Marine Ecology, April 9, 2007 Invertebrates 2: Phylum Mollusca
Phylum Mollusca: The “soft-bodied” animals
Molluscan body plan Hypothetical ancestral mollusc (HAM) Shell Mantle Mantle cavity Ctenidia Visceral mass Head and assocated sensory structures Radula Foot and epipodial tentacles
Class Polyplacophora: chitons “many plates” Differences from HAM 8 shell plates Mantle cavity expanded around foot Multiple ctenidia Mantle grows over shell, thickened (new functions?) Reduced head without sensory structures
Phylum Mollusca Class Polyplacophora Cryptochiton stelleri
Phylum Mollusca Class Polyplacophora Katharina tunicata
Phylum Mollusca Class Polyplacophora Tonicella lineata
Phylum Mollusca Class Polyplacophora Mopalia muscosa
Phylum Mollusca, Class Gastropoda: “stomach-foot” Representative members Limpets, snails, abalones, nudibranchs Diff. from HAM Undergo torsion What is torsion? Advantages of torsion Disadvantages of torsion
Phylum Mollusca, Class Gastropoda Key: Gastropods undergo torsion!
Phylum Mollusca Class Gastropoda Diodora aspera
Phylum Mollusca Class Gastropoda Lottia gigantea
Phylum Mollusca Class Gastropoda Collisella digitalis
Phylum Mollusca Class Gastropoda Collisella pelta
Phylum Mollusca Class Gastropoda Tegula funebralis
Phylum Mollusca Class Gastropoda Littorina sp.
Phylum Mollusca Class Gastropoda Nucella sp.
Phylum Mollusca Class Gastropoda Nudibranch (dorid) Archidoris montereyensis
Phylum Mollusca Class Gastropoda Nudibranch (dorid) Rostangia pulchra
Phylum Mollusca Class Gastropoda Nudibranch (dorid) Discodoris (Dialula sandiegensis)
Phylum Mollusca Class Gastropoda Nudibranch (aeolid) Hermissenda (Phidiana) crassicornis
Class Bivalvia: “two valves” Representative members: Clams, mussels and scallops Differences from HAM Two shells Mantle/sensory structures Expanded mantle cavity Enlarged ctenidia Respiration AND feeding Reduced head Foot more elongate; Minimal area for suction
Phylum Mollusca Class Bivalvia Mytilus californianus Mytilus edulis