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Phylum Mollusca. Polyplacophora Gastropoda Bivalvia Scaphopoda Cephalopoda. Molluscs. Have adapted to a wide variety of habitats Terrestrial, marine, benthic, and accomplished swimmers. The Molluscan Body Plan. The body plan is similar and distinct from all other phyla
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Phylum Mollusca Polyplacophora Gastropoda Bivalvia Scaphopoda Cephalopoda Phylum Mollusca
Molluscs • Have adapted to a wide variety of habitats • Terrestrial, marine, benthic, and accomplished swimmers. Phylum Mollusca
The Molluscan Body Plan • The body plan is similar and distinct from all other phyla • The Mollusca body plan includes: • A large muscular foot • A radula • Mantle and mantle cavity • Usually a small head • Soft unsegmented body • A hard non-living calcareous shell Phylum Mollusca
The Foot Phylum Mollusca
The Radula • Radula • Some molluscs have a rod of digestive enzymes (crystalline style) in the stomach Phylum Mollusca
The Mantle • The mantle is the body wall that enclose the body cavity Phylum Mollusca
The Mantle Cavity • Houses the viscera and comb-like molluscan gills • Ctenidia are respiratory in function and can collect food particles • Mantle cavity also is the site for reproductive, excretory, and digestive systems Phylum Mollusca
Taxonomic Summary • Phylum Mollusca • Class Polyplacophora • Class Gastropoda • Subclass Prosobranchia • Subclass Opisthobranchia • Class Bivalvia • Class Scaphopoda • Class Cephalopoda Phylum Mollusca
Class Polyplacophora • Defining characteristics • Shell forms as a series of 7 to 8 separate plates • Chitons Phylum Mollusca
Chiton Lifestyles • Found close to shore mainly in the intertidal where they live on hard substrates Phylum Mollusca
Chiton Anatomy Phylum Mollusca
Ingestion and Digestion • Radula is used to scrape algae from the rocks • Mouth is anterior and anus is posterior; linear digestive tract Phylum Mollusca
Reproduction • Reproduction • Sexes are separate with fertilization occurring in the water column • Trochophore larvae • Free swimming which settles and metamorphoses into an adult Phylum Mollusca
Local Representative • Eastern Beaded Chiton (Chaetopleura apiculata) • Occurs subtidally on old shells Phylum Mollusca