Briefly describe the structure of the digestive system in roundworms. How does it differ from previous phyla covered in this course?
a. Roundworms have a simple, straight digestive tube with a mouth and anus. This differs from flatworms, which have a branching gut.
b. Roundworms have a closed circulatory system, which is a significant difference from other phyla in this course.
c. Roundworms have a gizzard for mechanical digestion, unlike other phyla with a single stomach.
d. Roundworms lack a digestive system entirely, relying on diffusion for nutrient absorption.
