THE BEHAVIOR OF A PARASITIC COPEPOD, 

 LERNAEOPODA EDWARDSII OLSSON 



NATHAN FASTEN 



Zoological Laboratory, The University of Wisconsin 



CONTENTS Page 



I. General Remarks 36 



II. Description of the free-swimming Copepod 36 



III. Hatching the organism 40 



IV. Movements of the larvae under normal conditions 42 



V. Reactions to contact 45 



VI. Reactions to gravity 45 



VII. Reactions to light r . . . 46 



1. Behavior in daylight. 



2. Behavior in artificial light. 



3. Behavior in light of low intensity. 



VIII. Reaction to heat 51 



IX. Reactions to chemicals 51 



X. Infection experiments 55 



XI. Conclusions 58 



XII. Summary 59 



XIII. Bibliography 60 



I. GENERAL REMARKS 



The data presented in this paper were obtained during July 

 and August of 191 2, while the author was in the service of the 

 Wisconsin Fish Commission, studying an outbreak of parasitic 

 copepods in the trout hatchery at Wild Rose, Wis. The brook 

 trout, Salvelinus fontinalis, were found to be attacked by the 

 copepod Lernaeopoda edwardsii. Most generally this parasite 

 attaches itself to the filaments of the gills, but sometimes it is 

 found on the gill operculum, the roof of the mouth, and on the 

 pectoral and pelvic fins. For its identification, I am indebted 

 to Professor C. B. Wilson. To the Commissioners of Fisheries 

 of the State of Wisconsin, and their employes, especially Mr. 

 Zalsman, foreman of the Wild Rose hatchery, my thanks are 

 due for many courtesies shown me. To Professors E. A. Birge, 

 George Wagner, and A. S. Pearse I wish to extend my best 

 thanks for their many helpful suggestions. 



II. DESCRIPTION OF THE FREE-SWIMMING COPOPOD 



Lernaeopoda edwardsii, like all known species of the Lernae- 

 opodidae, is parasitic during almost its whole life. The dura- 



36 



