sting – BioGeoPlanet

We like to snorkel in tropical waters throughout the world and, as biologists, we’ve learned to be cautious when it comes to jellyfish. Not only are jellyfish stings painful; some species can kill you! In this article I will explore some of the latest scientific findings on one of the most dangerous groups of jellyfish – the Irukandji. Irukandji are tiny transparent jellyfish that cause the painful, and potentially life-threatening, Irukandji syndrome. They are less than 1 inch (approximately 2 cm) in diameter with 4 tentacles that can reach up to 3 feet (one meter) in length. Due to its small size these jellyfish can sting people even inside net enclosures. Researchers have discovered up to 25 species of Irukandji-type box jellyfish throughout the world. Carukia barnesi is commonly referred to as the Irukandji jellyfish, as this was the first species, identified in 1952, found to cause Irukandji syndrome. Other notable species that also cause this painful condition include Alatina mordens, Malo maxima, Carybdea alata, Carybdea xaymacana, and Carybdea rastonii. Irukandji-type box jellyfish are about the size of a sugar cube and can be particularly dangerous to swimmers and snorkelers because they are so tiny and almost transparent in ocean water. Malo kingi in a clear plastic vial. Wikimedia International visitors to tropical settings, especially Australia and South-east Asia, are often unaware of the dangers posed by the various species of box jellyfish, including the tiny Irukandji. Hopefully, this article will help travelers understand the potential risks, so they can prepare accordingly. Headline in a British newspaper warning of the threat posed by Irukandji. Irukandji jellyfish (Carukia barnesi). Photo by Lisa-Ann Gershwin CC BY 4.0 Irukandji adaptations The key to the Irukandji’s success over hundreds of millions of years is the venom packed nematocyst or stinging cell. Stinging cells are pressurized structures that fire a tiny, barbed harpoon into predators and prey, injecting a painful and paralyzing venom. Even though the Irukandji is tiny, it is covered with many thousands of stinging cells, as are most species of jellyfish. Unlike most other jellyfish species, C. barnesi has nematocysts on the bell as well as the tentacles. Nematocyst structure and mechanism, from Montgomery et al, 2016. Using high-speed cameras, researchers have found that the discharge of the tiny harpoon takes place in about 700 ns (0.0000007 s), which makes it one of the fastest biological events ever measured. Nematocyst discharge in slow motion What makes the Irukandji-type box jellyfish especially dangerous is the lethal power of the venom it manufactures in its tissues. Like many box jellies, Irukandji-type jellyfish are active hunters feeding on fish, even though they are so small. To successfully kill fish, they need an extremely powerful venom that kills with even in tiny doses. The venom of the Irukandji is considered to be one of the most powerful toxins in the natural world. Dr Robert Courtney, James Cook University, is a leading expert on the complicated lifecycle of the Irukandji jellyfish: Carukia barnesi. While observing Irukandji in seawater tanks in his laboratory, he has uncovered the amazing story of how they are actively fishing. “We had thought these animals were swimming around haphazardly collecting prey,” he writes, “but the opposite was happening.” Dr. Courtney has observed the jellyfish extending and twitching their tentacles in the water to attract specific sizes and species of larval fish. “We have a jellyfish that is essentially jigging for fish with its tentacles, mimicking something else, and small fish are seeing this as a food source and getting a face-full of venom,” said Dr Courtney. Adult Irukandji actively attract larval fish with their tentacles and lure-like nematocyst nodes, and proceed to sting and consume the fish. Watch the video below with Dr. Courtney explaining his groundbreaking research. Irukandji actively hunt and kill fish The fish (Acanthochromis sp.) was captured by a twitching tentacle of an adult Carukia barnesi. The bell size of this specimen is approximately 15 mm in height and the fish is approximately 10 mm in length. Note the envenomation site is on the head region of the fish. Screenshot of video from Courtney et al, 2015. Irukandji syndrome Irukandji syndrome is an extremely painful, potentially lethal condition caused by tiny jellyfish within the class Cubozoa (box jellyfish). Although the initial sting is comparatively mild, usually less painful than a bee sting, after 10 to 40 minutes the ensuing symptoms become much more serious and potentially life-threatening. These can include severe pain, muscle cramping, vomiting, and breathing difficulties. In a small number of cases, life threatening hypertension, pulmonary oedema, and cardiac complications may develop. One notable symptom is a feeling of “impending doom.” Currently, there is no antivenom available. Dr. Lisa-Ann Gershwin, one of the world’s leading authorities on Irukandji jellyfish and author of the must-read book Stung: On jellyfish blooms and the future of the ocean, describes the symptoms like this: “It gives you incredible lower back pain that you would think of as similar to an electric drill drilling into your back. It gives you relentless nausea and vomiting. How does vomiting every minute to two minutes for up to 12 hours sound? Incredible. It gives waves of full body cramps, profuse sweating...the nurses have to wring out the bed sheets every 15 minutes. It gives you very great difficulty in breathing where you just feel like you can't catch your breath. It gives you this weird muscular restlessness so you can't stop moving but every time you move it hurts. It gives you a feeling of impending doom. Incredible. Patients believe they're going to die and they're so certain of it that they'll actually beg their doctors to kill them just to get it over with. And all of this from this little tiny jellyfish.” “It’s difficult to know how many victims the Irukandji have claimed,” writes well-known Australian biologist Tim Flannery, since “many deaths have doubtless been put down to stroke, heart attack or drowning.” Signs and Symptoms of Irukandji Syndrome PainLow back painGeneralized muscle painChest painAbdominal painCatecholamine ExcessSweating, localized or generalizedPiloerectionAnxiety (feeling of impending doom)RestlessnessNauseaTremorPallor or peripheral cyanosisTachycardiaOliguriaHypertensionCerebral edemaCardiopulmonary DecompensationAcute pulmonary edemaLeft ventricular dysfunctionFrom Gussow, Leon MD The Amazing and Bizarre Discovery of Irukandji Syndrome, Emergency Medicine News: April 2005 - Volume 27 - Issue 4 - p 44-45 The Irukandji syndrome was named in 1952 by Hugo Flecker, after the Aboriginal tribe living near Cairns, North Queensland, Australia. The jellyfish Carukia barnesi was named after Jack Barnes, the scientist who discovered the species responsible for the condition. In one of the more fascinating stories of medical discovery, Barnes established the causative relationship by placing an Irukandji jellyfish against his upper arm, along with that of his 9-year-old son and a local lifeguard. Within minutes all three began to suffer from severe back and abdominal pain, generalized muscle cramping, spasm, nausea and vomiting, and had to be rushed to hospital. Fortunately, all three survived the ordeal, thanks to opiate painkillers, and managed to recover completely within 24 hours. What to do if stung by an Irukandji Here is the latest medical advice for dealing with an Irukandji sting, as recommended by the Australian Resuscitation Council, the American Heart Association, and the Red Cross. Disclaimer: This information is not intended nor implied to be a substitute for up-to-date professional medical advice. For the latest first aid recommendations, consult the Australian Resuscitation Council (see Guideline 9.4.5). As most Irukandji stings will result in severe symptoms, you should alert emergency medical services as soon as possible, and have the patient transported to hospital. Respiratory failure can ensue, prompting the need for CPR, oxygen, non-invasive ventilation, or even endotracheal intubation.