1. The coelom was a major development in the further advancement of animals. What did this development provide that was missing from the previous phyla? 1 point.

2. Class Polyplacophora: How do these animals manage to survive at low tide if "stuck" on a rock? What eats chitons? 1 point.

3. Class Scaphopoda: How do these organisms feed? What do they feed upon? What might feed on them? 1 point.

4. Class Gastropoda: What value have conotoxins provided to scientists? 1 point.

5. Class Gastropoda: Describe reproduction in gastropods? How does it differ from bivalves? Why do you think nudibranchs are brightly colored? 1 point.

6. Class Gastropoda: What types of relationships have nudibranches developed with cnidarians? Describe. 1 point.

7. Class Bivalvia: Describe the physiology involved with the use of the muscular foot by a bivalve for locomotion. 1 point.

8. Class Bivalvia: Where is the zebra mussel endemic? Why has the zebra mussel become such a threat to humans? What are scientists doing to combat the zebra mussel? 2 points.

9. Class Cephalopoda: How was the buoyancy problem solved by externally shelled cephalopods? Describe the method of respiration in the Nautilus and how this method differs from other cephalopods. How do the tentacles differ in the various cephalopods? Osmosis is a process used by the Nautilus to adjust for pressure differences. How does this mechanism function and what is the significance to the Nautilus? 4 points.

10. Refer to page 346, figure 17-41 to answer the following questions.
A. What does the thickness of the brown lines for each of the classes represent?
B. What reason could be given for the Class Scaphopoda's line branching from the Class Bivalvia's line?
C. What body form does it appear that all molluscs are derived from and what Class does it resemble?
D. What relevance, if any, does the quote from Yochelsen (pg. 346) regarding molluscs fossils have? 1 point.

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