Jellyfish and Stings
Jellyfish injuries occur when people accidentally come into direct contact with jellyfish tentacles. The stinging structures on the tentacles are called nematocysts, which are spring-loaded venom glands that contain small, hollow, sharp tubes. The tubes release toxin. The nematocysts are triggered by direct physical contact or abrupt changes in osmolarity (such as exposure to fresh water). When exposed skin comes into contact with a jellyfish, poison is injected into the outermost layers, causing the toxic reaction of a typical sting. Some types of jellyfish, especially the box jellyfish and the Portuguese man-of-war, cause stings that are more toxic than others.
Jellyfish are invertebrate marine animals. There are nearly 9,000 species of jellyfish, which can be broken down into 3 main classes:
- The hydrozoans include feathery hydroids, fire coral, and the Portuguese man-of-war
- True jellyfish (scyphozoans) are the most common species of jellyfish in North America. As a rule, their stings are considerably less toxic than the hydrozoans and are usually limited to eruptions of the skin where contact took place. The box jellyfish, however, is an exception.
- Sea anemones and corals (anthozoans) are also related to jellyfish but are usually minimally poisonous.
Skin reactions
- Most jellyfish stings result in a painful, raised, red rash that itches, usually limited to the area of direct contact.
- Lesions can last for days to weeks. Severe stings can result in skin sloughing (peeling off) and deep wounds.
- Sometimes, an allergic reaction can occur in response to the initial sting, which can lead to swelling and further inflammation of the skin.
- The thimble jellyfish, can release eggs that can lodge within swimwear (sometimes referred to as “sea lice”). A rash occurs on the skin under the swimwear and usually develops during the first 24 hours and lasts for up to 5 days.
- Rarely, severe jellyfish stings can cause weakness, headaches, vomiting, muscle spasms, fevers and chills, and difficulty with breathing, and even shock.
- Stings from the box jellyfish of Australia have been known to cause sudden death.
- Remove the victim from the water.
- Rinse the affected area with salt water or don’t rinse it at all. Do not rinse the involved area of skin with fresh water, because it will further activate nematocysts and worsen the reaction. [rinsing with fresh water is one of the most common mistakes made by divers]
- Using protective gloves or forceps, remove any tentacles still in contact with the victim. Tentacles should be lifted off the skin (don't scrape them off -- this causes further stings)
- Apply acetic acid 5% (white vinegar). This will inactivate undischarged nematocysts and the toxin and will help to decrease symptoms.
- Symptoms of pain can be treated with topical anesthetics such as those generally contained in sunburn preparations
- Immobilize the area that was poisoned to prevent further spread.
- If the victim appears ill, revert to primary and secondary emergency care and call EMS.
- Wear exposure protection – full length wetsuits or lycras are recommended.
- Cover all areas of skin not covered by an exposure suit with a healthy layer of waterproof sunscreen – this will create a better-than-nothing layer between your skin and nematocysts.
- Avoid passing through surface debris, such as seaweed or leaves that may be harboring jellyfish.
- PAY ATTENTION to your surroundings – move if you see what appears to be “fishing line” in the water, it could be tentacles from a jellyfish out of your direct view
- DON’T TOUCH – jellyfish, corals, and sea anemones really aren’t on the attack!
