donax

Donax is a genus of small to medium-sized saltwater clams in the family Donacidae, commonly known as wedge clams or coquina clams. Species in this genus inhabit sandy shores and are found in warm and temperate coastal waters worldwide, with many species in the Atlantic and Indo-Pacific regions. They are typically common on exposed beaches and in tidal flats.

Members of Donax have shells that are generally oval to wedge-shaped and laterally compressed. The shells are usually smooth or lightly ribbed, and coloration varies among species from pale to dark, with some showing bands or blotches. Individual shells range from about 1 to several centimeters in length. Like other bivalves, they possess a hinge with teeth and a soft body inside.

Donax species are siphon-feeding filter feeders that live buried in sand, often in the upper to mid intertidal zone. They use their muscular foot to burrow and reposition themselves within the sediment, and they feed by drawing water through their siphons to extract plankton and organic particles. They are adapted to fluctuating moisture, temperature, and exposure typical of beach environments.

The best-known species is Donax variabilis, the coquina clam, common along parts of the Atlantic and Gulf coasts of North America. Other species occur in the Mediterranean, Indian, and Pacific Oceans, such as Donax trunculus. Some Donax are used as seafood or bait, though population levels can be affected by harvesting and habitat modification.

Taxonomically, Donax is the type genus of the family Donacidae, within the order Cardiida, class Bivalvia, phylum Mollusca.