Question

Like sponges and cnidarians, flatworms and roundworms get oxygen and get rid of carbon dioxide by

Answer 1

directly through their cuticle, which is permeable to both gases. Once oxygen has crossed into their bodies, it diffuses throughout the tissues.

Step-by-step explanation:

Answer 2

directly through their cuticle, which is permeable to both gases. Once oxygen has crossed into their bodies, it diffuses throughout the tissues.