Gaseous exchange in annelids is more advanced and efficient compared to flatworms because?
the cells of their epidermis have no blood capillaries
they have well developed respiratory structures
their cylindrical shape gives high surface area to volume ratio
their surface area to volume ratio is very low
Correct answer is C
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.