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Examples: Tubellarians, Flukes, Tapeworms. Soft, flattened worms that have tissues and an internal organ system. Simplest animal to have 3 embryonic germ layers, bilateral symmetry, and cephalization. Phylum Platyhelminthes - Flatworms. Flatworms. Flatworms. Environment
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Examples: Tubellarians, Flukes, Tapeworms Soft, flattened worms that have tissues and an internal organ system. Simplest animal to have 3 embryonic germ layers, bilateral symmetry, and cephalization. Phylum Platyhelminthes - Flatworms
Environment • Some in aquatic ecosystem • Some form parasitic relationships and infect blood or organs of host animal Food Source • Carnivores: feed on tiny aquatic animals • Scavengers: feed on recently dead animals • Parasites: feed on host organism
Maintaining Homeostasis - Internal (Circulation, Respiration, Excretion) • No circulatory system rely mostly on diffusion • No respiratory organs or heart • Have flame cells for removal of wastes Maintaining Homeostasis - External (Response) • Ganglia (group of nerve cells control the nervous system)
Movement • Cilia or muscle cells that allow them to twist and turn Reproduction • Most are hermaphrodites but must have a partner to reproduce. Some reproduce by fission (splitting in two) Evolutionary Milestone • Bilateral Symmetry
Pictures – Flatworm • Vocabulary: Coelom (683); Hermaphrodite (686) Copy this drawing Or Figure 27-3 Page 685