310 Papers from the Marine Biological Laboratory at Tortugas. 



conspicuoiisness, be quickly exterminated, it may be objected that their 

 colors are in fact warning colors, that the reefs with their nettling corals 

 furnish the disagreeable qualities which protect the fish and which corre- 

 spond to the unpleasant attributes of warningly-colored insects. It may be 

 urged that, just as insectivorous foes, after attacking warningly-colored 

 insects and experiencing their unpleasant qualities, afterward let them 

 alone, so piscivorous fish, after being bumped or stung in their efforts to 

 capture coral-reef fish, subsequently refrain from such efforts. Coral-reef 

 fish, removed from the reefs, are stripped of their disagreeable attributes 

 and are at once attacked. In like manner warningly-colored insects, if de- 

 prived of their unpleasant attributes, would doubtless be soon attacked 

 and exterminated. Thus, it may be said, the two cases are quite parallel 

 and the conspicuousness of the coral-reef fish is as much an instance of 

 warning coloration as that of warningly-colored insects, with the difference 

 that the association formed by their enemies is in the case of insects with 

 an unpleasant attribute inherent in the insect, and in the case of coral-reef 

 fish with a similar attribute belonging to their environment. There is a meas- 

 ure of truth in this contention, for no doubt the sight of the reefs " warns " 

 predaceous fish of the futility of pursuing prey into them, and no doubt 

 also the coloration of certain insects may " warn " their foes of their unpala- 

 tability. That the coloration of unpalatable insects is unnecessary as a warn- 

 ing and that it has therefore not developed under the action of selection are 

 propositions which are discussed elsewhere in this paper. The evidence that 

 the conspicuousness of coral-reef fish does not warn the gray snapper has been 

 already presented, so that it need be here only added that in any pursuit by 

 enemies, whether outside the reefs or within them, the conspicuousness of 

 these fish is a disadvantage to them. Their capture by the gray snapper can 

 serve only to strengthen in him a mode of behavior which would be corre- 

 lated in human consciousness with the proposition " that gaudy morsel is 

 good to eat." A gaudiness which serves to advertise palatability is surely 

 in this case disadvantageous. It could not, therefore, have developed through 

 selection, which, had it acted on these fishes with sufficient intensity, should 

 rather have brought about protective coloration. That this result has not 

 been reached may be due in part to the lack of intensity in the selective 

 process, since selection is held in abeyance by the reefs, but more probably 

 results from the inability of the fishes to vary in the necessary direction. 



If the conspicuousness of the coral-reef fish is not necessary in its court- 

 ship, and does not serve to warn enemies of unpleasant attributes, and does 

 not aid its possessor in eluding enemies or approaching prey, it can, so far 

 as I can see, and whatever be the physiological uses of the chemical sub- 

 stances involved, have no biological meaning. It has arisen not through selec- 

 tion of any sort, but because the conditions of life permit a suspension of 



