UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



ZOOLOGY 



Vol. 19, No. 1, pp. 1-83 April 4, 1919 



REACTIONS OF VARIOUS PLANKTON ANIMALS 



WITH REFERENCE TO THEIR DIURNAL 



MIGRATIONS 



CALVIN O. ESTERLY 



CONTENTS pAGE 



Introduction ' 2 



Methods and material 4 



Literature 7 



Conditions of life in the sea 14 



Experimental results 16 



Reactions of the copepods Acartia tonsa and A. clausi 16 



Phototropism 16 



Geotropism 17 



Summary ... 21 



Possible bearing of the experiments on diurnal migration 22 



Reactions of the copepod Calanus finmarchicus 22 



Phototropism 23 



Geotropism 31 



In diffuse light .....32 



In darkness 32 



In vertical light from above 32 



In vertical light from below 34 



Physiological rhythm in geotropism 37 



Summary 38 



Possible bearing of the experiments on diurnal migration 39 



Reactions of the copepod Eucalanus elongatus 41 



Phototropism 42 



Geotropism 43 



Reactions of the copepod Labidocera trispinosxnn 44 



Phototropism 45 



Geotropism 46 



In darkness and diffuse light 46 



In directive light 47 



Summary 48 



Possible bearing of the experiments on diurnal migration 48 



Reactions of the copepod Melridia lucens 50 



Phototropism 50 



Geotropism 51 



Summary 52 



Possible bearing of the experiments on diurnal migration 52 



