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Specific characters
• System level of organization
• Triploblastica
• Coelomate
• Bilateral symmetry
• The body is soft covered with mantle
which secrets calcareous shell.
• The body is divided into head foot and
visceral mass.
•The mouth contains an important organ
called radula which is the device of feeding.
Mollusca
Class:
polyplacophora
Class:
bivalvia
Class:
gastropoda
Class:
Cephalopoda
According to:
Type of shell
polyplacophora
monoplacophora
bivalvia
gastropoda
cephalopoda
Class: Polyplacophora
Ex:Chiton sp.
• . All are marine and live on rocks in
shallow water.
• The shell with several plates reaches
8 overlapped plates
• The head is reduced and there are no
eyes or tentacles.
Class: Bivalvia
Ex1: Anodonta sp.
•They are laterally compressed
and possess bivalve shell
•The head is reduced and there
are no eyes or tentacles
•They are filter feeder, where
they filter food particles from
the water current that inter the
shell through the inhalant
siphons
Growth lines
umbo
- Class: Gastropoda
Helix sp. (desert snail)
•The body is formed from head foot
and visceral mass
•The head and foot not distinct
Class: Cephalopoda
•-The shell is internal
•The head carry well developed eyes
•Foot represented by funnel and arms
•- They defend themselves
by excreting ink ( ink sac)
Order:Dibranchiata
Pair of gills
shell may be present or not
Suborder
Decapoda
Suborder
Octapoda
web
suborder :Octapoda
Ex: Octopus sp
• 8 arms all equal and each
arm with 2 rows of sessile
suckers
•No shell
suborder: Decapoda
Ex: Sepia sp
• 10
arms unequal and each arm
with 4 rows of stalked suckers.
•With internal shell.
eyes
Lateral fin