Phylum Mollusca
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Transcript of Phylum Mollusca
Class Scaphopoda & Cephalopoda1
Phylum Mollusca
Class Scaphopoda
Class Cephalopoda
Class Scaphopoda & Cephalopoda2
Class Scaphopoda
Defining characteristics– 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 & Cephalopoda3
Class Scaphopoda
Commonly called tooth shells or tusk shells
Have lost ctenida along with ability to filter feed
Never spirally wound but grows linearly
Class Scaphopoda & Cephalopoda5
Class Cephalopoda
Defining characteristics– 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 & Cephalopoda6
Cephalopod Characteristics
The most highly organized of all the molluscs, the foot is closely associated with the head
Can be as large as 1,000kg. and 18m.– Architeuthis spp.
Class Scaphopoda & Cephalopoda7
Defensive Mechanisms
Since they are susceptible to predation they have evolved chromatophores
An ink sac that is associated with the digestive system and discharged out the anus
Class Scaphopoda & Cephalopoda8
Sensory & Nervous System
Eyes– All but the nautilus have
image forming eyes that are like mammals
Convergent evolution
Class Scaphopoda & Cephalopoda9
Reproduction
Sexes are separate– Males have one modified
arm (hectocotylus) for sperm transfer
Sperm are enclosed in packets called spermatophores
Class Scaphopoda & Cephalopoda10
Squid
10 sucker bearing arms surround the mouth– 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 & Cephalopoda11
Squid Internal Anatomy
Class Scaphopoda & Cephalopoda12
Squid Locomotion
The foot forms the funnel The upper end of the mantle
is extended into a pair of triangular fins
– Can move very quickly 5-10 m/s
Class Scaphopoda & Cephalopoda13
Octopus
Have 8 arms all equal in length– 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 & Cephalopoda14
Learning and Memory
Benthic feeders on bivalves, crabs and fishes
Amazing ability to learn quickly and remember for several weeks
Class Scaphopoda & Cephalopoda15
Could an Octopus be your next Professor?