1. Taxonomy Kingdom Animalia Phylum Mollusca Class Class Class Class
Polyplacophora Gastropoda Bivalvia Cephalopoda
(means bearing many plates) (means stomach/foot) (means 2 shelled) (means head/foot)

2. Phylum Molluscs Mollusc = soft body
Examples: snails, slugs, octopus, clams, oysters, chiton

3. General
The second largest phylum of animals (arthropods is the largest)
Range from simple animals (clams) to very complex animals (octopus)
Have a muscular foot for movement
Have a mantle cavity which sometimes excretes a shell
Have glands that secrete mucus
Coelomates: have a true body cavity
Live in the ocean, in freshwater or on land
Most have a radula (toothed tongue) for scraping and chewing

4. Hawaiian Bobtail Squid

5. Blue Ringed Octopus

6. Giant Squid

8. Body Plan

9. Body Plan Foot: contains sensory organs and muscles for moving
Visceral Mass: contains digestive, reproductive and circulatory organs
Mantle Cavity: contains the lungs or gills and secretes the shell if there is one

10. Digestion
Digestion: highly complex and specialized to each mollusc’s diet
Radula: a toothed structure that extends out for scraping food
snail eating

13. Circulation
Circulation: open circulatory system with a heart and blood vessels

14. Nervous System
Nervous System: several of ganglia (masses of nerve cells) and nerve cords

15. Respiration
Respiration: gas exchange through either gills or lungs

16. Movement
Movement: the foot is used for moving and is specialized in each mollusc
clam moving

17. Reproduction
Sexual: Dioecious – fertilization is internal or external and eggs are laid
Asexual: hermaphrodites but do not fertilize their own eggs
Or parthenogenesis
cuttlefish mating

18. Ecological Relationship
Food source for many animal, including humans
Produce pearls (oysters)
Some are invasive species (zebra mussels, snails, slugs)
Venoms are used in neurological research

19. Class Polyplacophora Means “bearing many plates”
Found on rocky surfaces
Can roll up for protection
Most ancient species
Example: Chitons
chitons

20. Chiton

21. Chiton

22. Chiton

23. Chiton