why is the flatworm digestive system called incomplete
The type of muscle in the digestive system is smooth muscle, one of  the types of involuntary muscles. Smooth muscle found in the  urinary bladder, gallbladder, arteries, ve â¦ ins, and the digestive  tract.onfidence votes 30. flatworms have incomplete digestive systems and they present extracellular and intracellular complementary digestions. They have sac like digestive system, one opening mouth and anus. Which means they're digestive systems aren't completely grown.