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15 Cards in this Set
- Front
- Back
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Charactersitic's of Mollusks |
~ Soft-bodied ~ Coelomates ~ Have a three part body plan ~ Most have a shell ~ Bilateral symmetry ~ Ex. Snails, oysters, clams, octopus and squid |
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Mollusks Body Plan & Organ System |
~ The three parts that make up the mollusk are the mantle, visceral mass and the foot
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Mollusk Feeding & Digestion |
~ All mollusks (Except bivalves) have a two shelled radula which is a tongue like organ covered with thousands of pointing curled teeth. ~ Food is digested in the stomach and intestine of the one way digestive tract. ~ Waste passes out the anus (Tube within a tube) |
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Animals with true coeloms |
The gut and other internal organs are suspended from the body wall and are cushioned by the fluid within the coelom. |
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Visceral Mass |
The visceral mass is the central section of the mollusk body and contains the mollsck's organs. |
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Mantle |
The heavy fold of tissue outside of the visceral mass which forms the outer layer of the body and secretes the mollusk's shell. |
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Foot |
A muscular mass found in every mollusk which is used primarily for locomotion |
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Mollusk Excretion |
~ The coelom of the mollusk collects waste body fluids ~ The cilia then pull the fluid from the coelom into a tubelike sructure called the nepheridia which recovers an useful materials (Ie. salt, sugar) ~ The remaining fluid leave via the anal pore
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Mollusk Circulation |
~ Most mollusks have a 3 chambered heart and an open circulatory system ~ Optopi and their relatives are exceptions as they have closed circulatory systems where blood remains inside of the vessels |
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Mollusk Respiration |
~ Most mollusk respire with gills found in the mantle cavity ~ Mollusk gills extract 50% or more of the dissolved oxygen from the water that passes over them ~ Most terrestrial snails have no gills and the thin membrane that lines the snail's empty mantle cavity works as a primitive lung |
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Mantle cavity |
Space located between the visceral mass and the mantle |
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Mollusk Reproduction |
~ Distinct female and male invididuals (some snails and slugs are hermaphrodites) ~ Fertilization of eggs occurs externally in most aquatic mollusks and internally in terrestrial mollusks and octopuses and their relatives. ~ The fertilized eggs develop into trochophore larave |
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Trochosphere Larave |
zx |
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Mollusk Diversity |
Gastropods, cepholopods and bivavles share the same basic organ systems and tissue layers but different feeding and body plans |
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Class Gastropoda |
~ snails and slugs that live primarily marine but some in terrestrial and freshwater ~ Most gastropods have a pair of tentacles on their heads that have eyes on their tips ~ Most have a single shell but slugs and nudibranches have no shell ~ The foot of gastropods is adapted for locomotion. In terrestrials, the base secretes mucus from the base of the foot to provide a slimy path for them to glide along ~ Many are herbivores while others are active predators |
