> A post about Physa.
>
> Aydin
> snailstales.blogspot.com
>

I tried replying on the site but the form kept clearing and asking if
I wanted non-secure content displayed.

Ctenidia are the primitive condition in gastropods.  Most of the
heterobranchs, including standard sea slugs and pulmonates, have lost
the ancestral ctenidia.  Many have evolved some substitute, e.g. the
lungs of pulmonates or the secondary gills of nudibranchs.

The freshwater pulmonates in my aquarium don't seem too picky about
animal or vegetable origin as long as it's slow enough to bite.  They
don't seem to like the filamentous green alga, though.

--
Dr. David Campbell
425 Scientific Collections
University of Alabama
"I think of my happy condition, surrounded by acres of clams"

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