What the Heck is in the Water?

francis tube

There’s been a lot of talk around the island about some odd stinging organism that’s been hanging out in the water, particularly along the North Shore, over the past few days, perhaps even weeks. I hadn’t paid much attention to it because I hadn’t experienced it myself. Then Sunday happened…

After having a delicious breakfast in Coral Bay (I’ll have more on that later this week), I cruised on over to Francis Bay for a relaxing afternoon on the beach. I popped open an adult beverage, grabbed my cute little orange float and headed out into the water.

I was floating around enjoying the breathtaking views for about five minutes when all of a sudden I started to itch. The itching quickly turned into stinging and before I knew it, I had a big welt on the back of my leg. And then it started to hurt, like really hurt.

According to Gerald Singer, author of SeeStJohn.com and one of the most knowledgeable island residents when it comes to sea life and such, I most likely had the fortune of running into some stinging plankton. Here’s what Gerald wrote about it on his website Saturday:

“I took two nice long swims; one yesterday at Hawksnest and another, the day before at Trunk. I kept feeling these little stings, but didn’t see anything and the pain only lasted for a second or two, so I just kept on swimming. But now I have all these little bumps and they ITCH!!!

The probable culprit, a stinging plankton with the disgusting name “sea lice.” These tiny plankton, some so small that you can’t even see them, have a microscopic little barb called a nematocyst that activates when the plankton makes contact with something, like another plankton or small fish or you, and releases an irritating protein, that can develop into a itchy, itchy, itch later on.

I can attest to their presence at Hawknest and Trunk Bays and I’ve heard reports from Caneel Bay and even out on the East End, so it looks like they’ll be around for a while, until that evil tide or current that brought then this way takes them somewhere else. The sooner the better!

Treatment is a really hot shower, like as hot as you can stand it and then vinegar or a meat tenderizer paste to break down the protein. Helps a bit, but you can count on the itch coming back after a while. The itching usually lasts a few days to as much as a week.

I’ve found that this stuff you can get a Chelsea, Benadryl Itch Stopping Gel, is effective, at least for a time.

These plankton, along with other possible itchy-stingy organisms like jellyfish, for example, exist in the sea at all times, but usually in such small concentrations that that they won’t ever be a nuisance. Now apparently, there are enough of them around our bays to virtually guarantee an encounter.”

Now obviously I didn’t have any vinegar or meat tenderizer handy at the beach to help with the pain and itching Sunday afternoon. Luckily I do have a pretty smart island BFF who told me to rub some sand on it. I did and voilà! The pain and itching soon subsided.

So, the moral of this story is… Well I’m not really sure there is one. 🙂 The fact of the matter is that these little buggers are out there and they’re no fun. Should they stop you from going in the water? Probably not. But just be aware and maybe bring some vinegar with you the next time you head to the beach





31 thoughts on “What the Heck is in the Water?”

  1. The sea lice are quite common and I often encounter them while snorkeling. They are annoying but not painful.

    There are also Box Jelly fish and they are very painful. The only place I have seen them is in Little Lameshur in December. It is quite possible they are in other locations as well.

  2. My wife & I were on island in late-February and encountered these annoying little guys. We noticed it a few times at Trunk and Caneel, but worst was during a swim from Maho around the small point and over to Little Maho and then Francis. Couldn’t for the life of us figure out what they were because, as the post states, you can’t see ’em, so you can’t really identify & avoid ’em.

    Thankfully mine didn’t stay itchy for much more than a day but my wife had a couple noticeable welts on her legs with an itch that lasted a little longer, so they must affect certain people more than others (or maybe the meaner plankton just favored her!).

    Hopefully they move on so folks can enjoy all of St. John’s North Shore gems hassle-free. Happy snorkeling!

  3. We ran into these nasty buggers when we were down a few weeks ago as well.

    We got stung at Maho, Francis and even Oppenheimer. Fortunately the itching didn’t last too long for us. But the initial sting was quite sharp, and we both developed a couple of welts right after too. I did a little research when we got back and learned of these “ocean lice” or “stinging plankton.”

    From what I have read, based on the time of year, water temps and location, the specific type of zooplankton we likely encountered were the larval stage of thimble jellyfish. They typically float at/near the surface, and only sting when they get trapped or squeezed (frequently in/along bathing suits edges, snorkel gear etc). They are the size of fresh ground pepper, but clear. So they are impossible to see in the water.

    Best treatment is to get out of your suit while it’s still wet and then take a hot fresh-water shower. Then treat any welts with oatmeal or lotions designed to ease the discomfort of a bug bite or sting.

    The best way to avoid getting stung when they are around is to swim naked. No joke! Apparently, by avoiding getting them trapped in suit linings and waist bands you avoid the stinging. Guessing this is not an acceptable defense for public indecency,

    Obviously not an option on most beaches in St. John, but there are also a few lotions that can be applied ahead of getting in the water that claim to lessen the effect and likelihood of a sting (similar to a clown fish).

    It still couldn’t keep us out of the water, the snorkeling is just too good to pass up due to a few stings.

