An earthworm's body consists of a number of fluid-filled compartments, each with its own set of longitudinal and circular muscles. But in the roundworm, a single fluid-filled cavity occupies the body, and there are only longitudinal muscles that run its entire length. Predict how the movement of a roundworm would differ from the movement of an earthworm.

Verified step by step guidance

1. Understand the anatomical differences: Recognize that earthworms have both longitudinal and circular muscles in each segment, while roundworms have only longitudinal muscles along the body.
2. Consider the role of muscle types: Longitudinal muscles generally contract the body, making it shorter and thicker, whereas circular muscles can elongate and thin the body when they contract.
3. Analyze the impact of muscle arrangement on movement: In earthworms, the combination of longitudinal and circular muscles allows for more versatile movements such as elongating, shortening, and bending in various directions.
4. Predict roundworm movement: Since roundworms lack circular muscles, their movement would primarily involve shortening and lengthening along their length, without the ability to significantly widen or narrow their body.
5. Compare movement capabilities: Conclude that earthworms likely have more complex and varied movement capabilities compared to roundworms, who may exhibit simpler and more restricted movement patterns.