FREE SWIMMING crabs 

 like the two on this page 

 pursue an altogether dif- 

 ferent existence from that 

 of their less nimble rela- 

 tives and usually are more 

 streamlined and graceful. 

 Cronius ruber, left, comes 

 from the Galapagos Is- 

 lands. Note posterior pad- 

 dle-like legs. 



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ODD SHAPES among crabs fascinate 

 scientists but remain inexplicable. Cal- 

 linectes bellicosus, below, is a near rel- 

 ative of Callinectes sapidus, edible blue 

 crab of the Atlantic seaboard. He is a 

 prize from San Gabriel Bay, Espiritu 

 Santo Island, Gulf of California. 



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