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derek a. zelmer zelmeda4 at WFU.EDU
Tue Apr 4 06:40:07 EST 1995


On 3 Apr 1995, Jeffrey Lotz wrote:

> In response to Zelmer
> 
> The term "endo-symbiotic" as a synonym of 
> "not-free-living" of course does not 
> include "ecto-symbionts". Therefore, if we 
> are to use some form of it the correct term 
> is "endo/ecto-symbiotic" a rather contrived 
> word. "Endo/ecto-symbiont" does not seem to 
> have many, if any advantages over the word 
> "parasite".

There are also ecto- and endo- parasites, the prefix is locational. The 
term symbiont encompasses both ecto and endosymbionts. It has the advantage
over the term "parasite" in that it implies "not-free-living" without
specifying an effect on the host...parasite defines the effect the symbiont
has, which is negative.
> 
> Whether the word "parasite" should be a 
> synonym of "pathogen" or "not-free-living" 
> or for that matter of something else is 
> only of moderate interest.

"Pathogen" specifies that an organism is disease-causing. It is a *subset*
of the term parasite. Morbidity is not always the end result of parasitism,
the net negative effect can usually be less severe.

> 
> Now, it may be appropriate to call the 
> things that parasitologists study 
> "endo/ecto symbionts" or for that matter 
> "rutabagas." However, regardless of what we 
> call them the things that parasitoligists 
> study are organisms that are 
> "not-free-living." That is the way that 
> most parasitologists use the term in their 
> work and it is this aspect of their nature 
> that holds the discipline of parasitology 
> together. It is what being parasitic is all 
> about.  

I think that if you did a survey you would find that most parasitologists
study symbionts that have a net negative effect on their hosts...the
net negative effect is the unifying theme. Parasitologists study parasites.
It is rather a circular argument to say that a parasite is what a 
parasitologist studies.

> However, "parasite" is more 
> often used in the sense of 
> "not-free-living" than it is as a synonym 
> of "pathogen", at least among those that 
> call themselves "parasitologists."

Not all "not-free-living" organisms are parasites, and not all parasites 
are pathogens. Some would say that not all pathogens are parasites, but 
I'm sure we would all agree that all parasites are "not-free-living". 
Hope this clears things up.

		Derek Zelmer, theoretical rutabegologist



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