Flatworms belong to the phylum Platyhelminthes, which have bilateral symmetry, are not segmented, and don't have a body cavity (they are acoelomates).
They lack specialized circulatory and respiratory organs, so they have flattened shapes that allow the diffusion of oxygen and nutrients. Their digestive system has only one opening, the mouth, that is used for both ingestion and egestion (the release of undigested residues).
Flatworms' digestive system has the following structures:
• Mouth
,• Pharynx
,• Intestine
On the other hand, the human digestive system is composed of:
• Mouth
,• Pharynx
,• Esophagus
,• Stomach
,• Small intestine
,• Large intestine
,• Anus
We can see that compared to the human digestive system, flatworms' digestive systems are much simpler, as they lack many of the specialized structures that are present in humans.
