1. Mollusks and Annelids

2. Mollusks Head/Foot Visceral Mass Mantle
Sense organs, locomotion, mouth
Visceral Mass
Organ systems
Mantle
Secretes shell
Gaseous exchange (gills or lungs)

3. Basic Anatomy

4. Class Gastropoda Snails, abalone, slugs, nudibranchs, limpets
Slow moving predators or herbivores
Gills in most, some have lungs
Coiling and torsion of visceral mass
Open circulatory system

5. Gastropoda Body Plan

6. Gastropoda Torsion

7. Gastropoda Coiling

8. Class Bivalvia Clams, muscles, scallops Open circulatory system
Laterally compressed
Shell in two halves, hinged
Suspension feeders
Open circulatory system

9. Bivalvia Feeding

10. Bivalvia Body Plan

11. Class Cephalopoda Octopus, squid, nautilus
Foot developed into tentacles
Very mobile predators
Highly advanced brain and eyes
Closed circulatory system

12. Nautilus Anatomy

13. Squid Anatomy

15. Cephalopod Eye
Develops from ectoderm
Convergent evolution

16. Taningia danae
Largest light producing squid - ~2 meters (7 ft)

17. Taningia danae Grips prey with rows of hooks – not suckers
Eats fish and other squid

18. Architeuthis dux
Largest invertebrate - ~18 meters (60 feet)

19. Architeuthis dux Catches prey with double row of spiny suckers
Eats fish and other squid

20. Annelids Segmented (metamers) Septa separate coelem at each segment
Longitudinal and circular muscles
Peristaltic movement
Closed circulatory system
Advanced nephridia

21. Body Plan

22. Class Polychaeta Very diverse methods of feeding Parapodia Movement
Gas exchange

27. Class Oligochaeta
Examples
Earthworms
Tubifex worms

28. Longitudinal Anatomy

29. Circulatory System Closed – capillary network for exchange
Dorsal and ventral blood vessels
Five aortic arches for pumping (heart)

30. Cross Sectional Anatomy

31. Nephridia
Found in each segment

33. Reproduction Hermaphroditic – exchange sperm Clitellum
Attach during mating
Secretes cocoon

35. Class Hirudinea Leeches Anterior and posterior sucker No septa
Coelom filled with muscle and connective tissue
Many lack enzymes for digestion – rely on bacteria