Diving Safety — Ouch! Jellyfish
Of the 2000 varieties of jellyfish in the world, only 70 are harmful to humans. There is a famous site in Palau called Jellyfish Lake where you can snorkel with millions of Golden and Moon Jellyfish without being stung.
On the other extreme, some species such as the Box Jellyfish are lethal to humans, its sting so intensely painful that most victims suffer heart attacks or drown before even having the chance to get out of the water.
Occasionally you will encounter jellyfish diving, so wearing a full length suit or a log sleeved rash guard or sharkskin will help with protection against stings.
The sting comes from venom injected through a microscopic barb. Jellyfish tentacles are covered with cells called cnidoblasts, which contain nematocysts. Nematocysts are what give the jellyfish the power to knock out prey. The main food sources are smaller fishes, eggs and larvae of sea creatures and zooplankton. The larger species eat crustaceans and other jellyfish.
If you are unfortunate enough to get stung first use white vinegar to deactivate the nematocysts that may still be clinging to your skin. Then using tweezers remove any tentacles still on the wound. If tweezers are not available the person removing the tentacles should wear gloves to prevent being stung.
After removing the tentacles, immerse the affected arm or leg immediately in hot water at 40 to 45°C (104 to 113°F) for at least twenty minutes. A hot shower can be used instead for other parts of the body. If hot water is not available, cold packs or ice can be used instead.
If needed apply an anti-inflammatory such as Cortizone.
Most jellyfish stings just cause a minor irritation but when diving in some areas such as Australia where they have the Box it’s best to do your homework with the local dive operators.
Photo thanks to Branko