Arca

Arca is a genus of marine bivalve molluscs belonging to the family Arcidae, commonly known as ark clams or ark shells. These bivalves are characterized by their robust, often rectangular shells with a prominent, tooth-like hinge structure. Ark clams are found in a wide range of marine environments, from shallow intertidal zones to deeper waters, and are distributed globally.

Arca ocellata

Noah’s Arch – Arca noae

Characteristics

Arca species exhibit a number of distinct characteristics that distinguish them from other bivalves. Their shells are typically heavy and solid, with a prominent, straight hinge line that is often ornamented with numerous teeth. The outer surface of the shell is usually covered with radial ribs, while the inner surface is often smooth and glossy. The foot of the ark clam is large and muscular, allowing it to burrow into sediment.

Ark clams are suspension feeders, filtering food particles from the water column using their gills. They are also capable of moving around using their muscular foot, although they are generally sedentary. Many species are known to form dense aggregations, particularly in intertidal habitats.

Environments

Ark clams are found in a wide range of marine environments, including:

  • Intertidal zones: Some species are well-adapted to the harsh conditions of the intertidal zone, where they can be exposed to fluctuating salinity, temperature, and wave action.
  • Subtidal zones: Other species inhabit the subtidal zone, where they are permanently submerged in water.
  • Sandy bottoms: Many ark clams live on sandy bottoms, where they bury themselves in the sediment using their muscular foot.
  • Rocky reefs: Some species can be found attached to rocks or other hard substrates.

Their distribution is global, with species found in all the major oceans.

References

For more information on Arca, please visit the following websites: