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