Here's everything you need to know about jellyfish including how to get rid of the pain from a sting.

First of all, those clinging jellyfish you've been hearing about in the bays and rivers are rare and prefer to spend their days “clinging” to underwater plants in shallow, sheltered waters, so an encounter in the ocean, or any area heavily used by swimmers for that matter, is highly unlikely.

But how about the jellyfish that do share the Atlantic Ocean with us? Yes, some can sting, but severity varies greatly. Those gelatinous, undulating creatures we call jellyfish (despite the fact that they are definitely not fish) all produce at least some toxin, but not every species is dangerous to humans. What to do if you are stung? More on that later but here’s a hint—don’t pee on it.

Jellyfish can be up to 98% water, have no backbone, brain or heart, and perhaps most disturbing, they eat and poop using the same orifice. Several types are common in New Jersey’s coastal waters:

The moon jelly has thread-like tentacles attached under its bell-shaped body but its sting is not powerful enough to pierce human skin. The well-named mushroom cap jelly is also not hazardous. It is creamy white with darker markings on its firm, stem-like group of tentacles, making it look very much like an aquatic mushroom. Then there are comb jellies. Also harmless, these simple creatures are lined with rows of tiny beating hairs or cilia which propel them through water. They do not sting, and at night, if stirred up—maybe by a wave or the wake of a boat-- they glow in the dark!

Technically not a jellyfish, another harmless, common jelly-like New Jersey native is the hydromedusae. Frequently seen washed up on shore, they appear at first as a clear, round glob. Since they are mostly water, they soon dry up leaving behind a flat, sand-dollar sized brittle disk. They are safe to handle (but really, why?) since the surf has already washed away their tentacles.

Moving into more dangerous territory, the red or lion’s mane jellyfish can grow tentacles up to 200 feet long. The purple jellyfish has five tentacles surrounding its mouth which is used for feeding, and, as we learned previously, pooping. Both can give you a nasty sting and should be avoided.

Lastly, there is the annoying sea nettle and the downright creepy salp:

Sea nettles can give you a nasty sting but generally confine themselves to estuarine waters. In recent years, they have been real problems in Barnegat Bay due to overabundance, but there may be a bright side—they’ve been known to eat clinging jellyfish.

Salps are not jellyfish at all, or even fish eggs, but they link together by the thousands to form gelatinous, clear chains that, to put it mildly, can be off-putting to swimmers. Their life history is also peculiar. Each one starts life as a female, then switches to male and never switches back, but no one knows why.

WHAT TO DO IF YOU ARE STUNG BY A JELLYFISH: First, return to dry land as soon as possible to avoid getting stung again. Once you are on land, don’t pee on it. This is a total myth, perhaps perpetuated by a Friends episode where Chandler pees on Monica. Don’t rinse off with fresh water—use salt water which you’ll have in abundance. Fresh water can cause the cells that stung you to release more venom and this means more pain. Also try rinsing with vinegar—white vinegar is best. Vinegar has acetic acid which helps relieve pain. Shaving cream might work too. After rinsing, scrap away remaining tentacles with a stiff, blunt object such a credit or debit card, then apply hot water or a hot pack as hot as you can stand it for 20 minutes. In very rare cases, a jellyfish sting might cause vomiting, headaches or seizures. If that is the case, seek immediate medical attention.

For more about clinging jellyfish CLICK HERE.

For a comprehensive guide to NJ Jellyfish CLICK HERE.

And for more info about everything in our sea, check out the NJ Sea Grant Consortium, which has provided all of this fantastic information!