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