Transcript Phylum Mollusca

Phylum Mollusca
Class Scaphopoda
Class Cephalopoda
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Class Scaphopoda & Cephalopoda
Class Scaphopoda
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Defining characteristics
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Tusk shaped conical
shells, open at both ends
Development of anterior
thread-like adhesive
feeding tentacles
Elongated tapering
tubular shells that burrow
in sandy bottoms
Class Scaphopoda & Cephalopoda
Class Scaphopoda
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Commonly called tooth
shells or tusk shells
Have lost ctenida along
with ability to filter feed
Never spirally wound
but grows linearly
Class Scaphopoda & Cephalopoda
Class Cephalopoda
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Defining characteristics
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Closed circulatory
system
Foot modified to form
flexible arms and
siphons
Ganglia fused to form a
large brain encased in a
cartilaginous cranium
Class Scaphopoda & Cephalopoda
Cephalopod Characteristics
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The most highly organized of all the molluscs,
the foot is closely associated with the head
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Can be as large as 1,000kg. and 18m.
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Architeuthis spp.
Class Scaphopoda & Cephalopoda
Defensive Mechanisms
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Since they are
susceptible to predation
they have evolved
chromatophores
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An ink sac that is
associated with the
digestive system and
discharged out the anus
Class Scaphopoda & Cephalopoda
Sensory & Nervous System
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Eyes
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All but the nautilus have
image forming eyes that
are like mammals
Convergent evolution
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Class Scaphopoda & Cephalopoda
Reproduction
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Sexes are separate
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Males have one modified
arm (hectocotylus) for
sperm transfer
Sperm are enclosed in
packets called
spermatophores
Class Scaphopoda & Cephalopoda
Squid
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10 sucker bearing arms surround the mouth
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2 longer tentacular arms can shot forward and capture
prey
Form large schools and feed on crustaceans, and
fishes
The shell is reduced and lies under the mantle
Large folded gills and a circulatory system
distribute oxygen quickly
Class Scaphopoda & Cephalopoda
Squid Internal Anatomy
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Class Scaphopoda & Cephalopoda
Squid Locomotion
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The foot forms the funnel
The upper end of the mantle
is extended into a pair of
triangular fins
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Can move very quickly
 5-10 m/s
Class Scaphopoda & Cephalopoda
Octopus
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Have 8 arms all equal in length
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Rows of suckers from base to tip
Compact body with a greatly reduced shell
The body is extremely flexible and assumes a streamlined shape
when swimming with squid-like jets through the funnel
Class Scaphopoda & Cephalopoda
Learning and Memory
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Benthic feeders on
bivalves, crabs and
fishes
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Amazing ability to learn
quickly and remember
for several weeks
Class Scaphopoda & Cephalopoda
Could an Octopus be your next
Professor?
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Class Scaphopoda & Cephalopoda