mollusca part 1 - city college of san francisco · 2009-10-08 · mollusca part 1 polyphacophora...
TRANSCRIPT
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MOLLUSCA Part 1
PolyphacophoraScaphopodaGastropoda
Phylum Mollusca
Large group of aquatic & terrestrial invertebrates with bilateral symmetry and a body covering called the mantle, commonly with a calcareous shellMost well preserved (except slugs)Most Important group of Fossils (numbers)Organs include heart, stomach, nerve cord, musclesInferred evolution from the Hypothetical Ancestral Mollusc
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Taxonomy to know
Kingdom AnimaliaPhylum Mollusca
Class Polyplacophora- chitonsClass Scaphopoda-tusk shellsClass Gastropoda-snailsClass Bivalvia-clamsClass Cephalopoda-nautiloids
Class Polyplacophora
Shell with 8 dorsal platesHerbivores, rocky environmentsCambrian to recent
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Fossil Polyplacophora
Cambrian – disarticulated plates
Ordovician
Class Scaphopoda
Tusk shaped, hollow shell (boat foot)Sandy or silty bottom, shallow water marineOrdovician to RecentSometimes very abundant e.g. Pennsylvanian of Texas
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Class Scaphopoda
Fossil Scaphopods
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Class Gastropoda
Stomach footSnails, slugs, whelks, limpets, abaloneHead with eyes, tentacles, broad flat foot, gills or lungsTypically coiled, unchambered shell (some cap-shaped)
coiled around a columella (axial pillar)Apex, whorl, spire, lip (see p. 291)Operculum
Typically aragonite shells that disolve in acid – casts, molds, steinkernsCambrian to Recent
Class Gastropoda
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Class Gastropoda
Fossil Gastropods
Pliocene Turritella
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Fossil Gastropoda
Amphiscapha catilloides Penn. Texas
Fossil Gastropoda
Worthenia tabulataPenn. TexasGyrodes genti Cretaceous, England
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MOLLUSCA Part 2
BivalviaCephalopoda
Taxonomy to know
Kingdom AnimaliaPhylum Mollusca
Class Polyplacophora- chitonsClass Scaphopoda-tusk shellsClass Gastropoda-snailsClass Bivalvia-clamsClass Cephalopoda-nautiloids
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Class Bivalvia
Class Bivalvia aka Pelecypoda
Shell with two mirror image partsHinge with various designsNo headCambrian to recent
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Class Bivalvia
Class Bivalvia
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Class Bivalvia
Fossil Bivalves
Anadara, a bivalve with taxodontdentition from the Pliocene of
Cyprus.
an extinct bivalve from the of Wooster, Ohio (external mold).
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Class Cephalopoda
Class Cephalopoda
“Head Foot” eyes, tentacles, head well developedIntellegentStraight or coiled shell, usually planispiralOrdovician – Recent1st large group of predators
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Class Cephalopoda
Ammonites
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Fossil Cephalopod
Fossil Cephalopod