The absence of alimentary canal in the parasitic flatworm can be attributed to the fact that

Analyze the question The question asks why some parasitic flatworms, such as the tapeworm (Taenia), have no alimentary canal (digestive tract). The best explanation must link to how they obtain nutrients.

Explain the concept Tapeworms live in the small intestine of their host (humans, pigs, cattle). The host has already digested the food, so the intestine is full of soluble, ready-to-absorb nutrients like simple sugars, amino acids and fatty acids. Because of this, the tapeworm does not need its own mouth, gut or digestive enzymes. It absorbs the digested food directly through its body surface (the tegument), which is thin and has a large surface area because the body is long and flat.

Evaluate the options

• A. its body does not feed: Wrong. The worm does feed, but by absorption rather than ingestion.
• B. it has no enzymes: Not the reason. The absence of a gut is not due to a lack of enzymes. The worm simply doesn't need to digest food itself.
• C. its body absorbs digested food: Correct. This directly explains why a gut is unnecessary.
• D. it has suckers on the scolex: Wrong. Suckers and hooks are for attachment to the intestinal wall, not feeding.

Answer: C

Tip Remember the link: parasite in the gut → host digests the food → parasite absorbs it → no gut needed. In exams, "absorbs digested food through the body surface" is the key phrase for tapeworm nutrition. Also remember that suckers and hooks = attachment.