Order

Cardiida

  Class

Bivalvia

  No. of Genera in Ref.

  No. of Species in Ref.

  Environment

Fresh : No | Brackish : Yes | Marine : Yes

  Aquarium

  First Fossil Record

     

  Remark

Changed Order from Veneroida to Cardiida (Ref. 3477). Shell inequilateral, ovate to subelliptical or trapezoidal in outline, laterally compressed, somewhat gaping, equivalve to feebly in equivalve because of a slight posterior flexure. Umbones not very prominent, generally near the midline of valves. Outer surface of shell smoothish or with a mainly concentric sculpture, sometimes also with developed radial elements on whole shell or on posterior slope only. Periostracum generally conspicuous, horny, and dehiscent. Ligament external and prominent, attached behind umbones on projecting nymphs. Hinge with 2 small cardinal teeth in either valve; lateral teeth absent. Interior of shell porcelaneous. Two adductor muscle scars, unequal in shape. Pallial sinus deep. Cruciform muscle scars present, though often quite obscure. Internal margins smooth. Gills of eulamellibranchiate type, with folded branchial sheets; outer demibranch expanded above the ctenidial axis, but smaller than inner demibranch. Foot strong, laterally compressed, and pointed. Siphons naked, long, and separate to their base, with 6 lobes or tentacles at the end. Mantle margins papillate, fused ventrally, with a broad anteroventral opening. Deposit or suspension feeding animals, generally lying buried at an oblique angle to the surface, with tips of siphons reaching the sea bottom. Can actively burrow in soft substrates with their strong foot. Sexes separate. Development with a free-swimming larval stage. The most common species of Psammobiidae are often collected for food in southeastern Asian countries of the tropical West Pacific, and some are considered a delicacy (Ref. 348).

  Etymology

  Division

  Reproductive guild

  Typical activity level

  Main Ref.

  Coordinator