Food Preference of Algivorous Invertebrates — Leighton 
113 
TABLE 4 
Synopsis of Preference Order Rankings 
grazing species 
Macrocystis 
Egregia 
Laminaria 
Eisenia 
Pterygophora 
Cystoseira 
Gigartina 
Aplysia 
2 
1 
6 
4 
5 
7 
3 
Astraea 
1 
3 
4 
5 
7 
6 
2 
H. corrugata 
1 
2 
4 
3 
5 
6 
7 
H. fulgens 
2 
1 
3 
4 
6 
7 
5 
H. rufescens 
1 
2 
3 
4 
6 
7 
5 
Lyt echinus 
2 
4 
3 
5 
7 
6 
1 
Norrisia 
3 
1 
2 
5 
4 
7 
6 
Pugettia 
1 
2 
4 
6 
3 
5 
7 
S. franciscanus 
1 
6 
3 
4 
5 
7 
2 
S. purpuratus 
1 
4 
2 
5 
6 
7 
3 
Taliepus 
1 
2 
3 
5 
4 
6 
7 
Total (Wt* = 0.61) 
16 
28 
37 
50 
58 
71 
48 
* Wt = Coefficient of concordance for mean preference orders of all grazing species (see text); the value is significant at 
better than the 0.1% level. 
of Macrocystis to its grazing species may help 
to explain why that alga in the field is often the 
center of grazing attack and why kelp beds hold 
the numbers and variety of grazers observed. 
ACKNOWLEDGMENTS 
The guidance and suggestions given by Dr. 
W. J. North have been invaluable to this study. 
I wish also to express sincere appreciation to 
Dr. D. L. Fox and Dr. E. W. Fager for their ad- 
vice and criticism of the methods, statistics, and 
manuscript. 
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