Sarah:
 
The best molluscan camouflage I can think of comes from the nudibranchs.  The
Sargassum nudibranch (Scyllaea pelagica) looks almost identical to the sargassum
weed on which it lives.  Of course so does the Sargassum shrimp and Sargassum
fish, so maybe thats the way you survive in very clear water.
 
If memory serves, the nudibranchs may also provide an example of convergent
evolution.
Most shelled snails have twisted themselves so their anus is by their heads (a
process called torsion) and the rest of their bodies are tucked safely inside
their shell.  In most nudibranchs and nearly shell-less opisthobranchs, the snails
have untwisted (detorsion) themselves since if they are not going to carry a
shell, its probably unpleasant to defecate on one's head.  In a few nudibranch
spcies, though, instead of untwisting, they put in an extra twist (untorsion) to
get the anus away from the head.  This extra twisting is not visible externally,
but apparently you can see it if you dissect out the nudibranch's central nervous
system (we all do this in our spare time, right?).
 
Larry Eaton
North Carolina
 
Sarah Watson wrote:
 
> Dear all:
>    Just a random question, but do any members of Gastropoda (or any other
> mollusks for that matter) display either Mullerian or Batesian mimicry? I
> can't seem to think of any examples and it is driving me up the wall. Also are
> there any members of all classes of Mollusca that display Convergent
> evolution, Adaptive radiation, Co-evolution, or Character displacement?  I
> can't seem to think of mollusks but I sure can think of insects
> Thanks
> Sarah Watson