Heterodonta

Order MYTILOIDA

Brachidontes exustus - Scorched Mussel

Morphology: Thin, fan-shaped shell with fine radial ribs. Color ranges from blue grey to yellow to blackish brown; interior has purple-brown splotches and hinge teeth numbering 1 to 4. 10-46 mm in length.

Distribution: New Jersey to Florida, the Gulf of Mexico, Caribbean, and South America down to Argentina.

Habitat: Intertidal on rock surfaces, also strongly associated with oyster reefs and mangroves. It can often be found washed ashore with other shells and seaweed. It has a high tolerance for salinity and temperature changes.

Life History: They have separate sexes and spawn in the spring and fall with the larva being quick developers. They are filter feeders.

Reference: Smithsonian Field Station at Fort Pierce

Geukensia demissa - Ribbed Mussel

Morphology: Shell ribbed and oval in shape. Two valves equal in size. Shell color brown to black, with some yellow or green tints. Can grow to 10 cm.

Distribution: Along United States east coast, from Gulf of Maine to Gulf of Mexico. Introduced to San Francisco Bay area.

Habitat: Intertidal oyster reefs and marsh habitats; can handle salinities as low as 6 ppt and as high as 70 ppt.

Life History: Filter-feeding bivalves. Dioecious, spawn once annually. Can live for 15 years.

Reference: Smithsonian Field Station at Ft. Pierce

Order Veneroida

Mercenaria mercenaria - Northern Quahog

Morphology: Solitary bivalve. Shells asymmetrical and slightly elliptical in shape. Two valves equal in size. Colors range from light brown to grey in color and shell possesses growth rings radiating out from the hinge. Can be up to 150 mm.

Distribution: Along east coast of the North America, from the Gulf of St. Lawrence to the Gulf of Mexico.

Habitat: Generally found buried in sandy or muddy habitats. Prefer waters with salinities ranging from 20-35 ppt and depths less than 10 m.

Life History: Commercially important filter-feeding bivalve. Protandric hermaphrodites, with juveniles being primarily males. Live to 46 years.

Reference: Smithsonian Field Station at Ft. Pierce

Polymesoda caroliniana- Carolina Marsh Clam

Morphology: Usually greenish to brownish in color with a fat, round shell of ~2.5 cm. Usually eroded around the umbo.Distribution: Virginia to Florida; Texas and Gulf of Mexico.Habitat: Found in muddy, warm areas of fresh to brackish waters, usually near the mouth of a river. Also common in poorly flooded Juncus marshes, but adults can withstand long periods of desiccation once established. Shell found in Ft. Johnson Saltmarsh.Life History: Lives on the surface of muddy bottom habitats and is a non selective filter feeder. Primarily spawn during the fall.Reference: Atlantic Seashore, Seashore Animals of the Southeast, Duobinis-Gray and Hackney, 1982.Photo:CalPhotos

Raeta plicatell - Channeled Duck Clam

Morphology: A molluscan bivalve reaching about 3 inches as an adult, the shell is pure white with prominent, wide, evenly spaced concentric ridges. The hinge has a large spoon shaped depression and the valve halves gape slightly at the ends.

Distribution: From the lower eastern United States, through the Gulf of Mexico and Caribbean to Venezuela. Found at Grice Beach.

Habitat: Resides in sandy mud in shallow waters at a depth of 0 to 11m.

Life History: Suspension feeder.

Spisula raveneli - Southern Surfclam

Morphology: Largest bivalve in the Western Atlantic. Shells are thick, slightly triangular, have rounded edges, concentric ridges, and a yellowish white color.

Distribution: Western Atlantic waters south of Cape Hatteras.

Habitat: Beds can be found from beach zones to 47m, but adults prefer turbulent waters in the breaker zone. Also found in estuarine waters.

Life History: Important commercial species that reach harvestable size (~5in.) in 5-7 years. Spawning is used for reproduction. Fertilization occurs in the water column after eggs and sperm are released above the bed then after about 3 weeks larvae settle on the bottom.

Reference: NOAA

Tagelus plebeius - Stout Razor Clam

Morphology: Burrowing bivalve mollusk. Shells of dead clams are chalky, dull and whitish; live clams have thin brownish-yellow covering over the shell (periostracum). Shells can reach 4 inches in length and about 1 inch in width and are elongate and semi-cylindrical.

Distribution: Western Atlantic, Massachusetts to the Gulf and to Brazil

Habitat: Intertidal to shallow subtidal, in muddy sand or mud. Prefer warm seas.

Life History: Infaunal eurihaline suspension-feeder that inhabits permanent burrows up to 70 cm in depth. Possess long siphons.

Reference: ITIS

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