Donax (bivalve)
Donax is a genus of small, edible saltwater clams, marine bivalve molluscs with highly variable color patterns. The genus is sometimes called bean clams or wedge shells; however, Donax species bear different common names in different parts of the world. In the southeastern United States, they are called "coquina", a word that is also used for the hard limestone concretions of their shells and those of other marine invertebrates.
Ecology
Species of Donax live in the swash zone, sometimes in high concentrations, vertically aligned in the sand on exposed beaches, on tropical and temperate coasts worldwide. When the waves wash these small clams out of the sand, they can dig back in again quite rapidly. They are phytoplankton filter feeders. They are an import source of food for crabs, fish and shorebirds. They are sensitive to environmental conditions and are considered an indicator of beach habitat health. Some species, such as Donax variabilis, migrate vertically and horizontally with changes in the tides. The genus enjoys a global distribution. These coquina clams are found extensively on the east coast beaches of Trinidad and widely available in Venezuela.Human use
Donax is an edible mollusk that has been consumed since pre-historic times and is still consumed today. Numerous recipes for coquina soup have been published. Recreational foragers should follow seafood safety guidelines and shellfish harvesting restrictions, and should be aware of any harmful algal blooms that may contaminate shellfish with biotoxins. In some parts of the world Donax clams are still gathered by indigenous people as an important subsistence food.Species
Species within the genus Donax include:Donax asper Hanley 1845Donax assimilis Hanley, 1845 Donax baliregteri Huber, 2012 Donax bertini Pilsbry, 1901 Donax bipartitus Sowerby III, 1892 Donax brazieri Smith, 1892Donax bruneirufi Huber, 2012Donax burnupi Sowerby III, 1894 Donax caelatus Carpenter, 1857 Donax californicus Conrad, 1837 Donax carinatus Hanley, 1843Donax clathratus Reeve, 1855 Donax culter Hanley, 1845Donax cuneatus Linnaeus, 1758 Donax denticulatus Linnaeus, 1758Donax dentifer Hanley, 1843Donax ecuadorianus Olsson, 1961 Donax erythraeensis Bertin, 1881Donax faba Gmelin, 1791Donax fossor Say, 1822 - was thought at one time to be a northern form of D. variabilisDonax francisensis Donax gemmula Morrison, 1971 Donax gouldii Dall, 1921 - The bean clam, aka Donax gracilis Hanley 1845 Donax hanleyanus Donax kindermanni Donax lubricus Hanley, 1845 Donax madagascariensis Wood, 1828Donax nitidus Deshayes, 1855 Donax obesulus Reeve 1854 Donax obesus d'Orbigny, 1845Donax oweni Hanley, 1843Donax paxillus Reeve, 1854 Donax punctatostriatus Hanley, 1843Donax rothi Coan, 1983Donax semistriatus Poli, 1795 Donax serra Röding, 1798 Donax simplex Sowerby III, 1897 Donax sordidus Hanley, 1845 Donax striatus Linnaeus, 1767 Donax texasianus Philippi, 1847 Donax townsendi Sowerby III, 1894 Donax transversus Sowerby I, 1825 Donax trunculus Linnaeus, 1758 Donax variabilis Say, 1822 - Known in Florida under the Spanish word "coquina", is the common and colorful Donax species of the southern Atlantic and Gulf shores from Virginia to the Caribbean. This species is locally abundant on beaches with fine sand from the mid-Atlantic coast to Texas.Donax variegatus Donax vellicatus Reeve, 1855 Donax veneriformis Lamarck, 1818 Donax veruinus Hanley, 1913Donax vittatusThe empty small shells of Donax variabilis and Donax fossor may be found washed up on the beach, especially at low tide. The living animals can often be seen where the waves wash the sand around in the shallowest part of the littoral zone as the tidal level changes. These clams can use the action of waves to move themselves up and down the beach, quickly burrowing into a new location before they can be swept away.