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Arks

Arks are boxy bivalves with thick, white, ribbed shells. They live in the salty waters of the lower Chesapeake Bay.

Three species of arks can be found in the Chesapeake Bay:

• Ponderous ark, Noetia ponderosa
• Blood ark, Anadara ovalis
• Transverse ark, Anadara transversa

Appearance:

• Thick, white, boxy shells with many ribs
• Ponderous arks are heart-shaped when viewed from the side
• Blood and ponderous arks are often covered with a thick, dark brown, felt-like periostracum
• The ponderous ark is the largest of the three species, growing to 2.5 inches long. The transverse ark is the smallest, growing to about 1 inch long.

Habitat:

• Usually burrow into bottom sediments
• Blood arks live in shallow waters, while ponderous arks live in both shallow and deep waters
• Transverse arks often do not burrow, but rather live among bay grass stems
• Use their large foot to firmly anchor themselves

Range:

• Found in the salty waters of the lower Chesapeake Bay

Feeding:

• Eat plankton and detritus
• Feed through a figure eight-shaped opening in the mantle

Reproduction and Life Cycle:

• Spawn throughout most of the year, with peaks in summer and autumn
• Gametes mature in the spring

Other Facts:

• Arks’ thick, heavy shells are able to withstand strong waves and currents
• Ark shells are often found washed up on lower Bay beaches
• The blood ark gets its name from its red blood. Most other bivalves have clear blood.

Sources and Additional Information:

• Life in the Chesapeake Bay by Alice Jane Lippson and Robert L. Lippson
• Ponderous Ark and Blood Ark – eNature
• Ponderous Ark – The Assateague Naturalist
• Ark Clams – Barnegat Bay Shellfish