1. Phylum Mollusca
Lecture 10

2. General Characteristics
Bilaterally symmetry
Visceral Mass- contains organs
Mantle- secretes the shell and lines it

3. General Characteristics Con’t
Exception is cephalopods have closed circularoty system
Radula usually present (tongue)
Protostomes (_________________)

4. 3 Main Classes of Mollusca
Gastropoda
Bivalvia
Cephalopoda

6. “___________ ______________”
Gastropoda
“___________ ______________”
Snails, Slugs, Nudibranchs, Conchs, Whelks, etc.
35,000+ species

7. Freshwater, Marine, or Terrestrial
_____________________________
Move by secreting mucous with cilia or use muscular foot

8. Gastropod Anatomy

9. Torsion Protection - Shelter 180 degree rotation of visceral mass
Significance: allows the snail to retract it’s head into the shell first and it’s foot last.

11. Interesting Facts!
Land snails can lift ten times their own weight up a vertical surface (like a wall).
Largest Snail = Giant African Land Snail
Can weigh 2 pounds!

12. Gastropod Feeding
Herbivores, parasites, or predators
_______________: tongue-like organ that scrapes algae or other plant-like material

13. Radula

14. Some predatory gastropods have radula modified to pierce prey
Example: ________ __________

15. Gastropod Respiration
Gas exchange occurs in mantle cavity
______________________________________________________
___________- inhalent tube
Where water enters body

16. Gastropod Circulation
Have open circulatory system
Blood not contained w/in vessels; instead it washes over the body tissues
Blood acts as a _______________
_______________
Protection surrounding organs

17. Nervous System
Nerves concentrated into large ganglia
Most ganglia located in head region (*___________________
____________________________)
Simple or complex eyes (______

18. Nervous System Con’t
*________________________________________________________________________________
Osphradia- chemoreceptors that help to detect prey

19. Digestive System Nephridium- kidneys
______________ = primary nitrogenous waste produced in aquatic species (same as higher order)
__________________ = primary nitrogenous waste produced in terrestrial species (_______________
__________________________)

20. Reproduction Can be monoecious or dioecious
Usually exchange sperm and cross fertilize
In mantle cavity
________________________________________________________________________________________________________________

21. Snail Sex!

22. Importance
_____________________
____________________________________________

23. Class Bivalvia

24. General Characteristics
Includes clams, oysters, mussels, scallops
__________________________________________________________
Hence “Bi-valvia”

25. 30,000+ species
Clams!
Marine and Freshwater
Mostly filter feeders

26. Interesting Facts! Largest bivalve -734 pounds and 4’ long… whoa!
Ocean Quahog can live to be 220 years old!

27. Bivalve Respiration
Incurrent and Excurrent Siphons
________________________________________________________
Gills greatly expanded and cilliated (___________________________)

28. Circulatory System
Open Circulatory System
Blood not contained w/in vessels
Blood “washes” over body tissues by action of the beating heart

29. Bivalve Feeding and Digestion
_______________________________________________________________________________________
Labial palps filter out food particles
Non-edible particles flushed out through the excurrent siphon

30. Nervous System
Ganglia located in:
Esophagus
Mantle
Posterior Adductor Muscle

31. Nervous System Con’t
Most sensory organs are located in the margin of the mantle
______________________________________________________________________________

32. Reproduction
Mostly Dioecious - ____________
____________________________
Gonads located in visceral mass
Fertilization occurs in open water

33. Economic Importance
Mmm Tasty!
Pearl production
Multi-billion dollar industry

34. Class Cephalopod

35. General Characteristics
Octopus, squid, cuttlefish, and nautilus
___________________________
Have tentacles
Use jet propulsion
Closed Circulatory System

36. ______________________
Cephalopod Shell
______________________
Internal in squid (pen) and cuttlefish (cuttlebone)
Absent in octopusses

38. ________________ Use siphon for jet propulsion
Squeeze mantle cavity forcefully
Sometimes have external “wings” used to help steer

40. Feeding Active predators __________________________
Food captured by tentacles and brought to mouth
Jaws and radula used

41. Respiration & Circulation
___________________________
3 Hearts
Blood is contained w/in vessels
Respiration through gills
High metabolic rate

42. Nervous System
Very large brain
Advanced, large eyes
__________________
Chemoreceptors
Chromatophores-pigment cells

43. Some display bioluminescence: use ATP to light up
__________: brown or black ink

44. Reproduction
_____________________
Males have testes and packed sperm in spermatophores
All larval development occurs in the egg

45. Yummy food source- calamari Bait
Economic Importance
Yummy food source- calamari
Bait