Gaseous exchange in annelids is more advanced and efficient compared to flatworms because?
Answer Details
In simple organisms, such as cnidarians and flatworms, every cell in the body is close to the external environment. Their cells are kept moist and gases diffuse quickly via direct diffusion. Flatworms are small, literally flat worms, which “breathe” through diffusion across the outer membrane. Annelids have a closed circulatory system; the blood is entirely contained in vessels. Annelids have no lungs, although many species have simple gills.