Notes on Mollusca Classes - Class POLYPLACOPHORA(Chitons 1...

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Class POLYPLACOPHORA (Chitons) 1. Metameric body plan 2. Flattened oval body with 8-plate shell 3. Radula functions as scraping organ to harvest algae from rock Class Gastropoda (sea slugs, snails) 1. ~40,000 species 2. marine or terrestrial 3. Single shell that can be coiled or spiral 4. Radula used for rock grazing 5. Marine species possess gills 6. Terrestrial species utilize mantle cavity as lungs 7. Torsion: mantle cavity and anal opening move from posterior to anterior. Torsion occurs during development as one of the lateral muscles grows faster than on the other side. 8. Torsion matters for predators (their mouths are designed for a specific torsion) 9. Digestive tract- follows from mouth up through mantle and curves back down. Class BIVALVIA (clams, scallops, mussels, oysters) 1. ~950,000 marine and 500 freshwater species.
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Unformatted text preview: 2. Equipped w/ two shells hinged dorsally and pulled together with adductor muscles. 3. Head and radula reduced 4. Filter Feeding through specialized appendages (palps) and gills 5. External Morphology pg. 18 6. Anatomy of visceral mass pg. 19 7. Circulatory system pg. 19 8. Locomotion, foot extends through soil to propel forward, pg. 20 • • Class CEPHALOPODA: squids, octopus 1. ~600 marine species 2. 2 subclasses: Nautiloidea (shell retained) and Coleoidea (shell reduced) 3. Foot modified to tentacles 4. Anterior tentacles modified to pincer fangs in mouth regions 5. Locomotion by walking or jet propulsion 6. Exceptionally well developed visual organs 7. Octopus can change body coloration Coleoidea- 2 tentacles, 8 arms 1. Study anatomy on pg. 23...
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  • Spring '10
  • Kant
  • mantle cavity, Coleoidea, visceral mass pg, External Morphology pg, Flattened oval body

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