Eulamellibranchs

Eulamellibranchs are a major subclass of bivalve mollusks. This group encompasses the vast majority of commonly known bivalves, including oysters, clams, mussels, and scallops. Their defining characteristic is the structure of their gills, which are large and plate-like, hence the name "eulamellibranch" which literally translates to "well-plated gills." These gills are used not only for respiration but also for filtering food particles from the water.

A key feature of eulamellibranchs is the presence of two strong adductor muscles that close their shells. These muscles are typically of unequal size, with one being larger than the other. Many eulamellibranchs are sessile, meaning they attach themselves to substrates or burrow into the sediment. Their feeding strategy relies on siphons, which are tube-like structures that draw water in for respiration and filter feeding and expel waste.

The diversity within the eulamellibranch subclass is enormous, with species found in nearly every aquatic environment, from freshwater lakes and rivers to the deepest ocean trenches. Their ecological roles are significant, often acting as filter feeders that help maintain water quality and as a food source for a variety of predators. Fossil evidence shows that eulamellibranchs have a long evolutionary history, dating back to the Paleozoic era.