Download I. Intro to Mollusks

Zoology
Phylum Mollusk
I. Intro to Mollusks
A. Mollusk  soft bodied
B. 2nd largest phyla
1. small  large
2. fast movers  slow movers
3. intelligent  non-intelligent
4. Deep seas  mountain tops
C. Ex: squid, clam, oyster, octopus, snail, slugs, etc.
D. Used as a food source
1. clams, oysters, etc.
E. Used for jewelry (pearls)
F. All have a “foot”  specialized muscular organ
II. Cephalopods
A. Facts
1. Cephalo = head / poda = foot
2. Includes…squid, octopus, nautilus
3. Active predators
4. shell  nautilus
5. no shell  octopus + squid
B. The Nautilus
1. Locomotion
-”foot” acts as a siphon  pushes
water out
-gas filled chambers
2. Nervous System
-intelligent
-chemoreceptor cell  used to
camouflage
3. Others
-60 to 90 tentacles (no suckers)
-sexual reproduction
-radula  tongue like structure
i. 250,000 teeth
ii. Conveyor belt
C. The Squid
1. Locomotion
-same as nautilus
2. Nervous System
-exceptional eyes
-chemoreceptor cell
3. Others
-sepia  ink sac; helps hide from
enemies
-8 arms / 2 tentacles
-pen  acts as backbone of squid
-beak – used to break up food
D. The Octopus
1. Locomotion – same as squid
2. Nervous System
-great eye sight
-extremely intelligent (can be
conditioned)
-chemoreceptor cells
3. Others
-sepia
-pen
-8 arms – all with suction cups
-beak – used to break up food
III. Gastropods
A. Facts
1. gaster = stomach / poda = foot
2. Largest group of mollusks (50,000)
3. Ex: snails and slugs
4. Dioecious (individual sexes) or
monoecious (both sexes)
5. can be terrestrial (gills or lungs)
6. Sluggish or slow moving
7. Usually feed on algae or plankton
8. Occupy a shell for protection
B. Conus
1. active predator
2. uses worm-like tongue to lure in prey
-fish bites…proboscis fires…injects
venom…paralyzes fish
3. lethal sting to humans
IV. Class Pelecypoda (Bivalves)
A. Facts
1. pelecy = hatchet / poda = foot
2. Ex: mussels, clams, scallops, oysters
3. Filter Feeders
4. no radula
5. Dioecious
B. The Clam
1. External Anatomy
a. Umbo – oldest part of the shell
b. Hinge Ligament – keeps the 2 shells
connected
c. Growth Rings
2. Umbo
3. Hinge Ligament
Anterior
Side
1. Growth Rings
Ventral Side
2. Internal Anatomy
a. Siphons
-incurrent  takes water + food into clam
-excurrent  removes waste
b. Mantle – tissue that covers the organs of the
clam
-similar to skin
c. Palp – guide food into the mouth
d. Heart
-3 chambered
-beats slow (0.2 – 30 times/min.)
e. Kidneys
-filter blood
-U shaped
-Nephridial Tubules – connect to the
kidney
f. Ganglia
-3 pairs
-poorly developed
g. Muscles
-anterior adductor
-posterior adductor
-both close the shell
-Extremely strong