Bivalve

These animals include marine clams (cockles), edible and freshwater mussels, and inhabit a wide range of environments, from shallow coastal areas to the deep sea. In total, including fossil species, the number of bivalve species exceeds 15,000, occurring in both saline and freshwater habitats. They may live on sandy, muddy, or rocky substrates, or remain attached to hard surfaces.

Bivalves play a key role in natural water filtration, sediment stabilization, and creating habitats for other species. Many serve as a food source for humans and other animals, and they hold special significance in shellfish farming and aquaculture industries. The morphology of their shells is highly diverse, ranging from thick, sturdy shells that provide defense against predators to light and delicate shells adapted to calm waters.

Most bivalves are filter feeders; they draw water through their gills, extracting organic particles such as plankton and suspended matter.

Fossil bivalves not only reveal their evolutionary and ecological past but also provide valuable information about ancient environments and even the Earth’s climate millions of years ago. Particularly during the Cretaceous period, certain species served as important geological index fossils for determining the age of strata and reconstructing past environments.

Bivalves exhibit diverse responses to environmental changes; some species are highly resilient and widely distributed, while freshwater species today face threats from water pollution and dam construction.

Overall, bivalves were once valued mainly as geological indicators and sediment builders, whereas today, in addition to their role in aquatic ecosystems, they are of great economic importance through food production, pearl formation, and natural water purification.