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Phylum Platyhelminthes: Flatworms
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Kingdom:
Phylum:
Learning Objectives: *Refer to Kingdom Animalia Unit Plan
Text page: 372 http://www.ucmp.berkeley.edu/platyhelminthes/platyhelminthes.html *This is required
reading.
-Flatworms belong to the Phylum ______________________________, which means
____________________ in Greek. An appropriate name!
-Flatworms are different from other worms because they are ______________________________
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Platyhelminthes Habitat
-Free-living Flatworms live in __________________________________________________________,
whereas parasitic Flatworms live inside other animals (humans included!).
Platyhemlnithes Common Characteristics
1. There are over 18,000 known species of flatworms. They are grouped into Phyla Platyhelminthes
because they all share the following characteristics:
a) Symmetry/Cephalization
-Flatworms are the simplest animals with ____________________ symmetry.
-With the evolution of this new type of symmetry, Flatworms also show some _____________________.
For instance, in the Flatworm above has ____________________________________________________
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b) Level of Organization
-If Flatworms have specialized tissues working together for a common purpose, they have a ___________
level of organization.
c) Germ Layers
-The embryos of Flatworms have a third layer between the endoderm and the ectoderm. What is this
layer called? _____________________________________________
-Which tissues and organs develop from this layer?
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-With three germ layers, Flatworms are _____________________________________________________
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d) Coelom Development
-Flatworms are Acoelomate. This means that ________________________________________________
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Platyhelminthes Essential Functions
1. Circulation/Respiration
-Do Flatworms have specialized circulatory and respiratory systems?
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2. Digestion
-How many openings are there to the digestive
system?
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-What type of body plan do they have? _____________________________________________________
3. Movement
-How do Flatworms move?
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4. Reproduction
-Most flatworms are simultaneous hermaphrodites,
which means that they can ______________________
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Platyhelminthes Classes
*Take your own notes on each of the Platyhelminthes
classes from text page 372 to supplement what is below.
1. Class Turbellaria (Planaria)
-Common free-living marine and fresh water Flatworms,
accounting for 16% of all flatworms.
-Diet includes bacteria, algae and invertebrates.
-Some species have considerable powers of regeneration.
2. Class Cestoda (Tapeworms)
-Common parasite in mammals, obtained by eating
undercooked beef or pork.
-Show modifications to lifecycle/body plan for parasitism.
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3. Class Trematoda (Flukes)
-Endo and ectoparasites with modifications to life cycle and body plan for parasitism.
-Shistosoma is a blood fluke that causes the disease ______________________________________.
-Study the life cycle below:
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