Image of: Physella gyrina (tadpole physa)
ADW: 059.rjb1.jpg
Caption
Physella gyrina
. The light band (varix) on the shell shown here was caused by the snail's much slower growth during the winter. While the shell growth was slower at the varix, a thicker shell was produced at this site (which masks the dark mantle [skin covering the viscera] of the snail's body, that elsewhere shows through the translucent shell).
Contributors
Dr. John B. Burch, Ph.D.
(photographer, copyright holder), Mollusk Division, Museum of Zoology, University of Michigan
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