Order

Cardiida

  Class

Bivalvia

  No. of Genera in Ref.

  No. of Species in Ref.

  Environment

Fresh : No | Brackish : No | Marine : Yes

  Aquarium

  First Fossil Record

     

  Remark

Shell variable in shape, usually elongate-ovate or suborbicular, rather thin and somewhat laterally compressed, often slightly inequivalve (with a rightwards flexure on posterior end). Umbones low. Outer surface often brightly coloured; sculpture not strong, chiefly concentric, sometimes feeble. Ligament external, arched, behind umbones. Hinge with 2 small cardinal teeth in either valve (1 of which is generally bifid); lateral teeth often present, generally better developed in the right valve, with the anterior lateral tending to be proximal to the cardinal teeth. Interior of shell porcelaneous. Two adductor muscle scars, the anterior more or less elongated, the posterior somewhat rounded or quadrate. Pallial sinus deep, sometimes of a different shape in the 2 valves, often largely confluent ventrally with the pallial line. Cruciform muscles leaving small paired round scars near the posteroventral end of pallial line. Internal margins smooth. Gills of eulamellibranchiate type, with smooth branchial sheets, the outer one raised and sometimes reduced. Foot strong, laterally compressed. Long, narrow, separate and mobile naked siphons, with 6 lobes on top. Cruciform musces present. Mantle margins widely open anteroventrally. Active burrowers of soft substrates in which they may constitute dense communities, sucking up organic matter from the sea floor with their long siphons. Lay frequently in a horizontal position within the substrate, with the left valve uppermost. Sexes generally separate. Development with a free-swimming larval stage. Tellins are collected for food by coastal populations in many areas, and their delicate and often colorful shells are frequently used to make decorative items (Ref. 348).

  Etymology

  Division

  Reproductive guild

  Typical activity level

  Main Ref.

  Coordinator