Final answer:
In earthworms, the alimentary canal begins with the mouth and ends with the anus. Food moves sequentially through the esophagus to the crop, then the gizzard, and finally through the intestine where nutrients are absorbed before waste is expelled as castings.
Step-by-step explanation:
Earthworms possess a more advanced digestive system known as the alimentary canal, which starts with the mouth and ends with the anus. After ingestion, food moves through a series of specialized organs. First, the food enters the mouth, where it is taken up by the earthworm. Then, it travels through the esophagus, which is just a tube connecting the mouth and the next organ.
The food is temporarily stored in the crop, a storage organ, before moving into the gizzard. The gizzard functions to physically grind the food with the help of small particles and muscular contractions. After the gizzard, the food enters the intestine, where nutrients get absorbed. The earthworm’s body expels any remaining waste material as feces or castings through the anus. Complete digestion involves organ specialization and inter-organ cooperation, allowing earthworms to ingest continuous meals, digest food, and dispose of wastes efficiently.