CRUSTACEANS 



53 



conclude as to the alertness of their senses ? Does the cov- 

 ering of its body suggest the possession of a delicate or dull 

 sense of touch ? 



Of what motions are the eyes capable? Touch one of 

 the eyes. The result? Can a crawfish see in all direc- 

 tions ? To test this, place a crawfish on a table and try 

 whether you can move to a place where you can see the 



FIG. 81. CRAWFISH 

 (dorsal surface). 



FIG. 82. 



crawfish without seeing its eyes. What are the advantages 

 and disadvantages of having the eyes on stalks ? 



Touch the body and the several appendages of the 

 crawfish. Where does it seem most sensitive to touch ? 

 Which can reach farther, the antennae or the big claws ? 

 Why are short feelers needed as well as long ones ? 



Make a loud and sudden noise without jarring the craw- 

 fish. Is it affected by sound? 



External Anatomy (Figs. 81, 82, 83, 84). Is the body of 

 the crawfish rounded out (convex) everywhere, or is any 

 part of its surface either fiat or rounded in (concave) ? 



