Solemyidae

Solemyidae is a family of primitive, small to medium-sized marine bivalve molluscs. They are commonly known as awning clams. They are found worldwide, primarily in soft sediments in shallow to moderately deep waters.

Solemyids are characterized by their elongated, thin, and fragile shells, which are covered by a dark periostracum, giving them a leathery or "awning-like" appearance. The shells are typically equivalve (the two valves are the same size and shape) and inequilateral (the beaks are not centrally located). The hinge is toothless.

These clams are unusual in that they lack functional gills and rely on chemoautotrophic bacteria that live within their tissues to provide them with nutrients. These bacteria oxidize sulfur compounds, deriving energy from the process, which is then used to fix carbon dioxide and produce organic matter that nourishes the clam. This symbiotic relationship allows solemyids to thrive in environments rich in sulfide, such as hydrothermal vents, seeps, and organic-rich sediments.

Their burrowing activity contributes to bioturbation in marine sediments, affecting the distribution of nutrients and oxygen.

Solemyidae is an ancient family with a fossil record extending back to the Paleozoic Era. This long evolutionary history makes them valuable for studying the evolution of bivalves and chemosynthetic symbiosis.