2. Obtain and similarly examine a whole mount of a planarian with an injected di

Question

2. Obtain and similarly examine a whole mount of a planarian with an injected digestive system. Identify the muscular pharyynx withen the pharyngeal pouch. The mouth is located at the free end of the pharynx. The mouth opens into the pharyngeal cavity, which in turn is continuous with the cavity of the intestine. To feed, a free planarian protudes the pharynx from its ventral (belly) side and sucks up organic morsels (insect larvae, small crustaceans, and other small living and dead animals). The intestine is elaborately branched and occupies much of the animal's body. What function does the extensive branching if the instestine facilitate?

Explanation / Answer

Planarians have an extensively-branched intestine.The intestine constitutes a single anterior and two posterior primary branches, from which secondary, tertiary, and quaternary branches offshoot towards the lateral margins of the animal body. The digestive systems of large planarians have more intestinal branches and occupy the greater area than small animals. Food passes from the mouth through the pharynx into the intestines where it is digested by the cells lining the intestines. The extensive branching of the intestine facilitates effective diffusion of nutrients to the rest of the body.

Related Questions

Navigate

• Browse (All)
• Browse 2
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.