Donax is a genus of small, edible saltwater clams, marine bivalve mollusks. The genus is sometimes known as bean clams; however, Donax species have various common names in different parts of the world.
Species of Donax live, 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 filter feeders. Some species, such as Donax variabilis, migrate vertically and horizontally with changes in the tides.
The empty small (15 to 25 mm) 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 most shallow 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 (the so-called "dance of the coquina").
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