According to Yahoo!Education, an Annelida's digestive system revolves around a muscular gizzard and calciferous glands. Most annelids have soil diets and the gizzard grinds ingested soil to draw out the organic matter that the worm feeds on. Annelids that don't have soil diets still make use of a gizzard to assist in nutrient absorption. All annelids have calciferous glands that remove excess magnesium, strontium, phosphate and calcium from the ingested matter.Continue Reading
Yahoo!Education explains that an Annelida has a mouth under its head that leads to a simple digestive tract including an esophagus, pharynx and intestine. The Annelida's digestive tract also has a crop, which is a thin-walled storage area that shares similarities with a stomach. Most annelids burrow into the ground and swallow tiny pieces of matter along the way. After the Annelida's gizzard has helped it absorb nutrients from the ingested matter, the leftover waste passes through its body. In most annelids, excretion occurs from a pair of tubes inside each segment.
This process is beneficial to the annelid's ecosystem, according to Wikipedia. Earthworms aerate and enrich the soil. Marine annelids enable oxygen and water to penetrate the sea floor as they burrow into it. Annelid digestive systems also remove toxins from the soil and sand.Learn more about Worms