The document describes three classes of mollusks: Gastropoda (snails and slugs), Bivalvia (clams, mussels, oysters), and Cephalopods (octopuses, squid, cuttlefish). All mollusks have a visceral mass containing organs and a mantle cavity with gills. Gastropods have a muscular foot and radula for scraping food. Bivalves have two shells called valves held together by adductor muscles. Cephalopods are predators with advanced brains, eyes, and tentacles used to capture prey.

1. Phylum Mollusca
Class: Gastropoda
Class: Bivalvia
Class: Cephalopods

2. Class Gastropoda
Snails, Limpets and Slugs

3. Gastropoda
• Planning on being rich
and famous?
• Wining and dining at the
most expensive
restaurants?
• Romantic trips to Paris?
• Ever wonder what
Ceaser munched on
after long hard days
ruling the roman
empire?
• Than you should be
familiar with
ESCARGOT!!!!

4. General Body Plan:
Gastropod
• 1. Head foot
• Head: sensory nerves,
mouth
– Anterior: near the head/
mouth
• Foot: attachment and
locomotion
– Posterior: near the anus
– Flattened w Cilia:
locomotion

5. That slimy foot…
• Snail Slime:
– Suction power: travel up
and down trees
– Escape: Emit a nasty
tasting slime when
threatened
– Movement: Allows them
to easily squeeze
through tight spaces
– Water Retention
• How Ms. Cota looks so
young:
– Skin regenerating
– used in skin beauty
products

6. General Body Plan of
mollusks
• 2. Visceral Mass
– Organs of
digestion
– Circulation
– Reproduction
– Excretion
– Dorsal to the
head foot

7. General Body Plan:
Gastropod
• Mantle (shell)
– Attached to visceral
mass
• Encloses most of the
body
– Protection
• Mantle Cavity:
– Gas exchange
– Elimination of digestive
wastes
– Release of reproductive
products

8. Respiration
• One Gill in mantle cavity
– Oxygen is taken in
– Diffused through the cells
• Open Circulatory
System
– Pushes blood in to
expand
– Pulls it out to contract

9. General Body Plan: Mollusca
• Radula: Scraping
mouth
– Chitinous belt & curved
teeth
• Covers fleshy tongue
• Muscles move it back
and forth
• Conveyor belt
• Digestion
– Scrape algae
– Enzymes break down
food in stomach

10. CFU
• How do mollusks exchange gasses
– Filter air through their gills
• Where are these gills located?
– The mantel
• What is the structure called that scrapes up
food?
– A Radula
• All mollusks have:
– A visceral Mass
– A head foot
– A mantel

11. Reproduction
• Monoecious: can be
whatever sex they
want!
– Internal cross
fertilization
– One snail acts as
female one acts as
male
– Deposit eggs in
gelationous strings

12. Class Bivalvia
Clams, Oysters, Mussles,
Scallops

13. Bivalvia!
• Edible
• Commercial value:
Form Pearls
• Valuable in removing
bacteria from polluted
water!
– Rely on water currents to
get food
– Filter in nutrients, filter
out clean water
• Valuable food source:
humans, raccoons,
otters, birds

14. Structure
• Two halves of a shell:
Valves
– Adductor muscles hold
valves shut
• Visceral Mass
• Mantel Cavity
• Gills
• Cilia
• Siphon:
– filters water in and out of
shell

15. Foot
• Most mollusks have
foot that can be
used differently
– Attach mollusk to
surface
– Act as a lure to
attract prey
– Surround organs for
safety

16. Respiratory System
• Respiration and
digestion:
– Incurrent siphon and
gills

17. CFU
• What is the technical term for the two halves
of the shell?
– Valves
• What structure filters water in and out of the
shell
– Siphon
• What is the function of the foot
– Attach mollusk to substrate, act as lure
• Why are bivalves important to humans?
– Pearls, food source, pollution filter
• How are humans affecting bivalves?
– Over harvesting, pollution, loss of current

18. Mollusks: Cephalopods
Octopus, Squid, Cuttlefish

19. Cephalopods
• Fierce Predators
– Large brains
– Complex sensory structures
– Rapid locomotion
– Grasping tentacles
• Octopus vs. Shark

20. Locomotion
• Jet like propulsion
out of mantle
– Squid: uses it for
catching prey
• Up to 25 mph!
– Squid
catching cameras.
– Octopus: escape
method

21. Nervous/Sensory System
• Very large brain
– Dedicated to
movement/control of
tentacles
– Very smart: octopus are
known to problem solve
– Curious
• Giant Octopus
• Octopus Opening lid
• Eyes: advanced, similar to
vertebrate eyes
– Convergent evolution

22. Predator Adaptations
• Locate prey by sight
• capture prey w tentacles/
suction cups
– Tentacles reinforced w
protein
• Eat using a radula
– Cuttlefish: small
invertebrates
– Octopus:
• Nocturnal: snails, fish,
crustations

23. Predator Adaptations
• Chromatophores
– Cells that can change colors
• Tiny muscles contract or
expand and chromatophores
quickly change color
– Alarm response
– Defensive
– Blend in w environment
– Courtship
– Bioluminescence
• Cuttlefish in love