Southwest Florida Shells
by José H. Leal
Family Gastrochaenidae
Gastrochaena difficilis
(Deshayes, 1855)
Winged Chimney Clam
Shell size to 15 mm; shell thin, oval, inflated. Posterior extremity rounded. Antero-dorsal extremity widely open, gaping, higher than in Rocellaria stimpsoni. Umbo in anterior position, but not as anterior as in R. stimpsoni. Sculpture of commarginal cords. Most anterior part of valve represented by a wing-like projection of its ventral margin. Color translucent cream- to yellowish-white. The Winged Chimney Clam is a boring clam that spends its life lodged into the structure of empty shells or corals. The elegant shell of this species is very fragile and will not be found outside of its host structure. A young Winged Chimney Clam will settle onto a shell (or coral) and begin the boring process right away. Boring is done chemically, not mechanically. As its close relative, the Stimpson Chimney Clam, does, when its size eventually surpasses the thickness of the host shell, completely piercing it from side to side, the Winged Chimney Clam is capable of building a "dwelling" of mucus and sand and broken shell particles for its protection. The shell (paired valves) illustrated was collected by Dr. Jim Scatterday inside the hard colony of a moss animal (Bryozoa), on Gulfside City Park, on Sanibel.