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September 2003 Vol. 18, No. 9   RSS Feed for Undercurrent Issues
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Getting Nailed by Jellies

a commercial preventative lotion proves effective

from the September, 2003 issue of Undercurrent   Subscribe Now

More than 13,000 species of corals, anemones, hydroids, and jellyfish can make your life an itchy, painful nightmare -- and even kill.

Members of the phylum Cnidaria, these animals have capsule- shaped cells with a trapdoorlike lid, containing a stinging nematocyst. A poison sac with an attached hollow filament armed with barbs, this sharp thread can be propelled into the skin at the speed of a bullet. The cell injects a viscous mixture into the skin where it can enter general circulation. The venom has both toxic and immune system activity.

A nematocyst typically fires as the result of friction, such as brushing up against fire coral or stinging hydroids, bumping into a jellyfish, or getting thimble jelly larvae between you and your suit. The transition from a saltwater dive to a freshwater shower, or drying off during a surface interval, also can cause the nematocyst to release.

Most affected divers develop localized, itchy red welts or blotches that may appear instantaneously -- jellyfish stings -- or up to 24 hours after diving -- delayed sea bather's eruption from thimble jelly larvae (a.k.a. "sea lice"). The skin disorder usually resolves within a week, but may linger, and can return several weeks later. In severe cases, blisters develop and areas of skin die and slough off, even leaving long-lasting skin discoloration or scarring.

Some divers may develop fever, headache, nausea, difficulty in swallowing or breathing, faintness, rapid heart beat, weakness, chills, diarrhea, and muscle spasms. The Portuguese man o' war, whose tentacles can reach a staggering 100 feet and contain millions of nematocysts, and Irukandji jelly are especially nasty characters. The Irukandji, which inhabits the waters of northern Australia, has caused 67 recorded deaths. The Portuguese man o' war is far less lethal, but its stings are so excruciatingly painful that life can seem worse than death.

It is helpful to check with local health agencies or inquire at your resort and dive op about the current prevalence of stinging creatures. If they are aware of heavy infestation of free-swimming stinging creatures, you can always skip the scuba. If you do go, wear a well fitting, full body protective suit that fits snugly at the neck, wrists, and ankles. When doing a night dive, turn off your light at the safety stop and keep it off. Upon surfacing, remove garments immediately and rinse yourself first in saltwater, then in fresh.

SafeSea, applied before getting stung, substantially
reduced both pain and skin reactions from
contact with the jellyfish tentacles.

You can also slather yourself with SafeSea before each dive. Developed by an Israeli marine biologist, Amit Lotan, Ph.D., and colleagues at Nidaria, Ltd., it protects against the stings of many jellyfish, fire coral, and thimble jelly and anemone larvae.

The product is ingeniously based on the chemical properties of the coating that protects clown fish from being stung by the anemones they inhabit. It is designed to keep nematocysts from being activated and has both research and anecdotal reports of effectiveness. The product has been evaluated at many sites, including last year at California's Stanford University. Volunteers' forearms were exposed to envenomation by sea nettle jellyfish (Chrysaora sp.). SafeSea substantially reduced both pain and skin reactions resulting from contact with the tentacles. Only 17 percent of the subjects treated with Safe Sea reported discomfort, while all those in the placebo group reported pain. Concurrently, observable signs of skin irritation as assessed by a dermatologist were significantly less in the SafeSea group.

Japanese researchers have looked at SafeSea's ability to protect against many jellyfish, including the Pacific Caribdea and Chiropsalmuse box jellies. While most of the subjects using regular sun screen developed inflammation after a sting, 80 to 100 percent of the subjects covered with SafeSea did not have a skin reaction.

Just completed was clinical testing at the Bert Fish Medical Center in New Smyrna Beach, FL. The product reportedly proved largely successful against the sting of the sea wasp (Chironex fleckeri), a type of box jelly. However, specific results cannot yet be released as Dr. Lotan, Nidaria's chief technical officer, indicated that they have submitted the study to a scientific medical magazine and are awaiting review.

When asked about its effectiveness against thimble jelly larvae, Dr. Lotan said that because of these creatures' small size and relatively small number of stinging cells, SafeSea can provide excellent protection. He stated that anecdotal reports gathered from swimmers and surfers in Florida over the past four years have been positive. Apparently, the tiny size of sea lice makes it difficult to conduct clinical tests, but the company is developing a protocol to assess SafeSea's protection level against them under controlled conditions.

In any event, because the lotion is not 100 percent effective, one should take the other preventive steps discussed here.

If you do get stung, there are a few self-remedies that are most effective when done immediately upon realizing that you've been stung.

o For a jellyfish sting, first remove any graspable tentacles; then use shaving cream and a razor to shave away any remaining particles. A sand-and-seawater paste and a credit card, or even a sharp-edged shell, will work.

o Apply pure vinegar to the affected areas. If unavailable, use isopropyl alcohol (rubbing alcohol) or Windex. Repeat this several times during the first 30 minutes after the sting. Be aware, however, that these treatments can cause the nematocysts of certain jellyfish to fire, such as those of the Portuguese man o' war and lion's mane (Cyanea capillata). It is prudent not to apply them if you have a known or suspected envenomation by these creatures.

o Alternatively, apply a thin poultice of meat tenderizer and allow it to dry.

o Bathe in or apply colloidal oatmeal.

o Follow these actions with the topical application of hydrocortisone (prescription strength preferred). You may substitute Benadryl lotion or a calamine preparation with menthol, but these are less effective.

o Use OTC or prescription analgesics to control pain.

o If the allergic reaction is pronounced and you can take an oral antihistamine such as Claritin, consider doing so, although some of these drugs cause drowsiness and may be unsafe for use while diving.

If you don't get resolution from self-treatment, the allergic reaction is severe, or the eruption gets worse or infected, seek medical attention.

P.S.: SafeSea can be found in some dive shops and pharmacies, or ordered online at many sites such as Nidaria Technology, Ltd., ( or Solar Tan Thru at (

Pee Pee S: While you have no doubt heard that peeing on a jellyfish sting will help, a number of respectable dive medicine/dermatology experts think it an old wive's tale and may, in fact, cause nematocysts to fire. Additionally, if one has a urinary tract infection (women are particularly susceptible to occult UTIs), the urine could introduce bacteria into the wound.

-- Doc Vikingo

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