Shells

The Enigma of Hidden Colors

Colors in animals are almost always linked to visual behaviors and species interactions. Bright colors and patterns on mollusks may help, for instance, attract a mate, warn a predatory fish of a foul-tasting or poisonous sea slug, or camouflage a snail against its habitat. We expect that most colors “serve a purpose” based on another animal, “friend or foe,” being able to see those colors. But what if pigments are present inside a clam shell, in an area that is never seen by another animal? Take

Shell of the Week: The Tellin Semele

Despite its name, the Tellin Semele is not a tellin, but is instead a semelid, like the clam presented last week, the Concentric Ervilia. Cumingia tellinoides (Conrad, 1831) reaches 15 mm (about 0.6 inch.) The prevailing color in this species is a dirty-white, but some shells may be slightly translucent. The shell sculpture consists of fine but well-defined growth lines, and the hinge consists basically of elongate lateral teeth and an internal ligament that rests inside a spoon-shaped chondroph

A Challenging, Striking Microgastropod!

Micromollusks* present a challenge to our efforts to visually document collection specimens. Take, for instance, the shell of Orbitestella aequicostata Raines, 2002 in the image below. That adult shell measures 0.66 mm (about 0.03 inch), and is a paratype, one of the individuals examined and referenced by Bret Raines in his original description of the species from Easter Island. (The normally whitish shell appears iridescent, as it had earlier been coated with metal for scanning electron microsc

Shell of the Week: The Disk Dosinia

Last week, we examined the Elegant Dosinia, Dosinia concentrica. Today I want to introduce its closest relative, Dosinia discus (Reeve, 1850). The two species have shells that are very similar in size (about 2.75–3 inches), in their circular shape, and white color, but the Disk Dosinia differs from its “sister species,” above all, by having twice as many commarginal (“concentric”) ridges, about 16–20 per centimeter (40–48 per inch). #veneridae #venusclam #commarginal #diskdosinia #dosiniadiscus

The Stylish Antillean File Clam

File clams (family Limidae) are marine bivalve mollusks with oval shells that resemble “distorted,” or asymmetrical, scallops. There about 130 species in the family. Most file clams are able to use their tentacles to engage in short bursts of irregular swimming, and some species can build cocoon-like nests for protection. The Antillean File Clam, Limaria pellucida (C.B. Adams, 1848), (photo) reaches 25 mm (about one inch), has a thin whitish shell, and relatively large, translucent tentacles fes

We’re Right-handed or Left-handed…

And so are shells! Snails have coiled shells, and most coil in the right-hand direction: if you look at the shell with its tip pointing up, the opening is on the right side. These are called dextral shells, in contrast to left-handed ones, called sinistral. It’s long been suspected that the coiling direction, also known as chirality, is determined by a single gene. This was confirmed recently by Japanese researchers Masanori Abe and Reiko Usuda. Using complex gene-editing technologies to induce

Shell of the Week: The Princess Venus

Periglypta listeri (J.E. Gray, 1838) is another member of the diverse venus clam family, the Veneridae (which includes the Southern Quahog, Cross-barred Venus, Sunray Venus, and many other local species). The Princess Venus grows to about 65 mm (about 2.5 inches), and differs from other local venus clams by the sharply truncated posterior margin (on left of images), which gives a quadrangular aspect to the shell. The sculpture is vaguely similar to that of the Lady-in-waiting Venus (Chionopsis i

Shell of the Week: The Angel Wing

Cyrtopleura costata (Linnaeus, 1758) is one of the local iconic species, forming, with the Lion Paw, Junonia, Scotch Bonnet, and Alphabet Cone, a “quintet of desirables” for collectors of Southwest Florida shells. Depending on the species, members of the family Pholadidae can burrow on rocks, woods, clay, mudstone, and other hard substrates, forming long cylindrical burrows. Angel Wings burrows in compacted mud and can reach about 180 mm (7 inches) in length. Their long siphons cannot be withdra

Smile for the Camera!

Before the lockdown, while at the Museum's new Beyond Shells exhibit, I caught one of the Wedge Sea Hares, Dolabella auricularia (Lightfoot, 1786), taking a break from munching on seaweed, and scraping the plexiglass tank wall with its radula, probably to nibble on microalgae. The radula, the light-colored, horseshoe-shaped structure in the photo, is the main feeding organ in a gastropod mollusk. The photo also shows the beginning of the alimentary canal (the darker cavity on top of the radula).

Shell of the Week: The Depressed Slipper Snail

Crepidula depressa Say, 1822 is a local member of the family Calyptraeidae. It is one of the “flat white slipper snails” whose identification is difficult without a glimpse at the soft parts. The species may attain 40 mm (1.6 inch) at most, but is most often found in the 25 mm (about an inch) size range. Unlike the Black-foot Slipper Snail, (Crepidula atrasolea, the “other” local flat, white slipper snail), the Depressed Slipper Snail has a yellowish-cream color on the foot and mantle. Their whi