74 A GUIDE FOR THE STUDY OF ANIMALS 



With what appendages does it grasp the food ? How is 

 the food conveyed to the mouth ? With what senses, if 

 any, does the animal test the food as it eats it ? 



3. If the crayfishes are in plenty of water and you 

 startle them in any way, some of them may swim. Watch 

 for such an occurrence and notice it carefully. How is 

 swimming accomplished .'' Which end leads in swimming ? 

 How far does the animal swim at a stroke.' How long 

 does it continue to swim.' Where does it go.' Does it 

 see where it is going.' For what purpose would this 

 method of locomotion be useful .' 



4. Place a living crayfish in a tray with water to cover 

 it, and take it to your table. Watch the crayfish as it 

 walks about in the water, then take it out and let it walk 

 out of water. Compare the two processes. What causes 

 the differences .' 



5. How many appendages are used in walking .' What 

 order, if any, is there in moving the legs .' Which method, 

 walking or swimming, does it use in going to some par- 

 ticular spot, e.£: in going to find food or cover .' Why ? 



6. Gently turn the animal on its back and watch the 

 movements of its appendages as it rights itself. Which 

 appendages does it use and how does it use them .' How 

 can it manage to use so many appendages in harmony, 

 for one result .' 



7. For what different purposes have you seen the cray- 

 fishes use their large claws .' For which does the claw 

 seem best fitted .' Can you think of any change which 

 would make it more efficient for its main purpose .' If 

 so, describe the change and tell how it would work. 



8. Test the distribution of the sense of feeling. Is it 

 anywhere especially acute .' If so, where .' Why have 

 two pairs of feelers.' Where is each pair carried when 



