396 QUESTIONS, PROBLEMS, AND SUGGESTIONS 



10. Dominance. — Are sponges a dominant branch of animals? Where 

 most abundant? (p. 15). Where least abundant? Why? 



11. Dispersal. — Name means and manner of dispersal. 



12. Barriers. — Name principal environmental barriers and state why 

 barriers. 



CCELENTERATA 



1. Body Plan. — A two- layered, sac-like body with hollow tentacles, 

 e. g., the hydra (p. 18). 



2. Symmetry. — See 2 under Protozoa. 



Significance of this symmetry to the locomotion of the co^lenterates? 



3. What are the means and manner of nutrition, reproduction, locomo- 

 tion, behavior, defense, and dispersal? 



4. Name the most important of the eight factors or forces in the three- 

 fold struggle for existence and the fivefold environment of this branch. 



5. What are the variations in the body plan (appendages included), 

 body nutrition, reproduction, dispersal, barriers, food, and economic use 

 or value of the four classes of this branch? 



6. Note increasing complexity of the animals of this branch over 

 sponges in body plan. 



7. Behavior or Mind (p. 8). — Manifestations of? Advance over 

 sponges? 



8. Alternation of Generations. — Give a brief account of it in the classes 

 of this branch. 



9. Specialization, differentiation, or division of labor in this branch. 

 Comment on, as seen in Figs. 15, 16, 18, 21. 



10. What do the following terms mean, as used in tliis branch: colony; 

 medusa, zooids? 



11. Compare the hydra (Fig. 10) and Physalia (Fig. 16); hydra and 

 coral-polyp; hydra and sponge; and hydra and ameba, as to body plan, 

 nutrition, multipUcation, defense, and animal behavior. (See Lab. Guide, 

 pp. 12-14.) 



12. Primitive or Generalized Form. — From what generalized or primitive 

 form do you consider that the four present classes of this branch originated? 



13. Phosphorescent Forms. — What classes of this branch furnish phos- 

 phorescent animals? What is the function of the phosphorescence? 



14. Economic value to man (p. 32). 



15. What are the special body structures that interest you in the forms 

 illustrated in Figs. 10 to 21? 



16. Increasing Complexity. — In what body structures or behavior 

 (mind) manifestations have the ccelenterates increased in complexity 

 over the sponges? 



17. How would you summarize the coelenterates? 



