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.
The Florida Flatcoil, Polygyra septemvolva. Photos by José H. Leal.