The digestive system of flatworms is incomplete, not fully
developed, yet more advanced than in any other simple livings, therefore, they complete
their digestion by means of extracellular and intracellular
activity.
The complete digestive system of the flatworms
consists of mouth, a tube similar to pharynx and the intestine that could be branched to
enlarge the area of absoption of nutrients. We notice that the dygestive system presents
a single opening, therefore the wastes are eliminated through the same place the food
enters into the pharynx, such as, in flatworms, the mouth plays also the role of
anus.
There is another complementary way through flatworms
excrete materials that they do not need anymore, namely flame
cells.
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