Digestive system: Clams feed theusing cilia. They catch food in sticky mucus and move it into the mouth via cilia. However, they only retain some ability to filter-feed and rely on their bacterial symbionts that live within their gills for the major source of their nutrition. The symbionts receive nutrients and oxygen, which flow into the clam through the uppermost end of the shell.
Circulatory system: The heart wraps around the intestine where the intestine emerges from the visceral mass. The heart consists of two parts, a thick-walled ventricle surrounding the intestine and two thin-walled auricles attached at either side of the ventricle. This is an excretory organ known as a nephridium. Nephridia remove metabolic waste products from the blood and release the waste into the mantle cavity near the excurrent aperture.
Nervous system: Clams have a typical bivalve nervous system containing three pairs of ganglia. There is the cerebral ganglia on the left and right sides of the esophagus, a fused pair of pedal ganglia at the base of the foot within the visceral mass and a pair of closely adjacent visceral (posterior) ganglia ventral to the posterior adductor muscle.
Reproductive system: They have what you call a gonad. The gonad is an integral part of the visceral mass positioned ventral and lateral to the digestive gland and loops of the intestine. The clam is either male or female and reproduces sexually.
Integumentary system: clams are protected by a hard shell made of calcium carbonate secreted by the mantle, a heavy fold of tissue that surrounds the mollusc's internal organs.
Clams live on bays and estuaries to approximately 15 meters in depth. They are generally found in mud flats and firm bottom areas consisting of sand or shell fragments. They can tolerate a wide range of salinities and live in brackish to saltwater conditions. . Clams have hatchet-footed, which makes them a mollusk.
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