Mollusks

Shell of the Week: The Florida Slender Chiton

Chitons are mollusks with eight (sometimes seven) shelly plates called valves. The Florida Slender Chiton, Stenoplax floridana Pilsbry, 1892 reaches about 38 mm (1.5 inches) and is about three times as long as it is wide. The central areas of valves bear strongly beaded longitudinal ribs, and the end valves have concentrically arranged beads. Its color can be whitish to whitish-green, with markings of darker green or gray This species is not uncommon in the coral reef habitats of South Florida a

Shell of the Week: The Digitate Thorny Oyster

Reaching about 70 mm in size, Spondylus tenuis Schreibers, 1793, is one of the few species of thorny oysters (family Spondylidae) found in the western Atlantic. Its shell comes in varied colors, including rusty brown, brick red, orange, cream-yellow, whitish, or variations of these hues. The sculpture consists of flat or pointy spines that are longer toward the edge of the shell. The lower valve is almost always cemented to a hard surface, such as rocks, ship wrecks, or oil platforms, but someti

Meet the Comb Bittersweet!

Tucetona pectinata (Gmelin, 1791) is the most common out of two locally found species of the bittersweet family, the Glycymerididae. Its shell may reach 30 mm (about 1.2 inches), and is circular, with a sculpture of 20–35 relatively wide ribs that are flat in cross-section. As the image above shows, the ribs are overlaid with a microscopic sculpture of regularly spaced, commarginal (“concentric”) threads. The shell hinge (below) has about 20–24 small “teeth” that ensure that the shell valves clo

Shell of the Week: The Dubious Cerith

At about 4.5 mm (about 0.5 inch) in height, the Dubious Cerith, Finella dubia (d’Orbigny, 1840) is one of the small gastropod species that dwell in sea grass beds around Southwest Florida and other parts of the tropical Western Atlantic. Dubious Ceriths feed on plant and algal detritus. The shell is elongate, turret-shaped, with three or more strong spiral cords. The shell color may be cream-white to light-brown with faint spots of darker color. #finelladubia #dubiouscerih #scaliolidae #sanibeli

Shell of the Week: The Caribbean Melampus

Melampus monile (Bruguière, 1789) reaches about 16 mm in length. The shell is bullet-shaped, widest at posterior (upper) third. The spire is low. The aperture spans about ¾ of the shell length. The columella has two folds, one larger. The outer lip is smooth, but the internal surface of the aperture has about 12 raised, narrow spiral ridges. The color ranges from mahogany-brown to yellowish, with one broad, whitish spiral band below the suture of the last whorl. The shell interior is whitish. Th

Meal Time!

During field work in Fort Myers a few weeks ago, National Shell Museum Marine Biologist Jorden Falker captured this remarkable image of a Lightning Whelk (Sinistrofulgur sinistrum) holding a Sunray Venus clam (Macrocallista nimbosa) in preparation for a meal. Lightning Whelks are known to use the edge of their aperture (the external lip) as a “clam knife” to pry open bivalves. To that end, they have to place the clam just so, which they do using their big foot to adjust the clam’s position. Ligh

Shell of the Week: The Dimpled Wentletrap

Opalia morchiana (Dall, 1889) reaches about 12 mm in length. The species has a tall shell profile, with a variable number of wider axial ribs on each whorl and a large number of very small spiral cords crossed by finer axial ridges, which impart a pitted or dimpled aspect to the entire shell surface. The aperture is oval, uninterrupted, with a thick apertural lip. Former shell growth stops are indicated by a succession of irregularly spaced varices. Opalia morchiana is found between the depths o

Shell of the Week: The Dwarf Gaza

Microgaza rotella (Dall, 1881) reaches about 8 mm in length. The species has a depressed (low-profile) shell, which is unusual for a member of the family Solariellidae. The spire is low, and the only sculptural feature present other than growth lines is a series of short raised ridge-like bumps just below the suture (the line between two whorls.) The base has strong axial raised ridges that are stronger toward the deep umbilicus. The shell has a cream color with faint salmon-orange, irregular ba

That Snail is Back in Florida

The Giant African Snail, Lissachatina fulica, has returned for another “visit” to the Sunshine State. The species is native to East Africa, but has been introduced to many other parts of the world via the pet trade, as a food resource, and by accidental introduction, most likely with ornamental plants. Authorities believe that the current invasion, first detected in New Port Richey, Pasco County, results from the illegal pet trade. Giant African Snails first invaded the Miami area in 1966, and w

Shell of the Week: The Keys Top Snail

Calliostoma adelae Schwengel, 1951 reaches about 40 mm in height, and has a moderately wide spire angle. The shell sculpture consists of finely beaded spiral cords that alternate with narrower threads in the last shell whorls. There are about 2–3 cords with larger, lighter-colored beads above the suture (the boundary between two whorls), the umbilicus is moderately large, umbilicus wall cream-colored, bordered by one larger-beaded cord. The shell color is yellowish-brown, with a pattern of diffu