LIGHT REACTIONS OF TERRESTRIAL AMPHIPODS 



THORBORG MARIE BRUNDIN 



The University of California 



Two figures 



CONTENTS 



Page 



I. Introduction 334 



II. Habits and general description 334 



III. Phototaxis in Orchestia pugettensis 336 



IV. Phototaxis in Orchestia traskiana 338 



V. General conclusions 350 



I. INTRODUCTION 



The first work in the study of light responses of Amphipods 

 was done in the summer of 1903, by Dr. S. J. Holmes, at Wood's 

 Hole, Massachusetts. It consisted of a number of experiments 

 upon aquatic and terrestrial amphipods under various influences 

 which were designed to find some clue to the mechanism of the 

 phototactic response, and the cause of reversal in the sense of 

 phototaxis. 



The results set forth in the present paper were obtained 

 through experiments carried on along similar lines as -those of 

 Professor Holmes, with two species of terrestrial amphipods of 

 the Pacific coast. The work was carried on in the Zoological 

 Laboratory of the University of California, under the direction 

 of Professor Holmes, to whom I am indebted for many valuable 

 suggestions and kind criticisms. 



II. HABITS AND GENERAL DESCRIPTION 



Orchestia pugettensis corresponds closely in appearance and 

 habits with the Talorchestia longicornis of the east coast, which 

 was experimented on by Holmes, and described in a monograph 

 on "The Beach Flea" by Miss Smallwood. Both forms burrow 

 in the moist sand above high water mark, are of pale grayish 

 color and have long antennae. Talorchestia longicornis is strongly 

 positive to light, and specimens will quickly congregate around 

 a lantern set on the shore at night. 0. pugettensis, under normal 

 conditions, is strongly positive in the laboratory, and wquld no 

 doubt act in the same manner. 



334 



