Bittersweet Clam: Family Glycymerididae
The Bittersweet clam shells are common on my beach and Florida beaches. They are bi-valves somewhat related to Ark shells but are round. The two predominat types are the Giant Atlantic Bittersweet and the Spectral Bittersweet. Two other types in my collection, the Combs Bittersweet and the Spiny Papercockle/Square Papercockle shells are sometimes found on S. Hutchinson Island beaches. The papercockle shells resemble the purple semele shells except they thin ribs extending from the umbo. The Giant Bittersweet may reach 5" in size and is round with a beaked umbo. It's a white shell that features intricate brown patterns circling around the umbo and extending toward the bottom. Smaller versions of the shell (1/2' or smaller) have more intense patterns. The Spectral Bittersweet clam shells (around 1/2 to 1") are attractive for their patterns of brown and white. Spectral Bittersweets are round shells and range from dark brown to pure white.
Spectral Bittersweets
There is a variation of the bittersweets that is white with gray (sometimes almost blue) concentric lines and paterns which needs further study. The Spectral Bittersweets are sometimes pure white with a touch of brown on the insdie of the umbro or dark brown with concentric lines around the umbro. A range of solid shades from whitwe to brown may be found. The somewhat rare gray shells are off-white with bands of gray around the umbro.
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Family Glycymerididae
Glycymeris americana
(DeFrance, 1826)
Giant Bittersweet
Shell size to 100 mm; shell large, almost circular, compressed. Umbones at midpoint of hinge. Hinge teeth reduced under umbones. Sculpture of numerous low ribs. Margins of valves crenulated. Color white-gray, drab-gray, or tan, seldom with rusty-brown markings.
Family Glycymerididae
Glycymeris spectralis
Nicol, 1952
Spectral Bittersweet
Shell size to 30 mm; shell elliptical, compressed. Sculpture of 30-40 flat, low ribs. Hinge teeth about 10 on each side. Color ochre- to greenish-brown. Differs from Glycymeris pectinata by more elliptical shell, larger number of ribs, and uniformly brownish color.
Spectral Bittersweet Clam Glycymeris spectralis
Glycymeris spectralis Nicol, 1952
spectral bittersweet
Glycymerididae, often misspelled as Glycymeridae, common names dog cockles or bittersweets, is a worldwide family of salt water clams, marine bivalve mollusks in the order Arcida. They are related to the ark clams. This family contains 45 extant species in four general.
American Bittersweet:
Big and Solid
By Patricia B. Mitchell.
The American Bittersweet varies in size depending upon whether it lives in cooler or warmer water. In the southern section of its range the bivalve may reach a length of almost 5 inches (it is sometimes called the Giant American Bittersweet), whereas in the more northern reaches of its range it is only about ½-inch long. Usually a beachcomber will find only one valve of this mollusk, rather than both halves of the shell.
The circular, somewhat compressed shell is a dull, creamy white, mottled with yellowish-brown. It has low, rounded radial ribs. The beak points straight down. The hinge is slightly curved with a row of hinge teeth. The teeth are faint or there are none at all directly below the beak. The posterior muscle scar usually has a built-up shelly ridge, and there is no pallial sinus. The inner margins of the shell are slightly crenulate (serrated-looking). The valves are solid and definitely would not be thought of as fragile or thin.
The American Bittersweet Clam lives, burrowed in gravel or sand, in moderately shallow water from Virginia to Texas and Brazil. There are approximately 150 species of Bittersweets worldwide.
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Glycymeris gigantea (giant bittersweet clam) 1
Glycymeris gigantea (Reeve, 1843) - giant bittersweet clam (exterior surface) (public display, Bailey-Matthews Shell Museum, Sanibel Island, Florida, USA)
Bivalves are bilaterally symmetrical molluscs having two calcareous, asymmetrical shells (valves) - they include the clams, oysters, and scallops. In most bivalves, the two shells are mirror images of each other (the major exception is the oysters). They occur in marine, estuarine, and freshwater environments. Bivalves are also known as pelecypods and lamellibranchiates.
Bivalves are sessile, benthic organisms - they occur on or below substrates. Most of them are filter-feeders, using siphons to bring in water, filter the water for tiny particles of food, then expel the used water. The majority of bivalves are infaunal - they burrow into unlithified sediments. In hard substrate environments, some forms make borings, in which the bivalve lives. Some groups are hard substrate encrusters, using a mineral cement to attach to rocks, shells, or wood.
The fossil record of bivalves is Cambrian to Recent. They are especially common in the post-Paleozoic fossil record.
The giant bittersweet clam shown above is part of the Panamic Province: "Much richer in species than its Caribbean counterpart, the tropical-water Panamic area extends from the Gulf of California, along the Pacific coast of Central America to Ecuador. Known for its wide tidal ranges, its sandy-mud shores and offshore waters abound in colorful murexes, cones, olives and cowries. Over 2,500 species are known from here, including the endemic tent olive." [info. from museum signage]
Classification: Animalia, Mollusca, Bivalvia, Pteriomorphia, Arcoida, Glycymerididae