definition

derek a. zelmer zelmeda4 at WFU.EDU
Thu Feb 16 10:56:47 EST 1995


On 15 Feb 1995, Steve G. Kayes wrote:

> 	Anyway, I believe that any movement of energy as it pertains to 
> the three laws of thermodynamics that is influenced in one organism by 
> another (read that diverted from one to another) is a parasite.  The 
> question raised by Mr. Faulkner about commensalism and its practioners is 
> only a matter of degree.  We say that the equation in this case is that 
> commensals do not have a net negative effect on the energy economy of the 
> host (the example of organisms in the termite intestine).  What we really 
> mean is that the typical host parasite system is not deleterious but this 
> begs the question because the host still expends its energy carrying 
> around the commensal population.  Even if the host derives the use of 
> cellulose breakdown products the host expended its ATP currency to do so.

I personally feel that a nutritional dependence on a host is an important 
character for defining a parasite. Including the energy loss caused by 
phoresis creates more confusion...for example, is the spanish moss 
parasitic on the plants it uses or is it merely a competitor? Are 
angiosperms parasites of their pollenators? At a quantam level everything 
affects everything else and there are no definitions, but I believe that 
our definitions should be based on a level that has measurable biological 
significance...in other words they should be limited by what we can test 
and observe. - Derek A. Zelmer



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