Lunule (bivalve)

A left valve of a juvenile Mercenaria campechiensis viewed from the top to show the brown-tinted lunule on the right, next to the forward facing beak.

A lunule (from the Latin meaning small moon or crescent moon) is an anatomical feature which is found in the exterior surface of the shells of some species of clams, bivalve mollusks, as for example in the family Veneridae and in the genus Ascetoaxinus.

The lunule is a well-defined area near the hinge line of the shell, anterior to the beaks.^[1] Despite the name, a lunule is not always in the shape of a crescent moon. Details of the lunule are sometimes an important diagnostic feature in identifying a bivalve shell.

A right valve of Chionopsis intapurpurea viewed from the top to show the brown-tinted lunule.

References

↑ Website conchs.org, The Conchological Society of Great Britain and Ireland, Molluscs, Glossary, Advanced glossary of molluscan terminology, Lunule, by Steve Wilkinson, 5 November 2012 Accessed 2014.12.9

Bivalve anatomy

Shell	Callus Hinge line Hinge teeth Ligament Lira Lunule Nacre Pallial line Pallial sinus Periostracum Prodissoconch Resilifer Resilium Sculpture Umbo Valve Beak Annuli

Other hard parts	Byssus Pearl Sea silk

Soft parts	Adductor muscles Ctenidium Gastric shield Mantle Nephridium Siphon

Other	Abductin Glochidium Pseudofeces Trochophore Veliger

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