guinea-pig tissues in vitro and in pigs in vitro.
1. We have investigated the cardiovascular pharmacology of the crude venom extract (CVE) from the potentially lethal, very small carybdeid jellyfish Carukia barnesi, in rat, guinea-pig and human isolated tissues and anaesthetized piglets. 2. In rat and guinea-pig isolated right atria, CVE (0.1-10 microg/mL) caused tachycardia in the presence of atropine (1 micromol/L), a response almost completely abolished by pretreatment with tetrodotoxin (TTX; 0.1 micromol/L). In paced left atria from guinea-pig or rat, CVE (0.1-3 microg/mL) caused a positive inotropic response in the presence of atropine (1 micromol/L). 3. In rat mesenteric small arteries, CVE (0.1-30 microg/mL) caused concentration-dependent contractions that were unaffected by 0.1 micromol/L TTX, 0.3 micromol/L prazosin or 0.1 micromol/L omega-conotoxin GVIA. 4. Neither the rat right atria tachycardic response nor the contraction of rat mesenteric arteries to CVE were affected by the presence of box jellyfish (Chironex fleckeri) antivenom (92.6 units/mL). 5. In human isolated driven right atrial trabeculae muscle strips, CVE (10 microg/mL) tended to cause an initial fall, followed by a more sustained increase, in contractile force. In the presence of atropine (1 micromol/L), CVE only caused a positive inotropic response. In separate experiments in the presence of propranolol (0.2 micromol/L), the negative inotropic effect of CVE was enhanced, whereas the positive inotropic response was markedly decreased. 6. In anaesthetized piglets, CVE (67 microg/kg, i.v.) caused sustained tachycardia and systemic and pulmonary hypertension. Venous blood samples demonstrated a marked elevation in circulating levels of noradrenaline and adrenaline. 7. We conclude that C. barnesi venom may contain a neural sodium channel activator (blocked by TTX) that, in isolated atrial tissue (and in vivo), causes the release of transmitter (and circulating) catecholamines. The venom may also contain a 'direct' vasoconstrictor component. These observations explain, at least in part, the clinical features of the potentially deadly Irukandji syndrome.
Animals↗
Irukandji Syndrome: what nurses need to know.
Irukandji Syndrome can be frightening for the patient and make care delivery difficult for the nurse. Nurses' knowledge of Irukandji Syndrome has been limited to information provided by marine biologists, doctors, and tropical medicine specialists. This paper proposes to assist with the evolution of nursing knowledge for the care of the patient with Irukandji Syndrome. An algorithm of nursing management is presented that has been derived from the continuing debate among scientists about the etiology of signs, symptoms, and treatment rationales. Community safety and education surrounding Irukandji Syndrome requires concurrent progression of nursing knowledge and scientific inquiry.
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A randomized, controlled field trial for the prevention of jellyfish stings with a topical sting inhibitor.
BACKGROUND: Jellyfish stings are a common occurrence among ocean goers worldwide with an estimated 150 million envenomations annually. Fatalities and hospitalizations occur annually, particularly in the Indo-Pacific regions. A new topical jellyfish sting inhibitor based on the mucous coating of the clown fish prevents 85% of jellyfish stings in laboratory settings. The field effectiveness is unknown. The objective is to evaluate the field efficacy of the jellyfish sting inhibitor, Safe Sea. METHODS: A double-blind, randomized, placebo-controlled trial occurred at the Dry Tortugas National Park, FL, USA and Sapodilla Cayes, Belize. Participants were healthy volunteers planning to snorkel for 30 to 45 minutes. Ten minutes prior to swimming, each participant was directly observed applying a blinded sample of Safe Sea (Nidaria Technology Ltd, Jordan Valley, Israel) to one side of their body and a blinded sample of Coppertone (Schering-Plough, Kenilworth, NJ, USA) to the contralateral side as placebo control. Masked 26 g samples of both Safe Sea SPF15 and Coppertone SPF15 were provided in identical containers to achieve 2 mg/cm(2) coverage. Sides were randomly chosen by participants. The incidence of jellyfish stings was the main outcome measure. This was assessed by participant interview and examination as subjects exited the water. RESULTS: A total of 82 observed water exposures occurred. Thirteen jellyfish stings occurred during the study period for a 16% incidence. Eleven jellyfish stings occurred with placebo, two with the sting inhibitor, resulting in a relative risk reduction of 82% (95% confidence interval: 21%-96%; p= 0.02). No seabather's eruption or side effects occurred. CONCLUSIONS: Safe Sea is a topical barrier cream effective at preventing >80% jellyfish stings under real-world conditions.
Administration, Cutaneous↗
A probable case of Irukandji syndrome in Thailand.
The Irukandji syndrome is a jellyfish envenomation caused by Carukia barnesi or related jellyfish. In literature, the distribution of "Irukandji-like" syndromes is restricted to Australia. We report a case of probable Irukandji syndrome in Thailand. With this report, we hope to promote awareness to aid sting prevention and stimulate research.
