Solemyids

Solemyids are a family of marine bivalve mollusks. They belong to the order Solemyida, and are characterized by their unique shell structure and habitat. Unlike many bivalves, solemyids possess equivalve shells, meaning both valves are of equal size and shape. These shells are typically thin, fragile, and covered with a dense layer of periostracium, a tough organic material. This periostracium is often extended into numerous fine, hair-like filaments that can reach lengths several times that of the shell itself.

These filaments play a crucial role in the lifestyle of solemyids. They are used for anchorage in soft sediments, such as mud or sand, allowing the bivalves to remain stable in their environment. Solemyids are infaunal, meaning they live buried within the seafloor. They are often found in deep-sea environments, but some species inhabit shallower waters.

A distinctive feature of solemyids is their symbiotic relationship with chemosynthetic bacteria. These bacteria live within the solemyid's gills, which are greatly enlarged to accommodate them. The bacteria are able to derive energy from chemical compounds, such as hydrogen sulfide, present in the surrounding environment, and in turn, provide nourishment to their host. This adaptation allows solemyids to thrive in environments where food may be scarce.