How do oysters and other shellfish filter water?

Filter-feeding shellfish such as oysters use their gills to strain suspended particles from water. As water passes through the body, food particles are trapped in mucus and directed to the mouth. This feeding method helps oysters grow while also improving water clarity in their habitat. The exact amount filtered varies by species, size, and conditions, so it is better to say oysters can process substantial volumes rather than a fixed universal number. Their role in ecosystems is important because reef-building shellfish can create habitat and influence water quality.