CRUSTACEANS 



223 



toms; 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 car- 

 nivorous hunters as well. The body of the crab is short and broad, 

 being flattened dorso-ventrally. The abdomen is much reduced 

 in size. Usually it is carried close to the under surface of the 

 cephalothorax ; in the female the eggs are carried under its ventral 

 surface, fastened to the rudimentary swimmerets. The young 

 crabs differ considerably in form from the adult. They undergo 

 a complete metamorphosis 

 (change of form), and their 

 method of life differs from the 

 adult. Immediatelv after 

 molting, crabs are greatly 

 desired by man as an article 

 of food. They are then known 

 as ''shedders," or soft-shelled 

 crabs. 



The fiddler crab. From photograph loaned by 

 the American Museum of Natural History. 



Other Crabs. — Other crabs seen along the New York coast are the 

 prettily colored lady crabs, often seen running along our sandy beaches at 

 low tide; the fiddler crabs, interesting because of their burrows and gre- 

 garious habits; and perhaps most interesting of all, the hermit crabs. 

 The hermit crabs use the shells of snails as homes. The abdomen is soft, 



and unprotected by a limy exoskeleton, 

 and has adapted itself to its conditions 

 by curling around in the spiral snail 

 shell, so that it has become asym- 

 metrical. These tiny crabs are great 

 fighters and wage frequent duels with 

 each other for possession of the more 

 desirable shells. They exchange their 

 borrowed shells for larger ones as growth 

 forces them from their first homes. 



The habits of these animals, and those 

 of the fiddler crabs, might be studied 

 with profit by some careful boy or girl 

 who spends a summer at the seashore 

 and has the time and inclination to 

 devote to the work. Of especial interest 

 would be a study of the food and feeding habits of the fiddler crabs. 



Hermit crab, about twice natural size. 

 From photograph loaned by the 

 American Museum of Natural 

 History. 



