Excerpts from Jim Conrad's
from the July 10, 2005 Newsletter issued from the Sierra Nevada foothills
somewhat east of Placerville, California, USA
SMALL WATER SNAIL
This week I strapped on my backpack and headed into the mountains with my radar set for aquatic plants and animals. My first stop was the bullfrog pond I've spoken of. I lay in the grass at the pond's edge with my nose right up to the water, my handlens actually touching it, for I wanted to see things closely. This fair-sized pond is bordered by cattails and its surface is about 4/5ths overgrown with water milfoil so all that shade keeps down the algae. You can see several feet into the water, and your view ends not because of muddiness but because of watery shadows.
What caught my attention wasn't something poking its nose from deep shadows, however, but rather a slow-moving glisten ascending the side of a dislodged smartweed root floating at the water's surface.
The glisten-maker was an aquatic snail, brown, about ¼-inch long, and its transparent shell was so unusual that I thought I might be able to identify it. Instead of the shell gradually spiraling to its tip, the first loop accounted for about 5/6ths of the shell's length, with the remaining loops relegated to the tip. Sure enough, my books provided a picture of this one, not only because of its unusual shell but also because the species is so common. The name in my book was Small Water Snail, though another name for it on the Internet is Pewter Physa. It's PHYSA HETEROSTROPHA and you can see it at http://www.jaxshells.org/0328az.htm
Since the shell was transparent silvery air pockets and assorted blobs that might pass for organs were clearly visible. When the snail reached the water's surface it turned sideways and as it continued grazing the root's slimy surface two long antennae atop its head gracefully groped before it and two slender-stalked eyes below the antennae ogled the surface rolling beneath them. Then from beneath the shell's upper rim emerged a fleshy, earlike fold of elastic flesh that rolled itself into a coil.
The coil opened at the water's surface, and this was the reason the little snail had come to the water's surface -- to send up its snorkel for air. I saw a another silvery bubble form within its shell, then the snorkel was retracted and the snail turned back into deeper water. The whole operation went so smoothly, with the snail never pausing or changing its demeanor at all, that I felt like applauding its adroitness and savoir-faire. This was one cool little snail, and I was glad to have made its acquaintance.