32 CRUSTACEA 



I Take Preliminary Study. 

 II. Take Environment Study. 



III, Take Animal Behavior. 



IV. Take Morphophysiologic Study. 



V. Take Systematic Studies for Branch and Class. 

 VI. Mount a crayfish. 



MORPHOPHYSIOLOGIC STUDY OF THE CRAYFISH 

 A. External Morphology 



I. General Observations. 



1. Number of Segments. Zoologists claim that the crayfish 

 is composed of twenty segments. Begin with the last seg- 

 ment of the abdomen and see how many segments you can find. 

 Each pair of appendages is attached to a different segment. 



2. Length — from tip of rostrum (between the eyes) to the 

 end of last segment. 



3. Covering — the carapace. Its composition? 



4. Cervical Groove — which shows where the head and 

 thorax unite in the cephalothorax. 



