Download Mollusks Marine Biology Lindsey Maddox and Davis Carberry

Mollusks
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Marine Biology
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Lindsey Maddox and Davis Carberry
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Phylum: Mollusca
Inside the Phylum Mollusca there are 9 different Classes.
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Aplacophora, Bivalvia, Cephalopoda, Polyplacophora, Gastropoda, Monoplacophora,
Pleistomollusca, Rostroconchia, and Scaphopoda.
Bivalvia
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One body in a shell with two hinged parts.
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Clams, oysters, mussels, scallops are just a few examples of animals in this class.
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Filter feeders that have no head.
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Gills have evolved into ctenidia.
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Specialized organs for breathing and feeding.
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Attach themselves to rocks or any other hard surfaces.
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3 part nervous system (mouth, digestive system, and foot)
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500 million years old
Cephalopoda
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Advanced nervous system- lobes with nerve cells, sensory system
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Head and foot specialized for free swimming
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Predators
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Circles of tentacles from the head
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Beak
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Closed circulatory system- rapid movement of materials
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Separate sexes
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Egg into juvenile without trochapore larvae
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Chromatosphores
Cephalopoda cont.
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Squid/Cuttlefish- 8 tentacles 2 arms, internal shells
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Octopus- 8 tentacles
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Onambered Nautiluses- retains external shell, coiled & divided into series of gas filled chambers,
soft body moves as the organisms grow, and bouyant
Gastropoda
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Largest and most diverse group
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Single shell
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Torision- larval deve. V.M. twists 180 in relation to the head
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Brings anus, gills, and mantle cavity in the front, allows adult to pull itself into the cavity when
threatened
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Move by wave like motion of foot, open circulatory system- Hemolymph- flows into hemocoel
(blood cavity)
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Separate sexes but may be hermaphroditic
Citations
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www.wikipedia.com
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Marine Science textbook