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filthy
SFN Die Hard
USA
14408 Posts |
 Posted - 11/27/2007 : 07:13:48
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All things dull and ugly,
All creatures short and squat,
All things rude and nasty,
The Lord God made the lot.
Each little snake that poisons,
Each little wasp that stings,
He made their brutish venom,
He made their horrid wings.
All things sick and cancerous,
All evil great and small,
All things foul and dangerous,
The Lord God made them all.
Each nasty little hornet,
Each beastly little squid,
Who made the spiky urchin,
Who made the sharks, He did.
All things scabbed and ulcerous,
All pox both great and small,
Putrid, foul and gangrenous,
The Lord God made them all.
~~ Monte Python
Of all the evolutionary stories, the saga of the parasites is arguably the one of the strangest. These are organisms that depend to greater or lesser extent upon the nutrients and protection of other, unrelated species.
First a bit of nomenclature; what might be a parasite? Is, say, a vampire bat a parasite? Yes, at least by loose definition. One species, of three, feeds solely upon blood. It attacks other animals and when it's eaten it's fill, it abandons it's prey. Female mosquitoes too, rely upon a blood meal to develop their eggs, although the males are nectar-feeders, and these might be considered as pretty much the same. So the dividing line between predator and parasite can be a tad fuzzy in spots. Arthropods such as ticks, fleas and lice are certainly parasites and they will stay on a host for life, or in the case of hard ticks, until the female is ready to lay eggs. Then she must drop off to lay them and dies soon after. Beyond occasionally passing along some pretty nasty microbes, themselves parasitic, these and other tiny exoparasites are pretty innocuous. It is the endoparasites that can, and often do, wreak havoc upon any host they infect -- and at this point, those of tender sensibilities and loose gag reflexes might be well advised to abandon this writing.
If I have a favorite endoparasite, it is the Guinea Worm, Dracunculus medinensis. I like them particularly well because I've never had one and, with any luck at all, am unlikely ever to make close acquaintance with any.
I also like them because their life cycle is fairly typical of many endoparasites; complicated and more than a little astonishing.
The larval worm, a minute creature, first inhabits a tiny copepod called a water flea. It passes to it‘s ultimate host when that unfortunate drinks some water infested with the fleas. The fleas are digested and the worm larvae, unscathed, settle into the small intestine. From there, they move into more spacious and comfortable quarters in the body cavity, where they feed and grow to maturity. At somewhere around a year old, give or take, the adult worms breed. The males die and are absorbed and the females, who are now somewhere in the appalling neighborhood of three feet long and look like a strand of over-cooked spaghetti, then begin their journeys into the lower extremities. Once there, they create large blisters and emerge through them, and at this point, their host is experiencing an excruciating pain that feels like his lower leg is actually burning (the Crusaders called the Guinea Worm, “the Fiery Serpent“). This encourages putting the limb in water to sooth it, at which point the worm releases her thousands of eggs and thus is the cycle completed.
I like the Guinea Worm because it so nicely demonstrates the draconian control many endoparasites exert over their hosts. There are others that exert even more, some few of which we s
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"What luck for rulers that men do not think." -- Adolf Hitler (1889 - 1945)
"If only we could impeach on the basis of criminal stupidity, 90% of the Rethuglicans and half of the Democrats would be thrown out of office." ~~ P.Z. Myres
"The default position of human nature is to punch the other guy in the face and take his stuff." ~~ Dude
Brother Boot Knife of Warm Humanitarianism,
and Crypto-Communist! 
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Edited by - filthy on 11/27/2007 08:17:17
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pleco
SFN Addict
USA
2998 Posts |
Posted - 11/27/2007 : 07:19:26 [Permalink]
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Well, it's all Eve's fault, you know.
Great post, better than coffee in the morning!  |
by Filthy
The neo-con methane machine will soon be running at full fart. |
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Kil
Evil Skeptic
USA
13477 Posts |
Posted - 11/27/2007 : 08:43:36 [Permalink]
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| Great work again Filthy! Looks like another SFN article to me... |
Uncertainty may make you uncomfortable. Certainty makes you ridiculous.
