Mollusks

The Atlantic Mud Piddock

The Atlantic Mud Piddock, Barnea truncata (Say, 1822) is a bivalve that bores into hard clay and soft rock. It will settle as a larva onto the host rock, and will grow as it bores into it. The resulting borehole is conical (with the narrow end toward the rock surface), and the Piddock ends trapped inside the rock for life. The Atlantic Mud Piddock is a close relative of the Angel Wing. Despite its very broad geographical distribution in the Atlantic Ocean (from Canada to Florida, Gulf of Mexico,

The Eastern Auger

The Eastern Auger, Terebra dislocata (Say, 1822), is the largest (reaching about 2.5” in length) and most abundant of the four species of Auger Snails living on the sandy shores of Southwest Florida. Augers are found in the sand close to the water edge, in medium- to coarse-sand habitats, where they feed on marine worms, using their teeth modified as barbs, in the fashion of cone snails, to inject venom into their prey. Photos by José H. Leal. #EasternAuger #Terebradislocata

The Variable Coquina

The Variable Coquina, Donax variabilis Say, 1822, is a small (usually a little less than one inch) and very common local clam that gets its name from the very broad range of colors displayed by the species, within a single population. (The sample shown in the photos was collected within an area of about one square foot on Captiva.) Scientists believe that this extreme polychromism confuses predators of this species, preventing shorebirds from memorizing clear search images of the small clams. Co

The Atlantic Nut Clam

The Atlantic Nut Clam, Nucula proxima Say, 1822, lives locally on muddy-sand bottoms. Most bivalves (Clams, Mussels, Oysters, etc.) are filter-feeders, “sieving” the water to collect their microscopic food (microalgae and other forms of phytoplankton). Nut Clams (family Nuculidae), on the other hand, are deposit-feeding bivalves, scooping up the film of decomposing organic matter and bacteria that accumulates on the surface of the sea floor. They do so using tentacle-like structures called labia

The Bruised Nassa

The Bruised Nassa, Nassarius vibex (Say, 1822), is a denizen of the mud flats and back-bays of Southwest Florida and other areas of the tropical western Atlantic. Its shell, measuring about 0.5 inch, is extremely variable, but typical of the species is the relatively broad shield that surrounds the shell opening, or aperture. Bruised Nassas are scavengers, feeding on the decaying corpses of other marine animals, including fish, horse crabs, crabs and other crustaceans, to name just a few. [The s

The Common Atlantic Slipper Snail

The Common Atlantic Slipper Snail, Crepidula fornicata (Linnaeus, 1758), is one of the most common gastropod shells found on the beaches of Sanibel and Captiva. Slipper Snails (family Calyptraeidae) have shells that resemble limpets, but can be distinguished from these latter by the internal “deck” or “shelf” that houses the bulk of the snail’s organs, and the “twisted” shell apex. Unlike most gastropods, Slipper Snails are suspension feeders, scooping-up plankton and other materials in suspensi

The Atlantic Carrier Snail

The Atlantic Carrier Snail, Xenophora conchyliophora (Born, 1780), is a moderately rare species in the barrier islands of Southwest Florida. Almost all members of the Carrier Snail family Xenophoridae have the ability to cement other shells, shell fragments, worm tubes, corals, and even little pebbles to their own shells. They hold the object to be cemented in place with their foot, then proceed to secrete shell material to affix the object permanently to their own shell edge. Some species speci

The Fargo Worm Snail

The Fargo Worm Snail, Vermicularia fargoi Olsson, 1951, is a gastropod with a shell that starts regularly coiled until it is about an inch long. From then on, the shell then becomes uncoiled, acquiring its typical, irregular shape. The shell “tube” is about 3/8” in diameter. Shells of the Fargo Worm Snail are fairly common along the beaches of Southwest Florida, and so are those of a close living relative previously portrayed in this column, the Florida Worm Snail, Vermicularia knorrii (Deshaye

The Atlantic Petricolid

The Atlantic Petricolid, Choristodon robustus (G.B. Sowerby I, 1834), is an inch-long clam belonging to the Venus Clam family Veneridae. The species is found from North Carolina to Brazil. Shells of other members of the Venus Clam family, such as the Southern Quahog, the Sunray Venus, and the Cross-barred Venus, to name a few, are commonly found along the beaches and bays of Southwest Florida. This is not the case with the shells of the Atlantic Petricolid: the species is present in the area, bu

The Sunray Venus Clam

The Sunray Venus Clam, Macrocallista nimbosa (Lightfoot, 1786), is one of the most attractive members of a very diverse family of bivalve mollusks, the Veneridae. Sunray Venus Clams have shells that vary in color from salmon-pink to brown to grayish-blue. The “Sunray” pattern on the valves is always asymmetrical, i.e, one valve is not a mirror image of the other. A prized shellfish item, the species is being farmed in captivity in parts of Southwest Florida, including Pine Island in Lee County.