Why does an earthworm require a muscular digestive tract when an ascaris does not?

An earthworm requires a muscular digestive tract to effectively process and grind the organic material it consumes from the soil, facilitating nutrient absorption. The muscular contractions help break down the food as it moves through the digestive system. In contrast, an ascaris, which is a parasitic roundworm, absorbs nutrients directly from its host's intestinal contents, making a complex muscular digestive system unnecessary for its survival. As a result, ascaris has a simpler digestive structure tailored to its parasitic lifestyle.