CHAPTER VII 



CRUSTACEANS 



CRAWFISH 



SUGGESTIONS. In regions where crawfish are not found, a live 

 crab may be used. Locomotion and behavior may be studied by 

 providing a tub of water, or better, a large glass jar such as a 

 broad candy jar. For suggestions on study of internal structure, 

 see p. 58. 



Habitat. Do you often see crawfish, or crayfish, mov- 

 ing about, even in water where they are known to be abun- 

 dant? What does your answer suggest as to the time 

 when they are probably most active ? 



Why do you never see one building its chimney, even 

 where crawfish holes are abundant ? Is the chimney 

 always of the same color as the surface soil ? Are the 

 crawfish holes only of use for protection ? In what kind 

 of spots are crawfish holes always dug? Why? What 

 becomes of crawfish when the pond or creek dries up ? 

 How deep are the holes ? How large are the lumps of 

 mud of which the chimney is built ? How does it get 

 them out of the hole ? Why is the mud built into a chim- 

 ney instead of thrown away ? (What would happen to a 

 well with its mouth no higher than the ground ?) Why 

 are crawfish scarce in rocky regions, as New England ? 



How does the color of the crawfish compare with its 

 surroundings ? Is its color suited to life in clear or muddy 

 water ? Define protective coloration, 



5' 



