video questions
 

MOLLUSKS:

1. Why is it inaccurate to describe mollusks as "shellfish"?
2. Which classes of mollusks are exclusively marine animals?  Which live both in  fresh water and in the sea?  Which live on land as well as in the water?  Is there  any environmental condition that is unfavorable to all mollusks?
3. With reference to examples given in the film or in textbooks, describe how  various mollusks make use of these structures: the foot, the operculum, the radula,  and the head-foot.
4. Make a list or chart showing some of the basic characteristics of mollusks.  Use  pictures or sketches to illustrate differences in external structure, reproductive  systems, locomotion, food-gathering devices, and defenses against enemies.  List  typical items in the diet of each class of mollusks and describe how the food is  obtained and eaten.
5. Explain how the snail's method of locomotion differs from that of all other  animals.  How does the scallop move?  Why does the oyster remain indefinitely in  the same place?  In what way do fish contribute to the dispersal of clams?
6. The film pointed out a resemblance between prehistoric cepholopods and their  modern descendants.  If possible, arrange to see an exhibit of fossil specimens  and compare some of the prehistoric mollusks with present-day varieties.  Do you  find any outstanding difference between comparable types?  Is there any evidence  that environmental conditions have contributed to the development of new  structures in mollusks?
7. Compare the shells of several common types of mollusks, such as the snail,  scallop, tooth shell, hard-shell clam, soft-shell clam, oyster, conch, limpet, and  chambered nautilus.  Of  what materials are the shells composed, and how were  they formed?  Describe the structural differences between bivalves and univalves.   How do you account for the distinctive variations in shape and coloring?
8. For what special purposes, other than protection, do he mollusks use these  shells? Read about and report on the life cycle of one species of mollusk.  If  possible, examine a live specimen in class.
9. Describe the structures and abilities that make cephalopods the most highly  developed of all mollusks.  In what ways do they exercise greater control over  their environment?  What does the nautilus have in common with the squid and  octopus?
10. By consulting a chart or a biology textbook, review the classification of animals.   How do mollusks rank in complexity of structure with the other invertebrates?  In  what important ways do they differ from the amoeba, which is the simplest type  of invertebrate, and from the insect, which is the most complex?
11. Name some of the products derived from mollusks and discuss the contributions  they make to man's industries and pleasures.