For the first time since I started writing this column in December 2013, I will introduce a local land snail as our “Shell of the Week”. Sanibel and Captiva islands are homes to rich assemblages of pulmonate (air-breathing) gastropods (snails). One of the most ubiquitous is the Florida Flatcoil, Polygyra septemvolva Say, 1818, as species that may reach about ½-inch, but that locally may be found in the 3/8-inch diameter range. As the vernacular name implies, the Florida Flatcoil has a flat, discoidal shell with a large number of tightly coiled whorls (pretty much like a garden hose coiled around itself). The shell opening has a characteristic tooth-like expansion. Shells of the Florida Flatcoil may be found along the edges of dried water puddles, where they accumulate during rainstorms.
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The Florida Flatcoil, Polygyra septemvolva. Photos by José H. Leal.