When we speak of shellfish, we are referring primarily to a group of bivalve mollusks (oysters, mussels, clams, and cockles) which ingest food by a process termed filterfeeding. This process involves the selective ingestion of small particles of organic matter from large volumes of water drawn into the shellfish in the form of currents. As potential food particles travel across the animal’s gills, they become entrapped by mucus strands secreted continuously by the shellfish during pumping. The string-like masses of food material and mucus are directed by ciliary action to the mouth region where the matter is sorted. According to its nature, the entrapped material may be swept, via ciliary action, directly into the mouth or along rejection paths to the outside.9,45,142 Due to this method of feeding, it is possible for shellfish to accumulate any organic matter suspended in the over-lying water, including such small particles as viruses and bacteria. Hence, shellfish residing in waters receiving sewage pollution can accumulate enteric pathogens and serve as vectors of enteric diseases.