Mollusks

The Florida Prickly Cockle

The Florida Prickly Cockle, Trachycardium egmontianum (Shuttleworth, 1856), is one of the most commonly found bivalves along the shores of Southwest Florida. Its common name originates from the spiny projections distributed along radial (oriented from the “beak” to the edge) ribs. As other species of cockles do, Florida Prickly Cockles use their foot as a “pole vault” or lever to propel themselves away from threatening predators such as Apple and Lace Murexes. Almost pure white shells, known as

The Lettered Olive

The Lettered Olive, Oliva sayana Ravenel, 1834, is a relatively common species on the beaches and sand flats of Southwest Florida. Despite its relative abundance, it is a desirable, collectible species, certainly because of its glossy, colorful shell, and its assorted variations. The locally famous Golden Olive is nothing but a varietal of the species in which the shell lacks darker pigments. Lettered Olives feed on marine worms, crustaceans, small bivalves, among other prey items. They are fast

The Stiff Pen Shell and its Nacre

The nacreous shell layer of Pen Shells imparts the trademark, dark iridescence that is so typical to the inner surface of Pen and other shells. The nacreous layer, or mother-of-pearl, is composed of thousands of very thin, flat, colorless, translucent calcium carbonate crystals (also known as tablets). These flat crystals cause incident light to scatter and reflect back at different angles, which is perceived as distinctive colors. The tablets are separated thin layers of organic “adhesive,” and

The One-tooth Simnia

One-tooth Simnias, Simnialena uniplicata (G. B. Sowerby II, 1849), are elongated marine gastropods that may reach 20 mm (about 4/5 inch). They live exclusively on the “branches” of Sea Whips, which are colonial organisms related to corals. One-tooth Simnias feed on the mucus of and materials entrapped by Sea Whips, apparently without damaging the Sea-whip polyps. They spend most of their lives on the hosts (except for the time they spend in the plankton as larvae), and may be yellow, white, red

The Florida Fighting Conch

The Florida Fighting Conch, Strombus alatus Gmelin, 1791, is one of Southwest Florida’s best known and most abundant mollusks. So much could be said about that species, but today I want to focus on some differences between the juvenile (young) and the adult shells. In many species of the conch genus Strombus, the juvenile (young) shell differs considerably from that of the adult. The texture of the adult shell is usually smooth, and its color is very variable: there are different hues of orange,

The Atlantic Pearl Oyster

Although other mollusks are capable of producing pearls, the emblematic bivalve making true, valuable, old-fashioned pearls is the Silver-lip Pearl Oyster, Pinctada maxima (Jameson, 1901), which may reach about 12 inches in size. That species is not native to the Atlantic Ocean, and its closest relative in our area is the much smaller Atlantic Pearl Oyster, Pinctada imbricata (Röding, 1798), at about 3 inches. The pictures show the shell and a live individual of the Atlantic Pearl Oyster. The sh

The Mangrove Periwinkle

The Mangrove Periwinkle, Littoraria angulifera (Lamarck, 1822), is an inch-long marine gastropod that inhabits the fringes of mangrove forests of the western Atlantic Ocean, including the barrier islands of Southwest Florida. Unlike its close relative, the Cloudy Periwinkle, which forms aggregations on dead tree trunks and other dead wood, the Mangrove Periwinkle prefers to live on live mangrove trees, in particular on the prop roots, trunk, and branches of Red Mangrove trees, as seen in the pho

The Atlantic Fig Snail

The Atlantic Fig Snail, Ficus papyratia (Say, 1822), belongs in the category of the desirable local shells. Its shell is thin, and shaped like a fig (or a pear). The shell opening, or aperture, tapers gently toward the extremity of the anterior canal. The shell color is pinkish-gray to light-tan. The animal is cream-colored with dark and whitish spots. The Fig Snail’s egg cases are stacked on top of one another and attached at one small area of the fluted edge. The Atlantic Fig Snail. The egg ca

The Striate Bubble

The Striate Bubble, Bulla occidentalis A. Adams, 1850, is a local gastropod that may be seen alive in large numbers during the winter at the east end of Sanibel and other protected areas. Its fragile, barrel-shaped shell may reach 25 mm (one inch). The snail, when active, completely envelops the shell, but may retract completely into it when threatened. The Striate Bubble is a burrower, living in sandy-mud areas. Bubble snails and their relatives are hermaphroditic animals, having functional mal

The Wedge Piddock

The Wedge Piddock, Martesia cuneiformis (Say, 1822), is a wood borer that may be found in driftwood and floating logs in the Western Atlantic Ocean and Gulf of Mexico. The shell, which may attain ¾ inch in length, is usually pear-shaped, and very thin. Typically, Piddock clams have the anterior (wider) part of the shell equipped with rows of tiny tooth-like projections. These act as a cheese grater, enabling the clam to bore its way into the wood. For readers who collect this column: a closely r