Why not question something for a change?
Genetic Literacy Project |
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Dr. Mabuse
Septic Fiend
Sweden
9688 Posts |
Posted - 11/27/2007 : 13:11:31 [Permalink]
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The last picture in Filthy's extraordinary essay cannot be viewed simply in Internet Explorer (and possibly other browsers as well).
It's the server where the picture is stored that doesn't like people leeching from it.
To view the image:
1) Copy this URL: http://tolweb.org/tree/ToLimages/Melanocetus_pair%2e500a.jpg
2) Open a new browser, and paste the link. |
Dr. Mabuse - "When the going gets tough, the tough get Duct-tape..."
Dr. Mabuse whisper.mp3
"Equivocation is not just a job, for a creationist it's a way of life..." Dr. Mabuse
Support American Troops in Iraq:
Send them unarmed civilians for target practice..
Collateralmurder. |
| Edited by - Dr. Mabuse on 11/27/2007 13:21:32 |
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filthy
SFN Die Hard
USA
14408 Posts |
 Posted - 11/27/2007 : 16:31:38 [Permalink]
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Thanks for the kind words, guys; they are appreciated.
Doc, I dunno what's happening with that image; it's worked just fine for me. If necessary, I'll hunt up another.
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"What luck for rulers that men do not think." -- Adolf Hitler (1889 - 1945)
"If only we could impeach on the basis of criminal stupidity, 90% of the Rethuglicans and half of the Democrats would be thrown out of office." ~~ P.Z. Myres
"The default position of human nature is to punch the other guy in the face and take his stuff." ~~ Dude
Brother Boot Knife of Warm Humanitarianism,
and Crypto-Communist!
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marfknox
SFN Die Hard
USA
3739 Posts |
Posted - 11/28/2007 : 10:09:35 [Permalink]
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Man! I just ate lunch!  |
"Too much certainty and clarity could lead to cruel intolerance" -Karen Armstrong
Check out my art store: http://www.marfknox.etsy.com
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| Edited by - marfknox on 11/28/2007 10:10:17 |
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filthy
SFN Die Hard
USA
14408 Posts |
 Posted - 11/28/2007 : 13:04:40 [Permalink]
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Originally posted by marfknox
Man! I just ate lunch!
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My work here is done.... I further advise never to have lunch with the zookeepers. 
Aside from a bit of a gross-out, I hope you enjoyed it. The study of parasitology is one of the most fascinating.
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"What luck for rulers that men do not think." -- Adolf Hitler (1889 - 1945)
"If only we could impeach on the basis of criminal stupidity, 90% of the Rethuglicans and half of the Democrats would be thrown out of office." ~~ P.Z. Myres
"The default position of human nature is to punch the other guy in the face and take his stuff." ~~ Dude
Brother Boot Knife of Warm Humanitarianism,
and Crypto-Communist!
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filthy
SFN Die Hard
USA
14408 Posts |
 Posted - 11/29/2007 : 03:47:04 [Permalink]
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So.... No one has an answer to the quiz. I don't understand; it's only a single question and rather a simple one at that. | And now, here is your quiz question: Is the male of M. johnsonii a parasite or a symbiote? Or both.... Or neither…. |
I'll admit that multiple choice answers can be confusing, but, c'mon, really, these are very straightforward. Are no one's thought process' in working order?
I have implied that Denyse O'Leary is an "ambulatory intellectual hiatus" -- should I have kept my implications closer to home?
You all flunk!
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"What luck for rulers that men do not think." -- Adolf Hitler (1889 - 1945)
"If only we could impeach on the basis of criminal stupidity, 90% of the Rethuglicans and half of the Democrats would be thrown out of office." ~~ P.Z. Myres
"The default position of human nature is to punch the other guy in the face and take his stuff." ~~ Dude
Brother Boot Knife of Warm Humanitarianism,
and Crypto-Communist!
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The Eaters of the Living
