Adjustment of the Gray Snapper to Its Food. 303 



of Abudefduf. Its broad contrasting stripes render it conspicuous. When 

 in its natural position, attaclied to the body of a shark by the sucker on the 

 top of its head, it is not molested by the snappers. An individual 6 inches 

 long was thrown from the dock and at once taken by the snappers. Its 

 coloration gave it no protection. Just as the snappers treat Abudefduf and 

 Elacatinus as accessible when not close to a massive coral or large hard sur- 

 face, so they treat Leptechineis as accessible when detached from its host. 



The wholly unfamiliar bright red salamander Diemyctylus viridescens'^ 

 was taken with no trace of hesitation, and thus is illustrated again the failure 

 of a warning color to afford protection. 



The results of the feeding experiments may be brief!}' summarized as fol- 

 lows : 



Gra\ snappers attempted to capture all the 22 species of fish and i 

 amphibian thrown to them. They actually took all the species but one 

 {Chcrtodon ocellatus), which escaped on account of its large size and 

 defensive armor. No hesitation zvas shozvii in seising any of the fish offered, 

 except in the case of the larger individuals of Chylomycterus schapfi, 

 which are formidable by reason of their erratic movements, power of infla- 

 tion, and defensive spines, and are probably netv to most of the snappers. 

 The species taken zvere of a variety of colors and color patterns and were 

 nearly all conspicuous. They included the colors and patterns considered as 

 typically warning. In Angelichthys, Chtctodon, Chylomycterus, Hcpatus, 

 and Pomacanthus conspicuousness is combined zvitli unpleasant attributes in 

 the form of defensive spines, the typical zvarning combination, yet these fish 

 were all instantly taken. 



Individuals of certain species escaped from the pursuing snappers, (a) 

 because of inconspicuousncss combined with speed (Caran.v crysos) ; (b) 

 because of erratic movement combined with potver of inflation, size, and 

 defensiz'e spines {Chylomycterus schocpfi) ; (c) because of erratic flight 

 to a near object zvith large, hard surfaces, against zvhich a small agile fish is 

 practically inaccessible (Abudefduf viarginatus, Elacatinus occanops). The 

 escape of these individuals zvas therefore not due to their conspicuous color- 

 ation, but zvas rather in spite of it. 



IX. THE RAPIDITY AND NICETY OF THE ADJUSTMENT OF THE 

 GRAY SNAPPER TO ITS FOOD. 



In this section there are brought together a few instances of behavior 

 adjustment which appear to bear on the theory of warning coloration. 



On July 14, 1905, there were fed to the laboratory colony of gray snap- 

 pers 151 atherinas, the last 28 of which were blue. Immediately afterward 

 there were offered 3 blue atherina-shaped pieces of the arms of the medusa 

 Cassiopea xamachana. These pieces induced no reaction whatever in the 

 snappers, although they greatly resembled a blue atherina which was thrown 

 immediately before them and at once taken. When it was clear that the fish 

 would not take the blue cassiopea pieces, they were offered a composite of 



' I am indebted for this specimen to Mr. Davenport 'Hooker. 



