Species Spotlight: Hard Clam
Hard clams are bivalve mollusks. Mollusks are a category of animals without a backbone (invertebrate) and bivalves are mollusks that are covered by two shells. Clams have many predators such as marine birds, rays, crabs, and humans. By contracting their adductor muscle, they can keep their shell sealed tightly to protect themselves.
Although their abundance may have declined since historical levels, the hard clam is considered a stable species. Hard clams are ecologically and economically important, not only are they commercially harvested for sale and consumption, but also play a significant role in recycling organic material in the water column and keeping our bays clean! Did you know CCE Marine Program is currently spawning and growing millions of shellfish for restoration purposes? Check out our Aquaculture Program to learn more!
Hard Clam
Mercenaria mercenaria
Hard clam shells are thick, grey to white in color, and have outer concentric growth rings.
Hard clams are filter feeders! They use a set of siphons for respiration and feeding.
Hard clam larvae under the microscope!
CCE Marine Program raises hard clams for restoration purposes!
Hard Clam
Scientific Name: Mercenaria mercenaria
Identification: Adult hard clams are just less than 3 inches, but can reach up to 5 inches. Hard clam shells are thick, grey to white in color, and have outer concentric growth rings. The inside of the shells are white with violet markings
Diet: Hard clams are filter feeders! They use a set of siphons for respiration and feeding on microscopic plankton, called algae, in the water column. They can filter up to 1 gallon of water per hour!
Habitat: Hard clams can be found throughout New England, north into Canada, and all down the Eastern seaboard of the United States. They inhabit both intertidal and subtidal areas.
Find this Species: Adult hard clams are sessile, meaning they stay in one place. However, they can burrow into the sediment using their strong muscular foot, leaving only their siphons exposed to feed. To find them, try digging beneath the surface in both intertidal and subtidal habitats!
Interesting Facts: Although their lifespan is generally unknown due to stress, evidence suggests clams may live as long as 40 years!
Hard clams prefer saline water and cannot survive if the salt content is too low.
Each female hard clam can produce between 1 and 5 million eggs during a spawning event!
After spawning, fertilized clam eggs become larvae within 12 hours and develop shells within 26-30 hours. After another 8-12 hours the veliger stage starts and the larvae become planktonic for 12-14 days.
Some hatchery raised hard clams have dark, zigzag stripes across the shell known as “notata”.
Watch this Marine Minute Monday to learn more about the hard clam!