1. Siphoning: Clams use their siphons to draw in water from the surrounding environment. The water enters the incurrent siphon, which is located near the front of the clam's body.
2. Filtering: As the water passes through the incurrent siphon, it is filtered by the clam's gills. The gills are covered in tiny cilia that trap food particles, such as plankton, algae, and other organic matter.
3. Ingestion: The filtered water, along with the trapped food particles, is directed towards the clam's mouth. The mouth is located on the ventral side of the clam, near the base of the siphons.
4. Esophagus: From the mouth, the food particles enter the esophagus. The esophagus is a short, muscular tube that leads from the mouth to the stomach.
5. Stomach: The stomach is a sac-like organ where the initial digestion of food takes place. The stomach contains digestive enzymes that break down the food particles into smaller molecules.
6. Intestine: From the stomach, the partially digested food moves into the intestine. The intestine is a long, coiled tube that runs from the stomach to the anus. The intestine is lined with microvilli, which are tiny finger-like projections that increase the surface area for absorption of nutrients.
7. Digestive diverticula: Clams also have specialized structures called digestive diverticula that branch off from the intestine. The digestive diverticula contain digestive enzymes that help break down specific nutrients, such as carbohydrates and proteins.
8. Absorption: As the food moves through the intestine, nutrients are absorbed into the clam's bloodstream through the walls of the intestine and digestive diverticula.
9. Egestion: The undigested remains of the food, along with waste products, are expelled from the clam's body through the anus. The anus is located near the excurrent siphon, which is the opening through which water is expelled from the clam's body.
This process of food movement and digestion allows clams to extract essential nutrients from their diet and convert them into energy for growth, reproduction, and other bodily functions.