Pholadoidean

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 thin, brittle shells which are often gaping at the ends. The shells are adapted for boring into soft rock, wood, or other substrates. Some species are also found free-living on the seabed.

The superfamily Pholadoidea contains two extant families: the Pholadidae and the Xylophagidae. The Pholadidae are the most diverse group, with many species known for their ability to bore into a wide range of materials. The Xylophagidae, on the other hand, are primarily wood-boring bivalves.

Pholadoideans are found in marine environments worldwide, from intertidal zones to deep-sea habitats. Their boring mechanism varies depending on the species and the substrate. Some use their shells to abrade the surface, while others secrete chemicals that soften the material. Once a cavity is created, the bivalve uses its siphons to filter feed on plankton.

Reproduction in pholadoideans is typically sexual, with external fertilization. The larvae are planktonic before settling and beginning their boring activity. Some species exhibit protandrous hermaphroditism, where individuals mature first as males and later change sex to become females.

Pholadoideans have ecological importance as bioeroders, playing a role in breaking down dead wood and shaping rocky shorelines. Some species can cause damage to wooden structures like piers and boats, leading to economic concerns. However, they are also a food source for some marine predators.