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encysting cercariae

Wed Jul 16 09:12:49 EST 1997

I've become interested in trematode cercariae that encyst "on" 
something in the environment (reportedly, things like aquatic 
vegetation, etc.), e.g., paramphistomes, notocotylids, etc.  I was 
wondering whether anyone rountinely collects snails that are infected 
with cercariae of these types, and if so, if you'd be willing to 
share some; I'd like to get as many species as I can running in the 
lab.  If so, please contact me at my address below.  Of course, I 
could pay shipping, etc.  OR, if you have information, observations (or 
suggestions) you'd like to share, please feel free to throw those 

Overall, I'm interested in the cercarial behavior in the environment, 
e.g., substrate choice, settling behavior, energetics of the 
cercariae (in many the tail is dropped but it [the tail] continues to 
swim....lost energy?), etc.   One thing in which I'm curious is 
whether there are any parallels between these types of encysting 
cercariae and marine invertebrate larvae (and the factors that go 
into their settlement behavior).  

So, if you have comments on any of the above (or could share 
ideas/observations/snails), please let me know, OR post comments to 
the group.  My observation on all the "junk" posts to this group is 
that they seem so overwhelming because of the general lack of 
substantive discussion.  Perhaps if we get some involved discussion going 
again, the number of smut and parasite-panacea ads won't seem so 

For example, are folks comfortable with the idea that cercariae that 
encyst "on" something are in general ancestral to those that encyst 
"in" a next intermediate host?  Is there a nice, neat evolutionary 
trend from encysting on a plant to encysting on an animal to 
encysting 'in' an animal?  Any discussion (to the group or to me) is 

If you've read this far, sorry about the lengthy post!
Eric J. Wetzel, Ph.D.           phone: 765-361-6074
Department of Biology           fax:   765-361-6149      
Wabash College                  email: wetzele at wabash.edu
PO Box 352
Crawfordsville, IN 47933

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