  4. The first thing to keep in mind is that a bad day on STJ is always better than a good day here at work in the States.

    I called Divers Alert Network (DAN) for their take on how to treat this. The first thing that she offered is prevention. A divers skin MAY help to prevent/limit your exposure. She said that since there are already reports of them getting under swim suits, this may not help. Another preventative treatment DAN did not offer is to stay firmly planted on a bar stool. They don’t call them Painkillers for nothing.

    The second step she talked about is immediate treatment. Bring a spray bottle (glass cleaner type bottle) filled with vinegar to the beach or boat. When you get out of the water, spray all surfaces that have been exposed (probably head to toe) to knock them off and stop the chemical reaction that hurts so much. Rinse that off in sea water (may not be practical because that is where the stinging little monsters are found) and rinse again with fresh water.

    The next step is a hot shower. The water should not be so hot that it is painful. DO NOT GET A BURN ON TOP OF THE STINGS. That will not be helpful. The heat helps clean the skin, improve circulation which promotes healing, and it will act as an analgesic and reduce pain. Complete the shower with vigorously toweling off. The physical action of the rubbing will help clean the skin further.

    Finally, treatment for the welts. hydrocortisone, Benadryl, calamine lotion, or anything else you would normally use to treat poison ivy or chigger bites will generally help.

    A serious case will require a doctor to prescribe steroids.

    That concludes our seminar. Drink up and get back out there.

    We will be arriving in two months. Clean up the water and do not use up all the fun before we get there.

  5. We were at Francis today – so many transparent things in the water it was like swimming in noodle soup! 1-2″ long ‘box strings” and tiny jelly fish with tiny orange centers. Very odd feeling…

  6. Why yes Karen rogers, by golly there is. Might I suggest going to Virgin Gorda and to The Baths and taking a dip in the water. I do believe time will tell. Good luck and let us know.

  7. We just returned from stj a week ago. We were traveling with a large group and several of us got stung several times at caneel and maho. We first felt a sting or even a sudden bite like from a mosquito followed by the itching. Luckily it didnt last too long but definately not fun. We have been going to stj for 12 years- usually in the month of april and have never experienced this before. We looked in the water very closely to try to figure out what the heck it was but assumed it must have been tiny jelly fish. Im glad i have an explanation now!

  8. We just returned from St John on Sunday. We have been visiting the island regularly since 1976 and this was the first time we have ever experienced this. We found them at Cinnamon and Francis, with Francis being so bad that my wife had to cut her snorkeling time dramatically. Her stings developed until welts/blisters. Mine re-surfaced on my arms 36 hours later on the drive from Miami airport to St Pete. Funny thing was the other couple we were with got stung but not much reaction. I suspect that people prone to allergies are impacted more severely. Benadryl gel works well to relieve the itch. I would suggest bringing along a tube if your headed to St John. The water and the snorkeling is too beautiful to avoid.

  9. Glad I found this forum. My husband and I arrived in STJ yesterday for our first visit here on our honeymoon. We felt the little stings in Francis Bay today, but luckily the pain didn’t last but a split second and we didn’t develop any welts or itching from the larval jellyfish. We’ll head out again tomorrow and see what happens. I figure it’s due to the warming of the oceans and the slight increase in acidity pH around the globe. When are the box jellyfish in full force around here?

  10. We were there from April 25-May 2 and snorkeled every day all over the island. The stings hurt pretty bad, but subsided after vigorously rubbing the area for 30 seconds or so. The ones caught on your lip hurt a bit worse and looked like the result of botox… They cut our snorkeling a bit shorter than we would have liked, but some areas were just too beautiful not to explore (stings or not). 3 days after we got back from St. John, my husband and I started showing raised bumps/rashes all over where we got stung (which was pretty much all of our skin not covered by board shorts, flippers, or shirt). If you forget not to itch it, it gets worse. We’re currently medicated with Solarcaine as it seems to numb the skin enough to forget it itches. Good luck all! It was worth it!

  11. We were in St. John/ St. Thomas from April 26 to May 4th. My husband, myself and two children got stung quite a bit at Trunk Bay, Honeymoon Beach, and Coki (most recently May 3rd). Itching like crazy today between the mosquito bites and little sea lice welts which keep popping up. The welts took a while to show themselves. Great time though! For the woman who asked about the Baths- we were there the 27th and didn’t encounter any sea lice or jellyfish.

  12. Finally! We went to Magens Bay during the carnival weekend. Heard a lady complaining about something biting her. I thought nothing of it and went in. About 5 minutes later my stomach started to itch, then my leg. What forced me out was when I got stung by what felt like when you get a slight electrical shock from touching something that shorting out. I spent the next few hours on the beach rubbing from my back to my legs. The next day i felt some burning at the back of my legs and thought I had gotten bite from some mosiqutos. I ended up wih huge welts which was red and itchy on both legs and some smaller ones on my thighs, stomach, arms and back. Its exactlye one week and the itching has finally stopped but the welts on the back on the back of my leg are smaller but still there. Glad to know what caused it. No more beach for me till summer which hopefully by then they will be gone.

