Ark clam

Ark clam
Arca zebra shell.
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Bivalvia
Subclass:	Pteriomorpha
Order:	Arcoida
Family:	Arcidae Lamarck, 1809
Genera
See text

Ark clams is the popular 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, and number about 200 species world-wide.

The shell of ark clams is often white or cream, but it is striped with or tinted with a rich brown color in some species.

The group is known as ark shells because some genera have a large flat area in front of the umboes, which, in an intact shell can somewhat ressemble a deck, with the rest of the shell perhaps ressembling an ancient keeled boat such as Noah's ark.

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 and ancient lineage.

The thick outer skin or periostracum of an ark clam can act as camouflage, matching its surroundings, such that the shells can sometimes look like stones when lying on the bottom.

Large ark clams, such as Arca zebra, are commonly used as bait, as well as food, throughout the Caribbean.

Genera

• Acar Gray, 1857
• Anadara Gray, 1847
• Arca Linnaeus, 1758
• Barbatia Gray, 1847
• Bathyarca Kobelt, 1891
• Bentharca Verrill and Bush, 1898
• Noetia
• Samacar Iredale, 1936
• Scapharca
• Senilia
• Trisidos

External links

• ITIS
• Archerd Shell Collection, Ark clams