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Paratenic host?

Kimo Morris morrisk at bcc.orst.edu
Tue Nov 19 20:33:58 EST 1996

However, most of the
> definitive coral reef fish hosts that I have found, do not eat copepods, but do
> eat other and larger crustaceans as well as small fishes, which may be
> infected with camallanids.  Therefore, in order to reach potential definitive
> hosts, many camallanid nematodes may use paratenic hosts, in which no development
> will occur, as "trophic bridges" or "trophic channels" to move up the food web and
> reach other potential definitive hosts/
> -- Mark Rigby, University of Alberta, Edmonton AB, Canada T6G 2E9

Mark!  Great to see your name in this thread.  It's been a while, fellow 

Ahem... onto the issue at hand.  The idea of "trophic channels" yields 
interesting evolutionary implications for the parasite.  I was always 
taught that a paratenic host is not a "necessary" component of multihost 
life cycles, but now I see that this is not necessarily the case.  It 
may not be as accidental as I once thought.  Obviously, it is in a 
multihost parasite's best interest to evolve multiple methods of getting 
to the definitive host (e.g. larval tapeworm cysticercoid vertically 
transmitted to higher carnivorous fish without further development).  
After all, the challenge of being a larva is simply to make it to the 
definitive host - establishing other avenues to get to that final host 
is evolutionarily favorable.  If one were to model a multihost 
lifecycle, I'm sure that adding more paratenic hosts (i.e. increasing 
the potential reservoir for future parasites) would yield a stablizing 
trend.  COOL!  I'm gonna try that tomorrow!  I'll let you know what I 

-- Kimo

PS - Mark, I saw your epibiont beach hopper paper.  It proved useful for 
a mite paper on which I'm working.  Congrats.

* A. Kimo Morris             Office - (541)737-2453 *
* Department of Entomology      FAX - (541)737-3643 *
* Oregon State University    E-Mail -               *
* Cordley Hall 2046            morrisk at bcc.orst.edu *
* Corvallis,OR 97331-2907,USA                       *

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