CHANGES IN SHADE, COLOR, AND PATTERN IN FISHES, AND 

 THEIR BEARING ON THE PROBLEMS OF ADATAPTION AND 

 BEHAVIOR, WITH ESPECIAL REFERENCE TO THE FLOUNDERS 

 PARALICHTHYS AND ANCYLOPSETTA. 



By S. O. MAST. 



Contribution from the United States Fisheries Biological Station, Beaufort, N. C, and the Zoological 

 Laboratory of the Johns Hopkins University. 



INTRODUCTION. 



Color and color patterns in plants and animals have a fascinating interest for 

 almost every one. The layman as well as the artist, the scientist, and the philosopher 

 shares in this. There are not only the questions as to the origin, inheritance, and philo- 

 genetic development of such phenomenal, though relatively permanent, color schemes 

 as are found particularly prominent in many tropical birds and fishes, but also the still 

 more interesting questions regarding the biological significance and the mechanism of 

 changes in such surface characteristics in individuals; not only ontogenetic changes 

 which are more or less permanent, but especially such rapid and reversible changes as 

 are well known to occur in the chameleon and a considerable number of other widely 

 separated species. 



The literature on the subject in general is very extensive. In an excellent review 

 covering the more important references bearing only on changes in the color in animals. 

 Van Rynberk (1906) has collected a bibliography consisting of 402 titles, and since the 

 publication of this review many more papers have appeared. But in spite of all the 

 work done, it will be necessary to do much more before the more fundamental problems 

 involved are solved. 



This paper, as the title indicates, deals primarily with the reversible changes that 

 occur in the shade, the color, and the pattern in fishes, with especial reference to their 

 extent and biological significance and the factors involved in their production. Con- 

 siderable space, however, is also devoted to problems in behavior. 



That there are marked changes in the appearance of fishes has long since been 

 known. The Romans, Van Rynberk maintains, more than 2,000 years ago were wont 

 to entertain the ladies at dinner with exhibits in changes in the color in fishes, mostly 

 due to injury. In more recent times records show that under various circumstances 

 very striking changes in both pattern and color have been observed by numerous investi- 

 gators in many different fishes. These changes, in accord with their supposed cause or 

 significance, have been classified as follows: (i) Psychic, (2) sexual, (3) adaptive. 



(i) Townsend (1909) and others have observed that many fishes often suddenly 

 change in appearance, sometimes without any apparent external cause, but more often 



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