Aposematic Sounds 



no birds. When these came into being and 

 began to prey upon insects, the conspicuously 

 coloured species which were not inedible or 

 very unpalatable would soon become extinct, 

 while those that were inedible would survive as 

 warningly-coloured insects. In other cases it is 

 not improbable that these warningly-coloured 

 creatures have arisen by mutations from more 

 soberly - hued insects. It is conceivable that 

 every now and again a mutation occurs which 

 renders its possessor conspicuous. This will 

 result in the early destruction of these aberrant 

 individuals unless their newly-acquired gaudi- 

 ness is either correlated with, or the result of, 

 distastefulness. 



In the case of warning colouration, the Neo- 

 Darwinians have, as usual, pursued their theory 

 to absurd lengths. Professor Poulton, for 

 example, extends it to sounds and attitudes. 

 "Sound," he writes, on page 324 of Essays on 

 Evolution, " may be employed as an Aposematic 

 character, as in the hiss of some snakes and some 

 lizards. Certain poisonous snakes when dis- 

 turbed produce by an entirely different method 

 a far-reaching sound not unlike the hiss. 

 Thus the rattle-snake (Crotalus) of America 

 rapidly vibrates the series of dry, horny, cuticular 

 cells, movably articulated to each other and to 

 the end of the tail. The stage through which 

 the character probably arose is witnessed in 



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