what is the origin of parasites?
548421
Parasites are creatures that originally could not absorb the nutrients they needed from their natural environment, so they adapted to be able to forcibly extract them from higher animals. It also refers to creatures whose metabolism requires their gestation to take place in a warm space with ample food (i.e. the inside of another animal)
129650
There are hundreds if not thousands of different Nematoda. by nature they are parasites but many are beneficial to humans.  The correct balance of Nematodas and incects is crutial to the environmnet as the Nematodas keep the incect population from taking over the world uncheked.
401609
tapeworm's don't have eggs. you know how they have all those little segments? when its time to "procreate" they just drop one of those segments. it works through the intestines and comes out through your solid waste then (hopefully) gets picked up again to be consumed in another form thereby infecting another living creature with a tapeworm. \nnow aren't you happy you asked that question?
522420
In biology, a host is an organism that harbors a virus, parasite, mutual partner, or commensal partner, typically providing nourishment and shelter.\n\nExamples: A cell can be host to a virus, a legume plant can be host to helpful nitrogen-fixing bacteria, an animal can be host to a parasitic worm, e.g. a nematode. \nA primary host or definitive host is a host in which the parasite grows mature; a secondary host or intermediate host is a host that harbors the parasite only for a short transition period. For trypanosomes, the cause of sleeping sickness, humans are the primary host, while the tsetse fly is the secondary host.\n\nThe host range or host specificity of a parasite is the collection of hosts that an organism can utilize as a partner. In the case of human parasites, the host range influences the epidemiology of the parasitism or disease. For instance, the production of antigenic shifts in Influenza A virus can result from pigs being infected with the virus from several different hosts (such as human and bird). This co-infection provides an opportunity for mixing of the viral genes between existing strains, thereby producing a new viral strain. An influenza vaccine produced against an existing viral strain might not be effective against this new strain, which then requires a new influenza vaccine to be prepared for the protection of the human population.\n\nThere are also reservoir hosts. These are vertebrates that host an infection while it isn't infecting humans and is used by the disease as a source of maintenance. a single reservoir host maybe be reinfected several times.\n\nIn parasitology, an intermediate host is an organism within which a parasite does not sexually reproduce. It may grow or reproduce asexually, but there is no exchange of genetic material between individuals. The host in which the parasite reproduces sexually is referred to as the definitive host. For example, the broad fish tapeworm Diphylobothrium latum develops in fish for part of its life cycle but only reproduces sexually when it is in a mammal digestive tract, so its intermediate host is the fish and its definitive host is the mammal.\n\nBecause the life cycles of many parasites are poorly understood, sometimes the "more important" organism is arbitrarily defined as definitive, and this designation may continue even after it is determined to be incorrect. For example, sludge worms are sometimes considered "intermediate hosts" for whirling disease, even though it is known that the parasite causing the disease reproduces sexually inside them
1133326
The hen, or the ancestors of the hen, had to come first. The mode of reproduction would have evolved later when the original mode of reproduction became dangerous to the parent's health, or just more convenient.\n(please don't flame me for this; most of the Theory of Evolution is proven to be true in that humans are taller than they were a hundred years ago, immune systems learn to fight off diseases, many different species have split from one, etc.)
939154
There is a madsci article about this question at: http://www.madsci.org/posts/archives/feb98/888691550.Ph.r.html\n\nHope that helps...the site discusses the hypothesized origins...
279116
Several billion years ago, the first simple amino acids formed crude proteins and RNA to act as simple genetic coding. Over time, these nondescript organisms evolved into bacteria, then photosynthesizing bacteria. Eventually they evolved into simple invertebrates capable of sexual reproduction, and through tweaking of the ovulatory cycle, were able to lay fertilized eggs outside of their body. These invertebrates became fish, then amphibians, then reptiles, then birds. From those birds evolved the ancestor of the chicken which after 4 billion years of evolution was already capable of laying eggs.\n\nThe end.
43739
In evolutionary terms, a chicken was first hatched from an egg of a slightly different animal.  Therefore, the egg came first.
460581
it started with chemicals ,followed by ,very simple unicellular things,they worked there way up to amoebas,and it was only a couple of million years to get to bacteria and stuf like coral after that ,then it becomes complicated,\n\nhumans came from out of space i think,they were put here and primitive beings that were already here were maybe genetically improved by those who came from the stars.\n\nas to how humans come ,that is another question
476515
Most would say the chicken, which is NOT true;\n\n"The egg! The amniotic egg (though not a chicken egg) was around on earth thousands of years before the chicken ever evolved."\n\nEggs existed long before chickens, according to On Food and Cooking: The Science and Lore of the Kitchen by Harold McGee. These all-in-one reproductive cells, incorporating the nutrients to support life, evolved about a billion years ago. The first eggs were hatched in the ocean. As animal life emerged from the water about 250 million years ago, they began producing an egg with a tough leathery skin to prevent dehydration of its contents on dry land. The chicken evolved only about 5,000 years ago from an Asian bird.\n\nWhat makes a chicken "more evolved" than a fly?  Is it because a chicken is bigger than a fly?  Both flies and chickens have had the same amount of time to evolve to their present state.  The ancestors of chickens and flies split\noff from their common ancestor a long time ago, but both have continued to evolve since then.
1003854
Yeah there is a lot of debate on where it originally came from. This is all I could really find:\nhttp://en.wikipedia.org/wiki/Aids#Origin_of_HIV\n\n(I can't believe that person copy and pasted the whole article from Wikipedia!! lol)
481658
As a starting point: http://images.search.yahoo.com/search/images?p=human+parasite&tab=Images&ei=utf-8&fr=my-vert-img-top\n\n(WARNING: Some of those pictures are graphic)\n\nYou can also enter the particular parasite name your are interested in to see more specific pictures.
551406
Which parasite?\nBacterial, viral, protozoa etc = no\nLeech, insect, helminth etc = sort of \nCuckoo, vampire bat etc = yes\n\nI think there are parasites in every phyla.
1074437
I found this article on parasites and fish.  Hope it helps.\n\nhttp://www.charkbait.com/article/RAPC2.htm
86425
The first chicken was hatched from an egg of something that was not quite a chicken. That's evolution :-)
455221
Intestinal parasites. Also lots of different diseases could be responsible. See a doctor!
627308
maybe the origin of species has something