Fig. 11-5. The common crayfish (Cambarus) found over most of the United States. They live in ponds and streams 

 where they feed on small fish or any other animal, dead or alive. Note the great area of the expanded tail 

 (oropods and telson). This is very effective in locomotion. When disturbed, the animal contracts its tail power- 

 fully, thus sending it darting backwards. The crayfish is much like its marine cousin, the lobster. 



A B 



Fig n-6. The large edible blue crab of the Atlantic Coast (Ca//.nectes). A. This crab is agile even on the sandy 

 beach. It is moving rapidly toward the ocean in its typical side gait. When out of the water .t .s extremely pug- 

 nacious. B. Ventral view of the same animal, showing the large egg mass which is carried about until the 

 young hatch. 



