Question

why sac like digestive system is considered as primitive to the tube like digestive system

Answer 1

Due to lackness of researching bt after that its clearly surely that is sac like structure e.g. J type sac like or bag like structure called stomach.

Answer 2

1. sac-like digestive system

• A sac-like digestive system has a single opening. Food travels into it through that, gets digested and excreta comes out of the same opening. For example, Platyhelminthes. This is also known as a digestive cavity.

1. Tube-like digestive system

• In a tube-like digestive system there are two openings. The food enters through one, gets digested and moves out of the other one in the form of excreta, after the digestion is done. Human beings have this type of a digestive system. this is also known as a digestive tract.