Last week my younger daughter’s birthday coincided with spring break so we all took a little time off and spent it having fun. One of our outings was to the Anchorage Museum to see the new Mammoths and Mastodons exhibit (find information here). While we were at the museum we had to pop in at the Imaginarium and that meant I could visit one of my favorite exhibits: the tank full of moon jellies. There in that dark water, lit from above, the translucent, floating orbs appear to glow from within. They undulate slowly and move even more so, bringing to mind a ghostly apparition. They are spellbinding.
In fact moon jellyfish are a pretty simple organism whose scientific name is Aurelia aurita. Most average about six inches across, although they can be as large as ten. They, like all other forms of medusae including the Portuguese man-of-war which we have discussed before, are not technically one living organism but a set of groups of cells that manage to work together. They have no respiratory, excretory or circulatory systems, although they are equipped with a neural net and gonads. There are, surprisingly, male and female moon jellies but only they know how to tell each other apart. It’s sort of mind boggling if you think about it too long.
These interesting critters are mostly found in tropical and subtropical waters with the Aurelia aurita being common to the Atlantic, Caribbean and Gulf of Mexico. There are other species of Aurelia – which are impossible to tell visually from the aurita type – that inhabit the Pacific and Indian Oceans. They consume a surprisingly varied diet of mollusks and other crustaceans, larvae, protozoa, fish eggs and even smaller medusae. The food is basically wrapped up in mucus and then directed via a tentacle to the gastro-cavity where it is dissolved by enzymes amoeba-style. Moon jellies can live over a year in good conditions. They live only about five to six months in the wild where, if they are not consumed by the many predators that find them tasty, they generally die from the effort of daily reproduction. That’s right; these guys reproduce themselves on a daily basis so after a few months they are so worn out that they are completely susceptible to infections and cellular degradation.
The thing that makes me particularly fond of moon jellies – aside from how darn cool they look – is their historical ties to seafaring in general and the old school buccaneers in particular. Moon jellies aren’t really capable of swimming per ce and have to rely on the tide to keep them moving. Because of this, and doubtless as a form of protection, they congregate together in groups that reflect moon and starlight at night. Frequent notations in logs and journals about great shoals of jellyfish glowing offshore are probably references to moon jellies. And they would have been a happy sight, not only as an extra source of light on a very dark sea but as an indication of something even more valuable: fresh food.
One of the moon jelly’s most common predators is the sea turtle, particularly the leatherback sea turtle that was a favorite delicacy of boucaniers and buccaneers. Considered healthier than pork, the turtles were savored boiled in stews, fried, roasted and smoked over a boucan to make a form of jerky. They were an all purpose food, and since they were large a few turtles could feed a whole ship’s crew. In the Great Age of Sail, turtles were caught whenever possible by both freebooters and navy ships as a welcome fresh meal. It may be as much an influence of seafarers as location that New Orleans in particular is fond of turtle soup to this day. More on ways to prepare turtle will be forthcoming on Friday.
Moon jellyfish are, thankfully, still relatively numerous all over the world. I’ve yet to see a large group at sea at night, but I hope to. Just another thing on the bucket list, but I’d count such an experience as a little gift from the gods of the sea. Until then, there’s always the museum.
Header: Moon jellies at the Anchorage Museum, Anchorage, Alaska
Remember that ‘50s monster movie Them that was all about the giant ants in the sewers? If you don’t, hit Netflix and check it out. Seeing it on TV when I was in elementary school scared the pee out of me because I hate, hate, hate ants. Period. Ask anyone. Did I mention I hate ants?
Well there’s an insidious creature out there in the sea that gives me the willies just about as much as ants: jelly fish. They’re pretty and all but when those tentacles touch your skin you wish you had never been born. Or I do anyway. Being mildly allergic my first jelly fish sting was kind of like being hit in the sternum by a lineman’s helmet just as someone set fire to my arm. Now I carry Benadryl and vinegar in my beach bag. So, of course, no stings since then.
All the same, while doing a little research for the second annual Horror on the High Seas Week I found out that pirates would sometimes use jelly fish as torture devices. The most popular one for the purpose of getting a captive to talk was the huge, ominous globe shown above: a Portuguese Man of War. Imagine my horror when I delved even more into these delightfully scary creatures and found out that just one was not an individual at all but a group of four polyps banded together to form a colony. A Portuguese Man of War is not an “it”, it’s a “them”. Oh yeah, and it’s also not a jelly fish.
The uppermost polyp is a gas-filled bladder called a pneumatophore which lets the creature(s) float and bob in the current and sometimes be pushed along by the breeze. This polyp gave the things their name; someone thought it looked like a warship in full sail. The next polyp is the tentacles. These have been recorded at up to 165 feet but most sources agree that 30 feet in length is about average. The tentacles have barbs, like a harpoon, and are covered with nematocysts filled with venom. When touching human flesh the burning pain can be intense and the injected toxin will scar the skin. Depending on the number of stings and a person’s sensitivity to the toxin, a Portuguese Man of War can potential kill a human being. Especially cheerful is the fact that dead creatures washed up on shore and even free-floating tentacles in the water can continue to inflict painful stings for hours. The other two polyps control digestion and reproduction.
Portuguese Man of War eat fish up to the size of a mackerel and they frequently have parasitic fish called Nomeus that live in their tentacles, even feeding off them, for their life cycle. Some scientists speculate that the Nomeus acts as a lure which attracts larger fish to its host but is immune to the neurotoxin. The Portuguese Man of War ranges the ocean and sea waters north and south of the equator, including the Gulf of Mexico, Caribbean, Mediterranean, Indian Ocean and South China Sea. Some of the largest specimens have been seen in and around Australia and they tend to range in packs of up to 1,000. Quite a sight, as long as you’re not in the water with them.
Because the Portuguese Man of War is so often mistakenly tagged a jelly fish, the usual cures for jelly fish stings are frequently applied to the skin when a Portuguese Man of War has been encountered. In fact vinegar, urine and other ammonia based cures only make the burning sensation more pronounced and increase the possibility of scarring. Cold water or, if at all possible, ice should be applied to the affected area and the skin left out in the air rather than bandaged. The worst of the burning will usually pass within an hour but trouble with breathing or continued or increased pain or redness at the site are a good sign that medical attention is needed.
And what of our pirate scooping a Portuguese Man of War out of the water with his cutlass and dangling it in front of his captive’s face to elicit the location of some treasure or other? Well, it wouldn’t be fair to spoil all the joys of Horror on the High Seas five weeks before we’ve even begun. Besides, I’m quite certain your imaginations can give you some inkling of what a clever pirate could do with “them”.Picture via National Geographic Animals
Last week my younger daughter’s birthday coincided with spring break so we all took a little time off and spent it having fun. One of our outings was to the Anchorage Museum to see the new Mammoths and Mastodons exhibit (find information here). While we were at the museum we had to pop in at the Imaginarium and that meant I could visit one of my favorite exhibits: the tank full of moon jellies. There in that dark water, lit from above, the translucent, floating orbs appear to glow from within. They undulate slowly and move even more so, bringing to mind a ghostly apparition. They are spellbinding.
