CONTENTS 



Page 



Abstract 1 



The problem 1 



Equipment and materials 2 



Aquaria 2 



Water 2 



Light 3 



Shell thickness meter 3 



Test animals 3 



Methods 3 



Conditioning and nneasuring 3 



Size grouping 4 



Design of experiment 5 



Effects of current 7 



Results 7 



Attacks by drills 7 



"Replacemient of food" test 7 



Tank 2 "continuation test" 15 



"Non-replacement of food" tests 15 



Duration of attacks 20 



Effect of thickness of prey's shell 21 



Discussion 22 



Acknowledgments 25 



Summary 25 



Literature cited 26 



FIGURES 



1. Close-up of dial meter, with the thickness of a Manila clam shell 



indicated by dial meter 3 



2. Measuring the length of a Japanese drill 4 



3. Design of experiments 5 



4. Arrangement of food organisms and position of each drill at time 



of release for tank 1..... 6 



5. Regression lines and scatter diagrams of duration of attack upon 



thickness of shells from Experiment I 22 



6. Regression line and scatter diagram of duration of attack upon 



thickness of all shells from Experiment I 23 



111 



