DIURNAL MIGRATION OF PLANKTON CRUSTACEANS* 



Edward R. Baylor and Frederick E. Smith 

 University of Michigan 



The behavior exhibited by certain freshwater and marine plankton in 

 response to changes of single parameters of the environment, such as 

 polarization, wave length or intensity of radiation, temperature, pressure, 

 pH and redox potentials, are of increasing interest because they can be 

 systematized and subjected to physiological analysis. In general the be- 

 havior in response to these parameters appears to be concerned with 

 vertical migration or obtaining food. What effect, if any, these parameters 

 may have on other behavior patterns is beyond the scope of our present 

 efforts. 



The experiments to be described have been performed by the authors 

 and William E. Hazen with the help of students and colleagues. Our re- 

 search strategy consisted of two stages of attack. In the first stage, we con- 

 centrated our efforts entirely on those qualitative observations which we 

 felt would delineate the general behavior mechanisms under study. Thus 

 we postponed the development of quantitative techniques, the second stage 

 of the attack, until we had completed some preliminary analyses of a num- 

 ber of the behavior-pattern mechanisms. The quantitative techniques now 

 under development are particularly important for either elegance of de- 

 scription or accuracy of analysis, since many behavior patterns of zoo- 

 plankters are actually the end result of algebraic addition of many appar- 

 ently random locomotion vectors and velocities, such as appear in ortho- 

 kinesis, klinokinesis (Fraenkel and Gunn, 1938), or color dances (Smith 

 and Baylor, 1953). The qualitative results reported here may in all cases 

 be quantified to the following extent — that more than 75% of the popula- 

 tion (never less than 100 individuals unless otherwise specified) must 

 execute the same behavior pattern at the same time in response to the 

 stimulus. The present paper is a summary of certain of our qualitative 

 observations. 



Rather than survey what many animals do in many diverse situations 

 we thought it better to attempt a synthesis of what one animal does in 

 many situations. This tentative synthesis is complex ; for the moment its 

 purpose is to serve as an object of criticism by this audience as a guide to 

 more fruitful experiments. We are not at all sure that our interpretations 



* This study was supported in part through a grant from the Office of Naval Re- 

 search. Contract No. NONR 1224(05). 



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