    • Yes, they are still at some beaches. I’ve heard Francis is pretty bad. I have not personally seen them in more than a week.

    • As an update for anyone following — I just returned from a week long trip May 23-30th. They really aren’t so bad. We encountered them mostly when snorkeling out away from shore and not so much when in waist deep water. When they did get us it was a quick pintch/sting for 2-3 seconds then nothing afterwards.

    • Went to Maho yesterday, June 4, and they were terrible. Millions. They are like transparent worms, from tiny to 6 inches long. Some are totally transparent, some have black dots along their back. You can feel them, and can gather them in your hands in the shallow water. They were also at Trunk on June 3, but not nearly as many. Each person in my family of 8 reacted differently. My very healthy 46 year old son had the worst reaction. He became ill, with chest muscle pain, like the toxins got deeper than his skin and were poisoning him. Have heard from locals that they usually come in August, but the drought in May may have changed that. Vinegar definitely helps! And be sure to shower in hot fresh water and scrub hard. Launder any clothes and swim wear you were wearing in hot water and use a hot dryer. I may not go to a beach on St Johns again this trip. We are leaving June 13.

  13. i just got back from a week in st. john saturday may 23rd. my wife and i encountered these little underdeveloped jellyfish or sea lice on most of the north shore beaches. south haulover bay did not have any, so it was the best snorkeling we had on the island. also, we did a day trip to the indians and the baths. no jellyfish there either.

  14. Thanks for the info on this. Been on the island since 5/26 and leaving 6/9. They aren’t going to stop me from going in the water but it is very annoying. Maho bay is pretty bad as of thus week. Hawksnest I was hit a few times. You can feel them pass through your fingers as you wade near shore. I didn’t feel them as I went out further.

  15. We just had to leave Francis Bay because of these. We could feel them moving through our fingers. We left before it got too bad. They were all over. We can home and jumped in the pool and it seems all is well now.

  16. It should be noted that I have IDed several species. These are not actually “sea lice” which are a small jellyfish larva that gets between your skin and a swimsuit and itch like crazy. What we have going through – (YES THEYRE STILL HERE) are a handful (or more) of stinging Ctenophores and Siphnophores. These are mostly colonial animals that feed on other plankton. Unfortunately several species Ive seen sting – and yes its pretty painful! Species Ive IDed: Pteropod Creseis aciculate – Marrus orthocanna – Nanomia bijuga – Apolemia uvaria – Agalma elegant and the harmless and most abundant one – a species of “sea slap” that you will feel bumping into you – jelly like but harmless.

    • I forgot to mention that the stings are not long lived. Usually lasting only a few minutes. One of the species that I got stung by on the leg did leave a mark and does itch as its healing – three days later but mostly just painful for a few minutes. Rubbing sand does work by firing all the nematocysts at once (hurts like hell for a second but will work in the long run) vinegar and hot water will also work. Pee doesn’t work but if you’re into that…… 😉

  17. Thirteen of my family vacationed at StJ from July 5th to the 12th and encountered these stinging creatures our first day at Francis. We did not go back there. My 3 year-old great granddaughter was totally freaked out. Hawksnest, Cinnamon Bay and Lameshur were clear. Great time was had by all after the first beach experience.

  18. November 21, 2015

    Well guess what…..their still there. Our family was swimming Maho and Honeymoon beach. Everyone is effected differently. I myself have suffered about a week and it is not enjoyable. The bite get itchy then swells like a blister. Nothing has total taken it away. I do have allergies, I would be careful if you suffer from some type of allergy. the rest of my family had moments, but started to subside in a few days.

  19. Will be going to St John at the end of June. I see many posts from 2015 on sea lice. So far this year 2016 has anyone encountered them?

  20. Was just at Hawknest yesterday (6/12/19) and was snorkeling with my son. We swam left towards Caneel Beach and out to the rock point. At the rock point I ran into what I called a wall of Jellies. I promptly turned back and found the same multitude of jellyfish anytime we got more than 50 yards away from the rocks (deeper water). I definitely swam into/through them but never felt a sting. My son got one small sting on his neck. Once we got back to the Caneel Beach area they seemed to not be any. I am not sure what type of jellyfish these were. They didn’t look like moon jellyfish. They were 1/2” to 3” in diameter and seemed taller than wide and didn’t seem to swim much – they were just hanging in the water. There were LOTS of them to where you could not swim through/between them.

  21. Was just at Hawknest yesterday (6/12/19) and was snorkeling with my son. We swam left towards Caneel Beach and out to the rock point. At the rock point I ran into what I called a wall of Jellies. I promptly turned back and found the same multitude of jellyfish anytime we got more than 50 yards away from the rocks (deeper water). I definitely swam into/through them but never felt a sting. My son got one small sting on his neck. Once we got back to the Caneel Beach area there seemed to not be any visible jellyfish. I am not sure what type of jellyfish these were. They didn’t look like moon jellyfish. They were 1/2” to 3” in diameter and seemed taller than wide and didn’t seem to swim much – they were just hanging in the water. There were LOTS of them to where you could not swim through/between them.

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