CHAPTER XL VII 



THE ECONOMIC BIOLOGY OF INVERTEBRATES 



Vocabulary 



Polyp, the coral animal, which is not an "insect." 

 Succulent, juicy. 



Bivalves, two-shelled animals, such as clams. 

 Venomous, poisonous. 



We shall take up the economic relations of animals in the same 

 way as we have plants, giving the general uses and harm done 

 and then taking up each large animal group, somewhat in detail. 



The subject is so broad that many books have been written on 

 the economic relations of insects, birds, or mammals alone, so 

 we will be required to consult reference books for fuller information. 



Try especially to find as many examples of each case as possible, 

 particularly animals which are familiar. 



General Uses of Animals. 



1. To supply food (flesh, eggs, milk, etc.). 



2. For transportation (horse, ox, camel, dog). 



3. To provide fabric fibers (silk, wool). 



4. To provide fur (seal, mink, otter). 



5. To provide leather (cattle, sheep, horse, etc.). 



6. To provide feathers. 



7. To provide various products, such as ivory, horn, glue, 

 gelatine, hair, etc. 



8. To aid in pollenation and seed dispersal. 



9. To act as scavengers. 



10. To aid in destroying harmful animals and plants. 



Harmful Kinds of Animals. From this list it is evident that 

 man owes about as much to other animals as he does to plants. 

 There are, however, a few harmful exceptions. 



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