Science Related Question?

Question

I am not sure what my teacher is wanting, I cant find anything for this question. What major adaptation occured in roundworms and how is that adaptation significant?

Answer 1

I think the big step forward for roundworms is that they have a complete digestive system with two body openings, the mouth and the anus.

This type of digestive system is a distinct advantage because roundworms can eat more food while they're still working on food they ate previously - can have food in different stages of digestion at the same time. That's very efficient in comparison with an incomplete digestive system with only one body opening.