GROUPS OF ANIMALS 271 



usually invisible, and they can be studied only with 

 the aid of a microscope. 



Questions 



1. Name the five groups of vertebrates. 



2. Give examples of animals belonging to Sach 

 group of vertebrates. 



3. State the principal characteristics of each of 

 these groups. 



4. To which group of aninials does man belong ? 



5. Describe the stages through which the frog 

 passes in its development. 



6. Which class of invertebrates has the greatest 

 number of species? 



7. Which groups of invertebrates have members 

 which are of economic value to man ? 



8. Describe the development of a butterfly. 



9. From what animal are pearls obtained? 



10. To which group do the simplest animals belong ? 



