34 COPEIA 



jaws of the two touched. His mouth was a bit larger 

 or wider open so that his jaws overlapped for an in- 

 stant those of the other fish. They then separated. 



During the whole of this manoeuvre the two fish 

 faced each other. To each the vivid red mouth lining 

 of the other must be visible. To the human observer 

 it is startlingly conspicuous. He cannot escape the 

 impression that the fish are making a display; he 

 might be pardoned for saying that they are bluffing. 

 This impression is strengthened by the wide gaping 

 of the mouth, by the facing position and by the rather 

 deliberate approach. It is as if each were expecting 

 the other to flee at any moment. 



Such displays of conspicuous color patches are 

 not rare among inconspicuous insects. They are 

 thought to have been. developed through natural se- 

 lection and to serve the purpose of startling an enemy 

 (Schreckfarben). In conspicuously colored insects 

 they are probably quite as common, but are over- 

 looked because superimposed on an already conspicu- 

 ous coloration. In the grunt, the red mouth patch 

 displayed suddenly on a background of yellow and 

 blue stripes is to man conspicuous and startling. If 

 seen in an insect it would undoubtedly be classified as 

 a "Schreckfarbe." How it affects the fish's natural 

 enemies we can hardly know. 



The color patch is revealed to its fullest extent 

 when the mouth is opened wide in the presence of an 

 enemy. It seems to be little exposed in the usual tak- 

 ing of food. I have never seen it then. But the food 

 of the species consists of crustaceans and annelids, 

 whose visual organs, so far as we know, are unaf- 

 fected by any color display- Selection need then 

 hardly deprive the Haemulons of their mouth patches 

 in order to assure their food supply. Considered 

 as a contrivance for bluffing enemies the mouth 

 patch seems of doubtful advantage. It is to be ex- 

 pected that enemies, if affected by it, would soon 

 become accustomed to it and be no longer startled. 



