CHAPTER XV 

 THE CRAYFISH 



THE crayfish is a typical member of the class Crustacea of the 

 phylum Arthropoda. It is large enough for study and easily 

 obtained for laboratory use. Crayfishes inhabit fresh-water 

 lakes, ponds, and streams, and although those in one part of the 

 country may differ slightly from those in other localities, the dif- 

 ferences are of minor importance, and one description will fit 

 them all. Near the seacoast the lobster is often available for 

 study. Lobsters are larger, but in most other respects resemble 

 the crayfishes. 



Habitat. The crayfish is usually found concealed under 

 rocks or logs at the bottom of ponds and streams. Here it lies 

 with its head toward the entrance to its hiding place. When 

 crawling about or swimming in the open water, its hard shell 

 helps protect it from fish, while its color, which resembles the 

 bottom, tends to make its detection difficult. Crayfishes may 

 be captured easily by hand, with a net, or by fishing for them 

 with a string baited with a piece of meat. They thrive in an 

 aquarium, and their entire life history may be observed in the 

 laboratory. The yearly decrease in the number of lobsters 

 available for food, and the steadily increasing demand for cray- 

 fishes, will undoubtedly soon make it worth while to raise the 

 latter for market. 



Means of Protection. The crayfish is protected from its 

 enemies in several ways. The tendency to lie concealed in a 

 crevice during the day and to feed only at night protects it from 

 certain animals like the kingfisher which might otherwise find it. 



