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Jellyfish aren’t fish, and they aren’t made of jelly. They look like a blob of jelly when they are out of the ocean, and most species can give you a nasty sting. But in their natural habitat, they are a work of nature’s art.

The moon jellyfish is common to shorelines around the world, and often seen washed up on the beach, where it resembles nothing more than a transparent disc. It has short nonstinging tentacles and relies on ocean currents for movement. Here are some recipes, in case you have some fresh moon jellyfish.

Giant jellyfish can grow up to 6.5 feet wide and weigh 450 pounds! They’re edible, too.

The crystal jelly is a bioluminescent jellyfish. The transparent jellyfish produces green flashes of light chemically due to the green fluorescent protein that scientists use to study gene splicing. These experiments have led to the development of other glowing animals.

The Portuguese Man O’War may be the jellyfish you are most familiar with, but it’s not a jellyfish at all! It is actually a colony of specialized invertebrates that cling together to form one eating and reproductive being. The Man O’War floats on the surface of the ocean by filling its bladder with air. The tentacles hang down an average of three feet (but can reach 33 feet), and its sting is very painful and sometimes deadly to humans.

The fried egg jellyfish is native to the Mediteranian Sea and can grow up to 35cm wide. Most jellies depend on ocean currents for movement, but this one can swim on its own by flapping its dome. You can see it swim in this video.

There are many species of box jellyfish native to Australia, the Philippines, and other tropical areas. Some are not dangerous to humans, but one species, Chironex fleckeri, is the world’s most venomous animal. The sting from this particular species can cause death in minutes! If stung by a box jellyfish, apply vinegar before removing the tentacles, or it will inject more venom. That’s why Australians take vinegar along when swimming at some beaches during jellyfish season.

Jellyfish Lake on the island of Palau is a popular tourist destination. The lake was once connected to the sea, but became isolated by a reef. The jellies that were trapped in the lake thrived due to few predators. They have stinging tentacles, but they are so small that swimmers rarely feel any effects. Watch a video of the lake.
Jellyfish in motion, from National Geographic.
Cool… I’ve been Palau but never made it to the Jelly Fish Lake (closed by government). According to the island residents, the Jelly fish adapted to their new environment with humans and “lost its sting.” But I guess science won and they have tiny stingers that humans can’t feel. Hope to go there when I go back to Palau.
posted by Miss Nae on 11-6-2007 at 6:43 am
I despise jellyfish. Every year without fail since I was eight years old, I have been stung in the exact same spot by one of those loathsome creatures. I have finally decided that they are waiting for me to enter the water, plotting devious plans and rubbing their tentacles together in maniacal glee.
…I don’t go near the ocean anymore.
posted by bryn on 11-6-2007 at 7:52 am
bryn, I’m with you. On evening walks with my honey along the beach on vacation, I’m always the one to break the romantic mood, as I step squarely in the middle of a jellyfish that’s suicided on the beach.
Jellyfish are ugly and evil (peal of thunder-flash of lightning).
posted by Lalita on 11-6-2007 at 11:28 am
I lived in Taormina, Sicilia for a summer a few years ago… we went to this beach called something like Lido di Pirata and it was amazing… then we went to Isolabella… which because of the coves that go into the coast, collect jellyfish. Not amazing. It looked like soup, with golfball to baseball sized jellyfish in every inch of the water. Needless to say, we didn’t go in.
posted by Kelly on 11-6-2007 at 12:08 pm
Ugh…Man-o-war. That brings back painful memories.
posted by heather on 11-6-2007 at 12:33 pm
Is vinegar more effective than pee on a jellyfish sting? Or are they the same? I have (thankfully) never had the “pleasure” of being stung but I had always heard the pee thing and would like to be prepared just in case!
posted by GTT on 11-6-2007 at 12:49 pm
GTT, I read in several places that urine doesn’t help at all. Vinegar is only useful to make the tentacle let go; it doesn’t alleviate pain or neutralize the venom.
posted by Miss Cellania on 11-6-2007 at 1:08 pm
I lived in Hawaii for a while and there were tons of Portugese Man’o'Wars there. I got stung by one once but it must not have been for very long because it didn’t hurt all that much. I applied some meat tenderizer and was back in action in about thirty minutes. Seems like I grew up taught to be really afraid of all jellyfish but have not had very many bad experiences to back up the fear. Same goes with sharks too…. they are soooo much fun to swim with (mostly little ‘uns of course- I might be stupid but I don’t have a death wish).
posted by Celeste on 11-7-2007 at 2:56 pm
I live in Atlantic Canada, and we don’t have any deadly jellyfish here, just the Arctic Red Jellyfish, and their stings just..well..sting, and lately there have been bigger (averaging half a foot in diameter to 1 and a half feet) ones with longer tentacles compared to last summer. Sadly my first sting this summer was down in my shorts, which to say the least was uncomfortable since i dove into it and a tentacle came off and got stuck down there.
posted by Darcy on 7-26-2008 at 2:51 pm
In westerly, RI, jellies apear in anormous amounts in august. Mostly footwide man’o'wars and lions mane. But a rare occurance of box jelly have appeared, strangely attracted to the warmernwater in RI. I have found many remedies successful for these different stings. Please email!!!!!!!!!!!!!!
Kevin
MD
posted by kevin dbrain on 8-11-2008 at 12:35 pm