Animals↗
Early experience with magnesium administration in Irukandji syndrome.
The administration of magnesium sulphate is a proposed novel therapy for Irukandji syndrome'. In this non-randomized, unblinded case series, data from ten patients who received magnesium salts are reviewed. Magnesium sulphate boluses of 10 to 20 mmol, in the six patients for which there was adequate data, reduced pain scores immediately after administration from 8.7+/-1.5 to 2.8+/-2.8 (Wilcoxon rank-sum test, P=0.03). In ten patients blood pressure decreased with a mean difference of -18 mmHg in mean arterial pressure. Magnesium requirements in individual patients varied markedly. Pain on injection occurred in four patients, three of whom had received peripherally administered magnesium chloride, and one patient reported transient ptosis after administration of magnesium sulphate 166 mmol over 18 hours in the setting of severe Irukandji syndrome. Magnesium sulphate administration appears to attenuate pain and hypertension in Irukandji syndrome and warrants further evaluation in this setting.
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Reported knowledge, perceptions, and behavior of tourists and North Queensland residents at risk of contact with jellyfish that cause the "Irukandji syndrome".
OBJECTIVE: To determine the knowledge, beliefs, and behavior of local residents and visitors to North Queensland who may be at risk of contact with "Irukandji" jellyfish. METHODS: Structured interviews were conducted with 208 ferry passengers (92.9% response) traveling between Magnetic Island and Townsville (19 degrees S). RESULTS: A total of 88.1% of the locals, 69.8% of the domestic tourists, and 34% of the international tourists knew what an Irukandji was (P < .001). Half of the international tourists, 20% of the domestic tourists, and 3.9% of the locals with this knowledge incorrectly assumed it was safe to swim inside stinger-resistant enclosures or were unsure (P < .001). Visitors to Magnetic Island who had swum or intended to swim in the sea (47%) knew less about Irukandji than other visitors (P = .05). Only 42.3% of the respondents realized that Irukandji posed a risk to swimmers on the outer reefs, and only 33.1% knew that Irukandji were also found outside North Queensland. CONCLUSIONS: International tourists had little knowledge about Irukandji. Thus, accurate educational messages may need to be targeted at this group. Offshore water sport and reef tour operators should be encouraged to provide clients with protective clothing to minimize the risk of stings. A coordinated educational response across northern Australia may be necessary to inform the public about both the box jellyfish (Chironex fleckeri) and Irukandji.
Adolescent↗
Efficacy of a jellyfish sting inhibitor in preventing jellyfish stings in normal volunteers.
OBJECTIVE: To evaluate the protective effects of a jellyfish sting inhibitor formulated in sunscreen lotion vs conventional sunscreen against Chrysaora fuscescens and Chiropsalmus quadrumanus jellyfish. METHODS: Twenty-four healthy subjects at 2 research sites were randomly assigned to receive the jellyfish sting inhibitor (Nidaria Technology Ltd, Jordan Valley, Israel) to one forearm and conventional sunscreen to the other arm in a blinded fashion. Subjects were stung with jellyfish tentacles on each forearm for up to 60 seconds. Erythema and pain were assessed at 15-minute intervals over a 2-hour period. RESULTS: In the C. fuscescens group, all 12 arms pretreated with conventional sunscreen demonstrated erythema, and all subjects noted subjective discomfort. In contrast, no arm pretreated with the jellyfish sting inhibitor had objective skin changes (P < .01). Two subjects noted minimal discomfort in the arm treated with the sting inhibitor (P < .01). In the C. quadrumanus group, discomfort was reported in 3 of the 12 inhibitor-treated arms compared with 10 of the 12 placebo-treated arms (P < .05). Erythema was noted on 1 arm treated with the inhibitor and 9 arms treated with the placebo (P < .01). CONCLUSIONS: The jellyfish sting inhibitor prevented sting symptoms of C. fuscescens jellyfish in 10 of 12 subjects and diminished the pain of the jellyfish sting in the remaining 2 subjects. The jellyfish sting inhibitor also inhibited the more severe sting of the C. quadrumanus jellyfish in the majority of subjects. The jellyfish sting inhibitor does not eliminate the sting from C. fuscescens or C. quadrumanus jellyfish but significantly reduces the frequency and severity of stings.
Administration, Cutaneous↗
A review of venomous animal bites and stings in pregnant patients.
This is a review of Medline and PubMed articles on venomous animal bites and stings during pregnancy reported in English literature from 1966 to 2002. Eighty-five venomous snakebites were reported in pregnant women. Although there are frequent anecdotal reports of scorpion stings in pregnant women, few case reports are documented. Other venomous animal bites or stings to pregnant women that have been reported include spiders, jellyfish, and insects, and these are described. Adverse reproductive and teratogenic effects of venoms on gravid animals are also briefly reviewed. Although uncommon, venomous bites and stings during pregnancy may have significant adverse effects on the fetus and the mother.
