Mollusks

The Common Egg Cockle

The Common Egg Cockle, Laevicardium serratum (Linnaeus, 1758), belongs to the Cockle family Cardiidae, a group of bivalves represented locally by at least nine species, including the Florida Prickly Cockle and the Atlantic Giant Cockle. Egg Cockles are so called because of their smooth, egg shell-like shells. Fully grown Common Egg Cockles typically measure a little less than two inches, and the scientific name of the species alludes to the finely serrated internal surface of the shell edges. An

The Squared Turrid

The Squared Turrid, Glyphoturris quadrata (Reeve, 1845), belongs to a relatively obscure family of marine gastropods, the Mangeliidae. Little is known about the Squared Turrid biology and feeding habits, but shells or the species are not uncommon along the shores of our barrier islands. Fully grown shells typically measure about 8 mm (1/3 inch). The two shells in the photos represent, on the left, a fully mature individual, and, on the right, an immature one. The main difference, other than the

The Zigzag Scallop

The Zigzag Scallop, Euvola ziczac (Linnaeus, 1758), lives offshore along the coast of Southwest Florida and other parts of the tropical and subtropical western Atlantic. Its shell is circular, and the two half-shells, or valves, are strongly dissimilar, with the lower valve strongly concave, and the upper valve flatter, slightly convex. The valves are also remarkably different in color; with the top, flat valve being colorful, usually displaying a pattern of brown or reddish-brown radial bands a

The Beau’s Vitrinella

Beau's Vitrinella, Cyclostremiscus beauii (P. Fisher, 1857), at about 12 mm in diameter (about 0.5 inch), is most likely the largest local member of the micro-gastropod family Tornidae, commonly known as Vitrinellas. Small sizes, sometimes never reaching beyond 1/8 inch, and strong similarity among species render Vitrinellas difficult to study, but the "larger" size, characteristically "keeled" shell outline, and typical spiral cords make Beau's Vitrinella relatively easy to identify. This speci

The File Fleshy Limpet

The File Fleshy Limpet, Lucapinella limatula (Reeve, 1850), is one of the three species of Keyhole Limpets (family Fissurellidae) that may be found along the barrier island of Southwest Florida. It has a relatively small shell (about 10 mm, or a little less than an inch), with a relatively large "keyhole" orifice. As in other Keyhole Limpets, the orifice helps direct waste water away from the snail's head and gills. File Fleshy Limpets have "rays" of colors ranging from red to brown set against

The Delicate Ark

The Delicate Ark, Fugleria tenera (C.B. Adams, 1845), is an uncommon western Atlantic member of the Arcidae, a family of marine bivalves that also includes the Turkey Wing and the Transverse Ark, among others. The delicate Ark may reach slightly more than one inch (25 mm) in size. It differs from others, related species by its thin shell, with an alternating pattern of thicker and thinner radial ribs, which are in turn crossed by concentric ridges. Living delicate Arks have a hairy, rich periost

The Meta Keyhole Limpet

The Meta Keyhole Limpet, Diodora meta (Ihering, 1927), is a locally rare and elusive gastropod, also found in other parts of the Gulf of Mexico and of the western Atlantic Ocean. Its shell measures about 12 mm (0.5 inch), and has a roundish “keyhole” orifice that distinguishes the species from others in the area. Keyhole Limpets cling to hard surfaces; the orifice helps redirect water containing body wastes away from the head and gills of the animal. The Shell Museum collection has only two shel

The Atlantic Necklace Turrid

The Atlantic Necklace Turrid, Pilsbryspira monilis (Bartsch & Rehder, 1939), is a predatory gastropod, moderately uncommon on Sanibel and Captiva islands. The species reaches about 15 mm (0.6 inch); the shell is slender, brown, with small white beads forming a spiral “necklace-like” pattern (hence the scientific name of the species, monilis, meaning necklace, or string of beads, in Latin.) The Atlantic Necklace Turrid shell aperture (opening) forms an indentation at its posterior end (photo on

The Giant Tun

The Giant Tun, Tonna galea (Linnaeus, 1758) is a large gastropod, with a shell that may reach in excess of 150 mm (6 inches). The shell globose, with a short spire, and ornamented with around 20 spiral, strong but flat ridges. A thin shell allows ridges to show on its internal surface. The Giant Tun has a broad distribution in tropical and subtropical areas of the world’s ocean. The species includes a long-lasting, free-living (planktonic) larval stage that allows dispersal via currents over lar

The Dall Wentletrap

Dall Wentletrap, Cirsotrema dalli Rehder, 1945, can reach more than 30 mm (about 1.2 inches). It has a chalky shell surface with ribs and a background pattern of spiral cords. In addition, about 2-3 thicker ribs per whorl are present in this species. Species in this genus display an outer shell layer called intritacalx, which easily wears off in older shells. Dall Wentletrap is more commonly found in deeper water. The shell on the left, measuring a little more than an inch, was collected in 201