THE ADJUSTMENT OF FLATFISHES TO VARIOUS 



BACKGROUNDS: 



A STUDY OP ADAPTIVE COLOR CHANGE ^ 

 FRANCIS B. SUMNER 



From the Naples Zoological Station and the U. S. Fisheries Laboratory, Woods 



Hole, Mass. 



THIRTEEN PLATES 



1. INTRODUCTION 



That many fishes are strikingly adapted to their surroundings 

 in respect to their general coloration is a fact famihar to all. A 

 casual inspection of any well-stocked aquarium will reveal numer- 

 ous examples. This adaptation is probably exhibited with great- 

 est constancy by the flounders and other bottom-dwelling species, 

 though some very striking examples are to be found among fishes 

 which inhabit marine algae. In the latter class, a noteworthy 

 instance is the ' sargassum fish/Pterophryne histrio (Linn.), which 

 dwells among the fronds of the 'gulf-weed' and with it occasion- 

 ally drifts to our New England shores. 



It has likewise long been known to naturalists that certain fishes 

 possess the power of changing their colors more or less rapidly 

 in conformity to variations in the color or the shade of the back- 

 ground. Those, for example, who have had much to do with the 

 common 'minnow,' Fundulus heteroclitus (Linn.), in our labora- 

 tories at Woods Hole, realize that this fish becomes far paler when 

 kept in a white vessel than when kept in a dark one. 



^ I take pleasure in acknowledging my indebtedness to the director and staff 

 of the Stazione Zoologiea at Naples, and particularly to Dr. Victor Bauer and Dr. 

 Richard Burian, for abundant facilities and valuable advice. To Columbia 

 University I owe the privilege of occupying the table maintained by that institu- 

 tion at the Naples Station. Finally, my thanks are due to the United States 

 Commissioner of Fisheries for permission to publish herewith the results of work 

 conducted at the Fisheries Laboratory at Woods Hole. 



409 



