1. Phylum Mollusca
Fig. 16.CO

2. Phylum Mollusca Protostomes Lophotrochozoan group
Eucoelomates (coelomates)
Tridacna gigas
Tridacna squamosa

3. Phylum Mollusca Soft Bodied Shelled Cephalization Body Divisions
Some without
Cephalization
Sensory organs
Mouths
Body Divisions
Visceral Mass
Head-Foot
Mantle
Fig. 16.1a
Tonicella lineata

4. Phylum Mollusca Complete digestive tract Digestive glands
Octopus briareus
Complete digestive tract
Digestive glands
Specialized feeding structures
Circulatory system
Heart (2 chambers)
Open system in most groups
Closed in cephalopods
Coelom restricted to pericardium in most cases

5. Phylum Mollusca Advanced nervous system Excretory system Reproduction
Brain
Sensory organs
Eyes (simple and camera)
Sensory papillae
Excretory system
Kidney-like nephridia
Reproduction
Monoecious and dioecious
External development
External & internal fertilization

6. Mollusc Phylogeny Mantle secreting shell Muscular foot Chambered heart
Fig

7. Mollusc Taxonomy Polyplacophora Major classes Chitons
Chiton tuberculatus lives in the rocky intertidal zones eat algae with its radula
8 shell plates
Major classes
Polyplacophora
Chitons

8. Mollusc Taxonomy Gastropoda Major classes Subclasses: Prosobranchia
Atlantic triton’s trumpet (Charonia variegata)
Major classes
Polyplacophora
Gastropoda
Subclasses:
Prosobranchia
Shelled marine gastropods
Tiger cowrie (Cypraea tigris)

9. Mollusc Taxonomy Gastropoda Major classes Subclasses: Opisthobranchia
Spotted sea hare (Aplysia dactylomela)
Major classes
Polyplacophora
Gastropoda
Subclasses:
Prosobranchia
Opisthobranchia
Sea slugs (marine)
Phidiana hiltoni
zebra sea goddess (Hypselodoris zebra)

10. Mollusc Taxonomy Gastropoda Major classes Subclasses: Pulmonata
Helminthoglypta walkeriana
Major classes
Polyplacophora
Gastropoda
Subclasses:
Prosobranchia
Opisthobranchia
Pulmonata
Terrestrial snails/slugs
Freshwater snails
Giant banana slug (Ariolimax columbians)

11. Mollusc Taxonomy Bivalvia Major classes Polyplacophora Gastropoda
Bay scallop (Aequipecten irradians)
Major classes
Polyplacophora
Gastropoda
Bivalvia
Clams, oysters, mussels, scallops
Edible mussels (Mytilus edulis)
Ostrea edulis

12. Mollusc Taxonomy Major classes Cephalopoda Polyplacophora Gastropoda
Giant cuttlefish (Sepia latimanus)
Major classes
Polyplacophora
Gastropoda
Bivalvia
Cephalopoda
Octopus, squid, nautilus
Octopus sp
Nautilus sp

13. Generalized Mollusc Anatomy
Fig. 16.2

14. Gastropod Feeding Apparatus
Fig. 16.3

15. Respiration: Gills
Fig. 16.4

16. Shell Structure & Formation
Fig. 16.5a

17. A Pearl Among the Swine
Fig. 16.5b

18. Mollusc Reproduction & Development
Indirect development
Larval stages
Trochophore larva
Free swimming, ciliated, shell formation begins
Veliger larva
Free swimming, ciliated velium forms,
Shell/body torsion occurs
Spat
Metamorphic form between veliger and juvenile
Shell elaborates

19. Trochophore Larva
Fig. 16.6

20. Gastropod Veliger Larva
Mouth
Velia
Fig. 16.7
Shell

22. Veliger
Zygote
Trochophore
Juvenile
Spat
Adult

23. Adult Abalone
Fig a

24. Class Gastropoda
The Shell Game
Fig

25. Class Gastropoda - Torsion
Fig

26. Gastropod Shell Coiling
Fig

27. Generalized Gastropod Anatomy
Fig

28. Marine Gastropods
Cowries
Fig b

29. Marine Gastropods
Sea Hare – Aplysia sp
Fig

30. Marine Gastropods - Nudibranch
Fig

31. Terrestrial Gastropods - Pulmonata
The mantle cavity serves as a “lung”
Glandular epidermis
Secrete mucus (slime) upon which gastropod glides
Fig a

32. Terrestrial Gastropod - Pulmonata
Pneumostome
Fig b
Slugs lack shells
Mantle thickened
Pneumostome
Air intake into mantle cavity

33. Phylum Mollusca, Class Bilvalia
Two shells
Incurrent & excurrent siphons
No cephalization
Fig

34. Generalized Bivalve Anatomy
Fig

35. Bivalve Anatomy (Sagittal)
Fig b

36. Bivalves are Typically Filter Feeders
Fig a

37. Bivalve Life Cycle
Fig

38. Glochidia – Unique Larval Stage of Freshwater Bivalves
Internal fertilization
Early development in brood chamber (region of mantle cavity)
Release of glochidia veliger larvae
Glochidia attach to gills of fish and are distributed
Fig a

39. Phylum Mollusca, Class Cephalopoda
Closed circulatory system
Shell: lost in Octopus, extremely reduced and enclosed in mantle in squid, planar spiral in Nautilus
Cephalization
eye
Beak around mouth
Tentacles/arms
Fig

40. Cephalopod Anatomy
Fig a

41. Squid are the largest Cephalopods

42. Cephalopod Eye
Fig

43. Mating
Fig

44. Direct Development in Cephalopods

45. Color & Morphology Changes for Camouflage