MolluscII

MolluscII - MOLLUSCA II Bivalves Cephalopods Bivalves...

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MOLLUSCA II Bivalves Cephalopods
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Bivalves Shells indicative of life habit/environment – good eco indicators, Live in all marine habitats except anoxic. Invaded fresh water by mid Paleozoic. Species tend to be long-lived – little biostrat use. Ancestor (limpet-like) developed hinged shell, lost head, sense organs, radula. First appear in Cambrian Survive P/T extinction and came to dominate (due to predation & infaunal habit?) Survive K/T extinction with little effect (except rudists & inoceramids) Survive all following extinctions
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Plane of Symmetry runs between valves. Standard orientation is hinge at top. Body consists of mantle, adductor muscles, foot, gills, digestive system. No diductor muscles – use ligament as spring
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Shell interior contains muscle scars, pallial line (attachment line of mantle), pallial sinus (notch marking siphon) Also see teeth and sockets at hinge Externally beak – usually points forward prosogyral (can be opisthogyral) ligamental groove or resilifer – for ligament
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Gills used for respiration and filter feeding. Gill Types A. Protobranch – primitive B. Filibranch – W-folded gill sheets C. Eulamellibranch – folded gills with cross partitions D. Septibranch – divide mantle cavity
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Teeth and Sockets A. None B. Taxodont (Arca) C. Schizodont D. Dysodont E. Isodont F. Heterodont G. Pachydont H. Desmodont
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This note was uploaded on 10/23/2011 for the course GLY 1000 taught by Professor Parker during the Spring '11 term at FSU.

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MolluscII - MOLLUSCA II Bivalves Cephalopods Bivalves...

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