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Phylum - Mollusca
- 1. Bilaterally symmetrical , coelomates
- 2. Open circulatory system (hemoceol) - well develped heart
- 3. Complete digestive tract
- 4. Mantle that secretes calcareous shell plates or shells
- 5. Inmany species well-developed muscular foot
- 6. Mouth or buccal region in manyspecies with radula
- 7. Well-developed nephridia "kidneys"
- 8. Trochophore larva (expecially in marine forms), most dioecious
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Phylum - Mollusca
class - Bivalvia (=Pelecypoda)
- 1. Clams,scallops, oysters
- 2. 15,000+ species
- 3. Two-valved molluscs
- 4. Shell produced by mantle
- 5. Filter feeders (suspension feed)
- 6. No radula
- 7. Stong gills (=Ctenidia)
- 8. Dioecious
- - Verysuccessful class
- - Ctenidia are specific to this group.
- - Filter feeders take in small particles while suspension feeders make use of net or catching devise to bring in food
- - Have an open circulatory system with a heart
- - Glochidium - larvae of freashwater clams
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Ctenidia are specific to which group?
- Phylum - Mollusca
- Class - Bivalvia (=Pelecypoda)
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Filter feeders....
- Take in small particles
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Suspension feeders....
- make use of net or catching devise to bring in food
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Glochidium....
- Larvae of freshwater clams
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Ctenidia...
- Strong gills (Class Bivalvia)
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Phylum - Mollusca
Class - Cephalopoda
- 1. Octopods, swuids, cuttlefishes,nautius
- 2. 650 spps. -7,500 fossil forms described
- 3. Cephalizaion
- 4. Shell reduced - cuttlefish
- 5. Possession of chromatophores (pigment cells which give ability to change color)
- 6. Jaws or beak - ink scs in some species
- 7. Dioecious
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Chromatophores....
- pigment cells which give ability to change color (Class - Cephalopoda)
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Phylum - Mollusca
Class - Polyplacophora
- 1. Chitons - 600+ speies - all marine
- 2. Broad large ventral foot
- 3. Dorsal surface armed with articulating plates made up of Calcium carbonate (usually 8 plates)
- 4. Very strong rasping radula
- 5. Mostly intertidal ingabiting rocky shores
- 6. Dioecious
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Dorsal surface armed with articulating plates made up of Calcium carbonate (usually 8 plates) is a characteristic of which class?
Class - Polyplacophora
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Phylum - Mollusca
Class - Gastropoda
- 1. Snails, slugs, nudibranchs (sea slugs)
- 2. 35,000+ spp. extant - over 15,000 described fossils
- 3. Marine, freshwater, and tereestrial forms
- 4. torsion - 180 degree shift in body mass
- 5. Detorsion - good example nudibranchs
- 6. Many species carry a shell (snails)
- 7. Strong radula
- 8. Dioecious and Monoecious
- - torsion - the spiraling of the body (ex. to make it more fit for a shell)
- - detorsion - the straighteding out of the body in adulthood.
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Torsion...
- -180 degree shift in body mass
- - the spiraling of the body (ex. to make it more fit for a shell)
- - characteristic of the Class - Gastropoda
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Detorsion....
- - the straightening out of the body in adulthood
- - good example nudibranchs
- - Characteristic of the Class - Gastropoda
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Phylum - Mollusca
Class - Monoplacophora
- 1. Simple single shell (cap-like)
- 2. "Living Fossils" - rediscovered in 1952 on the coast of Chili in very deep waters.
- 3. Neopoline - living Genus discovered - now several species have been discribed (11+)
- 4. Major significance - presence of segmentation - eveolutionary relationships possibly with the Annelids
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What class is an example of a "living Fossils" ?
Class - Monoplacophora
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