Family Cardiidae - cockles

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Bivalvia
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  Environment
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Fresh : No | Brackish : No | Marine : Yes
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Shell equivalve, inflated, oval to subtrigonal or subquadrate, often with a posterior ridge or angulation; sometimes very compressed anteroposteriorly, and heart-shaped when viewed from the anterior side. Umbones prosogyrate to orthogyrate, prominent, approximate. External sculpture mostly radial, often more or less differing on posterior slope. Periostracum usually weak to inconspicuous, rarely well developed. Ligament external, a short and prominent arched band behind the umbones. Hinge characteristics, with teeth curving outwards rather than being set on a flat hinge plate; 2 cardinal teeth, and anterior and posterior lateral teeth, typically present in each valve; cardinal teeth cruciform in arrangement, when valves interlock. Two subequal adductor muscle scars. Pallial line without a sinus. Internal margins with crenulations, generally corresponding with the outer sculpture. Gills of eulamellibranchiate type, folded, with dorsoventrally slanting axis. Foot strong and long, sickle-shaped. Mantle widely open ventrally, smooth or papillate, sometimes with marginal eyes. Siphons naked, short and separate, papillate on top. Shallow burrowers in sandy to muddy bottoms, most common in littoral and shallow subtidal waters. The geniculate foot can be used for jumping to escape predators. Sexes generally separate. Development with a free-swimming larval stage. In the tropical West Pacific, cockles are mainly collected for their shells, which are used as decorative items in local shellcraft. They are also eaten by coastal people and occasionally appear in local markets (Ref. 348).
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Ref.
[ e.g. 9948]                       
Glossary
                    [ e.g. cephalopods]


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