TWO-LAYERED ANIMALS— PHYLUM COELENTERATA 133 



REVIEW QUESTIONS 



1. How is the presence of a nervous system evident in hydra as contrasted 

 with scypha ? 



2. What advantage does hydra's method of digestion have over that of scypha? 



3. Describe reproduction in hydra. 



4. If you found a hydra in the laboratory with a forked tentacle what ex- 

 planation for its presence could you offer ? 



5. What is meant by an animal colony? 



6. How does the Portuguese man-o-war obtain its food? 



7. What is meant by the term symbiosis? Can you think of other examples 

 than that mentioned in this chapter? 



8. Explain locomotion of the jellyfish. 



9. Illustrate alternation of generations by a discussion of the life cycle of obelia. 



10. Why are animals that live in tropical waters generally more brilliantly 

 colored than those that live in temperate waters ? 



11. How does the life cycle of gonionemus differ from that of obelia? 



12. Tell how coral reefs are constructed. 



