Cercariae emergence from snails?

Brian E. Keas keasbe9 at WFU.EDU
Wed Apr 26 13:22:10 EST 1995


Does anyone out there know of any recent work (last 10-20 years) describing 
the methods that various cercariae use to get out of the snail 
intermediate host?  The only references I could find are the 3 cited by 
Wright in "Flukes and Snails" (1971) dating 30+ years ago describing
migrations within the different sinuses until penetrating through the 
mantle.  This makes sense for the motile cercariae even though the actual 
mechanism of penetration was not given.  Schmidt and Roberts list a 
reference to escape glands in schistosome cercariae but also say that 
"their function is unknown."  Do other cercariae have similar glands?  
Also, what about non-motile cercariae (at least when outside of the 
snail)?  It is hard for me to imagine them maneuvering about inside the 
snail and then penetrating the skin.
    I understand that many rediae have birth pores, but that 
some do not.  How do the cercariae even get out of the rediae then?   
 
I realize that I packed a lot of questions in this post, but I would be 
grateful for any bits of information regarding any of them.

Thanks,

Brian Keas   ->    keasbe9 at wfu.edu


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