page_title: Ark clam
section_title: Genera
hierarchical_section_title: Ark clam / Genera
caption_attribution_description: Coquillages à Fadiouth, Sénégal; bien connu sec, le 'pan' dans la cuisine Senegalese.
context_page_description: Ark clam is the common name for a family of small to large-sized saltwater clams or marine bivalve molluscs in the family Arcidae. Ark clams vary both in shape and size. They number about 200 species worldwide.
  The shells of ark clams are often white or cream, but in some species, the shell is striped with, tinted with, or completely colored, a rich brown. In life the shell of most species has a top shell layer that is thick brown periostracum affixed to the harder calcareous part of the shell. In some species such as Barbatia, this outer horny covering is tufted at the end of the shell into something that resembles a beard, hence the name Barbatia or bearded one.
  The group is known as "ark shells" because species such as Arca have a large flat area between the umbones which, in an undamaged shell, somewhat resembles a deck, with the rest of the shell perhaps illustrating an ancient wooden boat such as Noah's ark is thought to have been.
  All ark shells have a long straight hinge line with a single row of numerous small and unspecialized "teeth". This is known as a "taxodont dentition" and represents an ancient ancestor.
context_section_description: Genera within the family Arcidae include:
  Acar Gray, 1857
  Anadara Gray, 1847
  Arca Linnaeus, 1758
  Barbatia Gray, 1847
  Bathyarca Kobelt, 1891
  Bentharca Verrill and Bush, 1898
  Larkinia  Reinhart, 1935
  Samacar Iredale, 1936
  Senilia Linnaeus, 1758
  Tegillarca Iredale, 1939
caption: Numerous valves of arcids, genus Senilia, washed up on the beach in Senegal
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