AIM: Describe the main characteristics of mollusks and
explain how we can distinguish between gastropods,
bivalves and cephalopods?
OBJ: Given notes and activity sheet SWBAT describe the
main characteristics of mollusks and explain how we can
distinguish between gastropods, bivalves and cephalopods
with 70% accuracy
DN: HW check- Worms Activity Sheet; Complete & hand-in
Worms Quiz (Test#: WLQ, Q:1-16, Full Name).
ACT: Introduction to Mollusks (notes)
Text, read p. 40-45, Complete Mollusks Activity Sheet
HW: Complete Mollusks Activity Sheet; Study for Interim
Exam, Nov 6; Invertebrate Exam, Nov 12.
Mollusk Characteristics
soft (unsegmented) body
hard outer shell
mantle (covering internal organs)
foot
open circulatory system
Example: clams, oysters, scallops, snails,
mussels, squid, octopus, cuttlefish
___________________________________
3 groups: gastropods, bivalves & cephalopods
Gastropods
1] radula (ribbon of tiny teeth)
2] creeping foot moves on
slippery mucus
Gastropods
(Snail, Slug)
Bivalves: two-shelled Mollusk
two shells
filter feeders
Bivalves
(clams, scallops, oysters, mussels)
Cephalopods (squid, cuttlefish, nautilus, octopus)
tentacles (modified foot)
swim by jet propulsion
with/without shell
nautilus: shell
squid/cuttlefish: tiny shell inside body
octopus: no shell
closed circulatory system
complex nervous system
large brain: intelligent
Cephalopods
(Squids & Octopuses)
Nautilus: A living Fossil
Fossil goniatites & ammonites:
ancestors of the Nautilus