Mollusks

The Banded Tulip

The Banded Tulip, Cinctura hunteria (G. Perry, 1811), is one of the largest and most attractive marine snails found along the barrier islands of Southwest Florida. The species, which may reach in excess of 4 inches in size, is also present in other parts of the Gulf of Mexico, eastern Florida, and northern Caribbean Sea. The smooth, tulip-shaped shell is characterized by the widely spaced, brownish spiral lines set against a light gray background color. The species is related to the True Tulip,

The Ponderous Ark

The Ponderous Ark, Eontia ponderosa (Say, 1822), is one of the most common shells found on the beaches of Sanibel and Captiva islands. One of the most striking features of this species is its dark-brown or black, velvet-like periostracum, the organic shell layer that covers part or the entire shell. Visiting beachgoers often confuse the periostracum of the Ponderous Ark for a layer of oil or tar that could have deposited on the white shell. Another feature that sets the Ponderous Ark apart from

The Tiny Dwarf Olive

The Tiny Dwarf Olive, Olivella pusilla (Marrat, 1871), is a local species found in relative abundance on sandy-mud bottoms and mud flats. Dwarf Olives used to be united with “normal-size” Olives in the family Olividae, but details of the anatomy and DNA separate them into their own family, the Olivellidae. The shell is up to 8 mm (about ¼ inch) in size, bullet-shaped, with about 5 whorls, and short spire. The color pattern in this species is very variable, but usually includes a cream, grayish,

The Pitted Murex

The Pitted Murex, Favartia cellulosa (Conrad, 1846), is one of the less-known Murex drills in Southwest Florida. Its shell may be pure white or whitish with brown undertones. The Pitted Murex derives its name from its shell sculpture. The shell surface is sculpted with apparent small pits, which closer inspection reveals to consist of a lace-like, interwoven pattern. One of the features of the shell in this species is the presence of varices, the wing-like expansions that repeat themselves at re

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