Pholadoideans

Pholadoidean is a superfamily of marine bivalve molluscs. These animals are commonly known as piddocks, rock borers, or date mussels. They are characterized by their elongated, often gaping shells that are adapted for boring into solid substrates. The shells are typically thin and fragile, and their surface sculpturing is often rough and adapted for abrasive action. Pholadoideans achieve their burrowing through a combination of mechanical abrasion with their shell valves and chemical secretions. They are found in a wide range of marine environments, from intertidal zones to the deep sea, and inhabit a variety of materials including soft rock, coral, and even wood.

The feeding method of pholadoideans is suspension feeding. They extend their siphons, which are often very long and can be united, out of their burrows to filter food particles from the water column. The siphons are typically protected by a thin, calcareous sheath. Pholadoideans play a role in bioturbation, altering the physical structure of the substrates they inhabit, and can be important in the ecological dynamics of rocky shorelines and coral reefs. Their boring activity can sometimes be considered a nuisance by humans, particularly when they bore into man-made structures or commercially valuable shell deposits. Reproduction in pholadoideans is generally sexual, with external fertilization. The larval stages are planktonic before settling and beginning their boring life stage.