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Phylum Mollusca!!

Phylum Mollusca!!. Created by: Mariah Ghant , Saori Ishizuka, and Monica Lin. Germ Layers. 3 germ layers Ectoderm Mesoderm Endoderm. Symmetry. Bilateral. Coelom. Mollusca are true c oelom Fluid filled cavity within the mesoderm. Digestive Tract. Extracellular digestion

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Phylum Mollusca!!

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  1. Phylum Mollusca!! Created by: Mariah Ghant, Saori Ishizuka, and Monica Lin

  2. Germ Layers • 3 germ layers • Ectoderm • Mesoderm • Endoderm

  3. Symmetry • Bilateral

  4. Coelom • Mollusca are true coelom • Fluid filled cavity within the mesoderm

  5. Digestive Tract • Extracellular digestion • Complete digestive tract • Mouth • Anus

  6. Cephalization • Evident in mollusca • Cephalopods have eyes with image formation • Neurons concentrate in a ganglial pattern

  7. Segmentation • No segmentation • Instead, body divided into head, foot and visceral mass

  8. Skeleton & Appendages • Mollusca have soft bodies • Often protected by a shell • Some have lost their shells because of evolution • Muscular tube feet • Skeleton • Shell with three layers: periostracum, prismatic layer, nacreous layer

  9. Circulatory System • Open circulatory system • Except for Cephalopods, blood does not circulate within the vessels • Collected from the gills • pumped through the heart • released directly into spaces in the tissues from which it returns to the gills and then to the heart • Closed circulatory system for cephalopods

  10. Respiratory System • Gills in aquatic forms • Discrete respiratory system • Improved capacity for oxygen uptake and distribution • Increases body mass

  11. Reproduction • Single or double set of gonads and ducts in each sex • Bivalves and some snails of mollusca are hermaphrodites

  12. Habitat • Occur in almost every habitat found on Earth • Most are found in marine environments, extending from the intertidal to the deepest oceans

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