The planaria is a free living flatworm that feeds on small animals. It had a simple alimentary canal with one opening , the mouth, on the ventral side of its flat body. The mouth opens into a short buccal cavity which leads into a large muscular pharynx.
The pharynx can be extended out of the mouth during feeding. The pumping action of the pharynx sucks in pieces of food which enter the pharynx and pass into the small intestine. The small intestine has three branches, one leading forward to the head end and the other two towards the the tail end. The branches give off numerous side branches.
Digestion is partly extracellular and partly intracellular as in Hydra. The branched intestine enables the digested food to diffuse to all parts of the body. Undigested food is egested from the mouth.
No comments:
Post a Comment