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Top 10 New Species 2008!. Top Ten. Phylum Platyhelminthes. Biology 11. General Characteristics. About 20 000 species Simplest animals with bilateral symmetry Can move forward in certain direction Have organs and organ systems. 3 Classes. Flukes: class trematoda
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Top 10 New Species 2008! • Top Ten
Phylum Platyhelminthes Biology 11
General Characteristics • About 20 000 species • Simplest animals with bilateral symmetry • Can move forward in certain direction • Have organs and organ systems
3 Classes • Flukes: class trematoda • Tapeworms: class cestoda • Free Living Flatworms: class turbellaria
Planaria - Adaptations • Eyespots • Flat shape, places all cells close to surrounding water • Highly branched GVC (gastrovascular cavity)
Planaria - Response • Ganglia • Head with eyespots • Lateral flaps - function for smell • Avoid light
Planaria - Nutrition • Carnivores that prey on smaller or dead animals • Mouth extends from medial ventral side with an external pharynx • Prey digested by enzymes in GVC (extracellular digestion) • Food absorbed by cells in branches of GVC • Waste released out through mouth
Planaria - Locomotion • Move using cilia on ventral epidermis • Glide along mucus that they secrete • Some flop using muscles
Planaria - Reproduction • Asexual regeneration • Sexual • hermaphrodites (but no self fertilization)