534 MAN CONTROLS HIS ENVIRONMENT FOR WEALTH 



Several other common crustaceans used as food by man are near 

 relatives of the crayfish. Among them are the shrimp and the 

 prawn, thin-shelled, active crustaceans common along our coasts. 

 In spite of the fact that they form a large part of the food supply 

 of many marine animals, especially fish, they do not appear to be 

 decreasing in numbers. 



Another edible crustacean of considerable economic impor- 

 tance is the blue crab. Crabs are found inhabiting muddy bot- 

 toms of salt water inlets ; in such localities they are caught in great 

 numbers in nets or traps baited with decaying meat. They are, 

 indeed, among our most valuable sea scavengers, although they are 

 hunters of living prey also. The young crabs differ considerably 

 in form from the adult. They undergo a complete metamorphosis. 

 Immediately after molting or shedding of the outer shell, in order 

 to grow larger, crabs are known as " shedders," or soft-shelled 

 crabs, and are considered a great delicacy. On the western coast 

 a large deep-sea crab is caught which is an excellent article of food. 



Practical Exercise 12. List all the crustaceans you know that are found 

 in your locality. Which ones are directly or indirectly used for food ? 



Practical Exercise 13. Make a report on the lobster industry of the United 

 States. (See Readers Guide or Herrick's The American Lobster, Bui. U. S. 

 Fish Com. 1895.) 



Practical Exercise 14. If you have ever caught any kind of crustaceans, 

 describe your methods to the class. 



Fish as food. Fish are used as food the world over. The pres- 

 ent value of the yearly catch of the world is estimated at over 

 $1,000,000,000. From very early times herring were caught by 

 the Norsemen. Fresh- water fish, such as whitefish, perch, pick- 

 erel, pike, and the various members of the trout family, are 

 esteemed food and, especially in the Great Lake region, form impor- 

 tant fisheries. But by far the most important food fishes are those 

 which are taken in salt water. Here we have two types of fish- 

 eries : those where the fishes come up a river to spawn, such as the 

 salmon, sturgeon, or shad, and those where the fishes are taken on 

 their feeding grounds in the open ocean. The eggs of the sturgeon 

 are used in the manufacture of the delicacy known as caviare. 

 Herring are the world's most important catch, though not in this 

 country. The salmon of our western coast are taken to the value 



