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Brian E. Keas keasbe9 at WFU.EDU
Fri Feb 17 12:50:53 EST 1995

On 15 Feb 1995, derek a. zelmer wrote:

> Brian Keas stated the following requirement for an organism to be 
> considered parasitic:

> > 2. An organism (or life-cycle stage) that ABSOLUTLEY CAN ONLY use one host 
> > at a time to obtain host resources COULD be a parasite.  {An organism that 
> > could POSSIBLY obtain resources from two hosts simultaneously CANNOT be a 
> > parasite (a cow could possibly obtain resources from two separate plants 
> > (grasses) in the same mouthful; not a parsite).}
> Some people would argue that this is simply a matter of scale. If 
> parasites were larger, perhaps they could feed on two organisms at one 
> time, or perhaps cows are just large parasites.
> Just more fuel for the fire....Derek A. Zelmer
What I was trying to do in my definition of a parasite was have a 
definition that clearly and without exception included organisms that 
almost all people would agree to be parasites.  Clearly, cows don't fit 
most people's definition of a parasite and thus my definition was made to 
exclude cows and other 'classic' herbivores.  It is somewhat a matter of 
scale, but it would be very difficult to imagine an adult tapeworm, for 
example, infecting two (hosts) intestines simultaneously, regardless of 
its size.

Brian Keas
keasbe9 at wfu.edu
Wake Forest University
Winston-Salem, NC 27109

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