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Muscle organization of the cubozoan jellyfish Tripedalia cystophora Conant 1897.
The musculature of the cubomedusa Tripedalia cystophora was investigated using immunohistochemical staining with an anti-actin antibody and histochemical staining with fluorescent phalloidin. The subumbrella is lined with a sheet of circular, striated muscle that is interrupted at the perradii, and by the nerve ring. The sheet is continuous with circular, striated muscle of the velarium, which turns radially on each face of the four velarial frenula. Perradial strips of smooth muscle run radially from just above the level of the rhopalia into the manubrium and lips. The strips give off perpendicular offshoots that run a short distance in parallel with the circular swim muscle. Musculature of the tentacles and pedalia is longitudinal and limited to the oral side of the pedalia. The pedalial muscle connects with bundles of smooth muscle that runs circularly from the tentacle base well into the subumbrella. The arrangement of striated muscle in the frenula suggests that these structures may function in directional nozzle formation of the velarium during turning. In addition, the perpendicular branching of the radial strips and the circular extensions of pedalial muscle may function in hinge formation to aid bending of the pedalia and tentacles into the subumbrella during feeding and protective responses.
Animals↗
The Gove chirodropid: a box jellyfish appearing in the "safe season".
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Animals↗
Temperature effects on box jellyfish venom: a possible treatment for envenomed patients?
OBJECTIVE: To determine the effect of temperature on lethality of venom from Chironex fleckeri (the potentially fatal box jellyfish). DESIGN: Venom extracted from nematocysts of mature Chironex fleckeri specimens was exposed to temperatures between 4 degrees C and 58 degrees C for periods of two, five or 20 minutes, and then injected into freshwater crayfish (Cherax quadricarinatus) to assess lethality. MAIN OUTCOME MEASURE: Venom lethality, assessed as time to cardiac standstill in crayfish after intramuscular injection. RESULTS: Venom lethality was significantly affected by both temperature (F(7,34) = 21915; P < 0.0001) and time of exposure (F(2,34) = 9907; P < 0.0001). No significant loss of lethality was seen after exposure to temperatures or= 43 degrees C, venom lost its lethality more rapidly the longer the exposure time. Venom was non-lethal after exposure to 48 degrees C for 20 minutes, 53 degrees C for five minutes, and 58 degrees C for two minutes. CONCLUSION: Exposure to heat dramatically reduces the lethality of extracted C. fleckeri venom. Although heat application may be of limited use in treating C. fleckeri envenoming because of the speed of symptom onset, its use in other box-jellyfish envenomings, such as Irukandji syndrome, requires investigation.
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Jellyfish envenoming syndromes: unknown toxic mechanisms and unproven therapies.
Interest in envenoming syndromes caused by Australian jellyfish has been intense since the deaths in early 2002 of two tourists in Queensland, attributed to the Irukandji syndrome. We review current knowledge of these envenoming syndromes, mechanisms of venom action and therapy, focusing on the deadly box jellyfish, Chironex fleckeri, and the array of jellyfish thought to cause the Irukandji syndrome. Current understanding of jellyfish venom activity is very limited, and many treatments are unproven and based on anecdote.
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Severity of Irukandji syndrome and nematocyst identification from skin scrapings.
OBJECTIVES: (1) To identify the causative jellyfish species by examining skin scrapings in patients presenting to Cairns Base Hospital with marine stings, and (2) to describe clinical outcomes of those with Irukandji syndrome and those in whom nematocysts were identified from skin scrapings. DESIGN AND SETTING: (1) A retrospective case series of 128 patients, identified from Cairns Base Hospital emergency department records with discharge diagnoses of marine stings between 1 July 2001 and 30 June 2002. (2) A prospective study of skin scrapings from 50 patients presenting with marine stings from the same period. MAIN OUTCOME MEASURES: Number of patients with Irukandji syndrome, their opioid requirements and cardiac findings (where available); identification of causative species from nematocysts isolated from skin scrapings. RESULTS: 116 patients retrospectively identified with marine stings had Irukandji syndrome. Of 50 patients who had skin scrapings, 39 had nematocysts consistent with Carukia barnesi. Symptoms experienced ranged from local pain alone to severe Irukandji syndrome with elevated troponin I levels, changes on electrocardiogram, cardiac dysfunction on echocardiography, and high opioid dose requirements. One patient had an unidentified cnidome on his skin scraping. He developed severe Irukandji syndrome and subsequently died from its complications. CONCLUSION: This is the first published report of Carukia barnesi being successfully identified from skin scrapings. Most patients with identifiable cnidomes experiencing Irukandji syndrome were stung by Carukia barnesi, which we show causes a wide range of illness, including cardiac dysfunction. Our finding of a cnidome not consistent with Carukia barnesi in the setting of Irukandji syndrome makes it possible that other species of jellyfish may also cause this syndrome.
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