Order

Lucinida

  Class

Bivalvia

  No. of Genera in Ref.

  No. of Species in Ref.

  Environment

Fresh : No | Brackish : No | Marine : Yes

  Aquarium

  First Fossil Record

     

  Remark

Changed Order from Veneroida to Lucinida (Ref. 3477). Shell generally equivalve, lenticular and rounded to substrapezoidal, slightly inequilateral, not gaping. Umbones small and low, prosogyrate, about the midline of shell. Lunule small, often impressed and asymmetrical. Outer sculpture with concentric and/or radial components. Periostracum sometimes scaly and dehiscent. Ligament external, more or less deeply sunken in a groove of posterodorsal margin. Hinge typically with 2 cardinal teeth, and anterior and posterior lateral teeth in either valve; some or all of the hinge teeth sometimes reduced to absent. Two adductor muscle scars, the anterior narrowly elongate, frequently with an oblique ventral lobe detached from pallial line. No pallial sinus. Internal margins smooth or finely crenulate. Gills of eulamellibranchiate type; inner demibranch large, smooth or weakly folded, outer demibranch reduced to absent. Foot long and worm-like, with a mucous gland at the more or less inflated extremity. Mantle with a broad anteroventral gape, a posterodorsal exhalant siphonal tube and a rounded posterodorsal inhalant aperture. Pallial margin not papillate, often with an anteroventral accessory mantle gill. Burrowing, detritus-feeding animals, in which the inhalant siphon is usually replaced by an anterior tube lined with mucus and constructed within the substrate by the extensible, worm-like foot. The Lucinidae typically occur in sulphide-containing reduced sediments. The presence of the respiratory pigment haemoglobin enables them to live in these habitats of low oxygen concentration. Symbiotic, sulphur-oxydizing chemautotrophic bacterias are frequently housed in their thick gills and make a substantial contribution to their nutrition. Some of the larger and most common species are artisanally fished in some areas, and appear frequently in local markets, notably in the Philippines (Ref. 348).

  Etymology

  Division

  Reproductive guild

  Typical activity level

  Main Ref.

  Coordinator