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Southwest Florida Shells with Emphasis on Sanibel & Captiva

By José H. Leal

Family Muricidae

Stramonita floridana

(Conrad, 1837)

Florida Rock Snail

Shell size to 75 mm; shell solid, elongate. Shell sculpture of fine spiral lines with weak axial growth lines. Last whorls sometimes with nodules on shoulder. Color variable, light gray, yellowish, or tan, usually mottled or checkered with darker brown, grayish, or orange marks. The column-shaped egg cases reach only about 6 mm height, and internally pigmented with burgundy or purple, thanks to the presence of a substance called murexin. The supplementary photo shows a cluster of egg cases found by Wendy Ottati on Sanibel, in June 2017. The number and density of cases suggest that females in this species are capable of communal spawning, i.e., several females will lay egg cases simultaneously, on the same spot. Photo of egg cases by Pam Rambo.