PLATYHELMINTHES!!!
Joe Wolff, Alex Miller, Nandish Desai
GERM LAYERS
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Triploblastic: Three germ layers
• Endoderm- Inner tissue layer
• Ectoderm- Outer tissue layer and nervous tissue
• Mesoderm- Muscle
SYMMETRY
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Bilateral symmetry
COELOM
•
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Acoelumate (no body cavity)
They are flat, therefore a body
cavity would not fit their function
DIGESTIVE TRACT
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No digestive tract
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Absorbs and releases nutrients across body surface
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Undigested waste is expelled through mouth
•
Tapeworms do not need a mouth, since they absorb pre-digested food
CEPHALIZATION
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Simple nervous system
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Two simple brains called ganglia and eyes
SEGMENTATION
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No segmentation
SKELETON AND APPENDAGES
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No skeleton
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Cilia and muscle layers allow movement
CIRCULATORY SYSTEM
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No circulatory organs
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Absorbs nutrients and food through diffusion and/or through a gastrovascular mouth
cavity
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http://www.youtube.com/watch?v=w0QzSYQGsnA&NR=1
RESPIRATORY SYSTEM
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No specialized organs
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Take in oxygen through diffusion
REPRODUCTION
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They split into two
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Some go through both asexual stages and sexual stages
HABITAT
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Marine, freshwater, damp terrestrial environments
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They may also live parasitically within people and animals