A doctor finds that a patient has a tapeworm, Taenia, picked up from undercooked pork.
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A doctor finds that a patient has a tapeworm, Taenia, picked up from undercooked pork. The worm is long and ribbon-like, with no mouth or gut. (a) To which phylum does it belong? (b) How does it hold on inside the intestine? (c) How does it get its food? (d) Which cells help it to remove wastes?
Need a reminder? The key ideaShow
Platyhelminthes: flattened, acoelomate, mostly parasites with hooks and suckers, flame cells, hermaphrodite; Taenia, Fasciola, Planaria (regeneration). Aschelminthes: round in section, pseudocoelomate, muscular pharynx, dioecious; Ascaris, Wuchereria, Ancylostoma. Annelida: metamerically segmented, coelomate, nephridia, closed circulation, double ventral nerve cord; Nereis has parapodia and is dioecious; Pheretima and Hirudinaria are monoecious.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The phylum. A flat body marks Platyhelminthes.
Step 2. Holding on. It has hooks and suckers on its head.
Step 3. Food. It takes in food already digested by the host directly through its body surface.
Step 4. Wastes. Flame cells help in excretion and osmoregulation.
Answer: (a) Platyhelminthes; (b) hooks and suckers; (c) through its body surface; (d) flame cells.
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