Phylum Flatworms
Answers are for parents and teachers.
1
Compare planarian and hydra: symmetry, layers, gut.
Hydra: radial, 2 layers, gut cavity only. Planarian: bilateral, organs and tissues more developed, branched gut.
2
Write the stages of the liver fluke’s life cycle in order.
Egg → ciliated larva → larvae in the snail → tailed larva → cyst → adult worm in the definitive host.
3
Write 3 rules to avoid the beef tapeworm.
Cook meat thoroughly; eat only inspected meat; wash hands. If infection is suspected, see a doctor.
4
Which organs became simpler through adaptation to parasitism?
Digestive and sense organs are simplified or lost; reproductive organs are strongly developed.
5
Why must liver fluke eggs reach water?
The ciliated larva hatches in water and finds a snail; without water development cannot continue.